AT24C256C I²C-Compatible (2-Wire) Serial EEPROM 256‑Kbit (32,768 x 8) Features • Low-Voltage and Standard-Voltage Operation: – V = 1.7V to 5.5V CC • Internally Organized as 32,768 x 8 (256K) • Industrial Temperature Range: -40°C to +85°C • I2C-Compatible (2-Wire) Serial Interface: – 100 kHz Standard mode, 1.7V to 5.5V – 400 kHz Fast mode, 1.7V to 5.5V – 1 MHz Fast Mode Plus (FM+), 2.5V to 5.5V • Schmitt Trigger, Filtered Inputs for Noise Suppression • Bidirectional Data Transfer Protocol • Write‑Protect Pin for Full Array Hardware Data Protection • Ultra Low Active Current (3 mA maximum) and Standby Current (6 μA maximum) • 64-Byte Page Write Mode: – Partial page writes allowed • Random and Sequential Read Modes • Self‑Timed Write Cycle within 5 ms Maximum • ESD Protection > 4,000V • High Reliability: – Endurance: 1,000,000 write cycles – Data retention: 100 years • Green Package Options (Lead-free/Halide-free/RoHS compliant) • Die Sale Options: Wafer Form and Bumped Wafers Packages • 8-Lead SOIC, 8-Lead TSSOP, 8-Pad UDFN and 8-Ball VFBGA © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 1

AT24C256C Table of Contents Features..........................................................................................................................1 Packages.........................................................................................................................1 1. Package Types (not to scale)....................................................................................4 2. Pin Descriptions.........................................................................................................5 2.1. Device Address Inputs (A0, A1, A2).............................................................................................5 2.2. Ground.........................................................................................................................................5 2.3. Serial Data (SDA).........................................................................................................................5 2.4. Serial Clock (SCL)........................................................................................................................5 2.5. Write-Protect (WP).......................................................................................................................6 2.6. Device Power Supply...................................................................................................................6 3. Description.................................................................................................................7 3.1. System Configuration Using 2-Wire Serial EEPROMs ................................................................7 3.2. Block Diagram..............................................................................................................................8 4. Electrical Characteristics...........................................................................................9 4.1. Absolute Maximum Ratings..........................................................................................................9 4.2. DC and AC Operating Range.......................................................................................................9 4.3. DC Characteristics.......................................................................................................................9 4.4. AC Characteristics......................................................................................................................10 4.5. Electrical Specifications..............................................................................................................11 5. Device Operation and Communication....................................................................13 5.1. Clock and Data Transition Requirements...................................................................................13 5.2. Start and Stop Conditions..........................................................................................................13 5.3. Acknowledge and No-Acknowledge...........................................................................................14 5.4. Standby Mode............................................................................................................................14 5.5. Software Reset...........................................................................................................................15 6. Memory Organization..............................................................................................16 6.1. Device Addressing.....................................................................................................................16 7. Write Operations......................................................................................................18 7.1. Byte Write...................................................................................................................................18 7.2. Page Write..................................................................................................................................18 7.3. Acknowledge Polling..................................................................................................................19 7.4. Write Cycle Timing.....................................................................................................................19 7.5. Write Protection..........................................................................................................................20 8. Read Operations.....................................................................................................21 8.1. Current Address Read................................................................................................................21 8.2. Random Read............................................................................................................................21 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 2

AT24C256C 8.3. Sequential Read.........................................................................................................................22 9. Device Default Condition from Microchip................................................................23 10.Packaging Information.............................................................................................24 10.1. Package Marking Information.....................................................................................................24 11. Revision History.......................................................................................................34 The Microchip Web Site................................................................................................35 Customer Change Notification Service..........................................................................35 Customer Support.........................................................................................................35 Product Identification System........................................................................................36 Microchip Devices Code Protection Feature.................................................................36 Legal Notice...................................................................................................................37 Trademarks...................................................................................................................37 Quality Management System Certified by DNV.............................................................38 Worldwide Sales and Service........................................................................................39 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 3

AT24C256C Package Types (not to scale) 1. Package Types (not to scale) 8-Pad UDFN (Top View) A0 1 8 V CC A1 2 7 WP A2 3 6 SCL GND 4 5 SDA 8-Lead SOIC/TSSOP 8-Ball VFBGA (Top View) (Top View) A0 1 8 V A0 1 8 V CC CC A1 2 7 WP A1 2 7 WP 3 6 A2 3 6 SCL A2 SCL GND 4 5 SDA GND 4 5 SDA © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 4

AT24C256C Pin Descriptions 2. Pin Descriptions The descriptions of the pins are listed in Table 2-1. Table 2-1. Pin Function Table Name 8‑Lead SOIC 8‑Lead TSSOP 8‑Pad UDFN(1) 8‑Ball VFBGA Function A0(2) 1 1 1 1 Device Address Input A1(2) 2 2 2 2 Device Address Input A2(2) 3 3 3 3 Device Address Input GND 4 4 4 4 Ground SDA 5 5 5 5 Serial Data SCL 6 6 6 6 Serial Clock WP(2) 7 7 7 7 Write-Protect VCC 8 8 8 8 Device Power Supply Note:  1. The exposed pad on this package can be connected to GND or left floating. 2. If the A0, A1, A2 or WP pins are not driven, they are internally pulled down to GND. In order to operate in a wide variety of application environments, the pull‑down mechanism is intentionally designed to be somewhat strong. Once these pins are biased above the CMOS input buffer’s trip point (~0.5 x V ), the pull‑down mechanism disengages. Microchip recommends connecting these CC pins to a known state whenever possible. 2.1 Device Address Inputs (A0, A1, A2) The A0, A1 and A2 pins are device address inputs that are hard-wired (directly to GND or to V ) for CC compatibility with other 2-wire Serial EEPROM devices. When the pins are hard-wired, as many as eight devices may be addressed on a single bus system. A device is selected when a corresponding hardware and software match is true. If these pins are left floating, the A0, A1 and A2 pins will be internally pulled down to GND. However, due to capacitive coupling that may appear in customer applications, Microchip recommends always connecting the address pins to a known state. When using a pull‑up resistor, Microchip recommends using 10 kΩ or less. 2.2 Ground The ground reference for the power supply. GND should be connected to the system ground. 2.3 Serial Data (SDA) The SDA pin is an open‑drain bidirectional input/output pin used to serially transfer data to and from the device. The SDA pin must be pulled high using an external pull‑up resistor (not to exceed 10 kΩ in value) and may be wire-ORed with any number of other open‑drain or open‑collector pins from other devices on the same bus. 2.4 Serial Clock (SCL) The SCL pin is used to provide a clock to the device and to control the flow of data to and from the device. Command and input data present on the SDA pin is always latched in on the rising edge of SCL, © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 5

AT24C256C Pin Descriptions while output data on the SDA pin is clocked out on the falling edge of SCL. The SCL pin must either be forced high when the serial bus is idle or pulled high using an external pull‑up resistor. 2.5 Write-Protect (WP) The write-protect input, when connected to GND, allows normal write operations. When the WP pin is connected directly to V , all write operations to the protected memory are inhibited. CC If the pin is left floating, the WP pin will be internally pulled down to GND. However, due to capacitive coupling that may appear in customer applications, Microchip recommends always connecting the WP pin to a known state. When using a pull‑up resistor, Microchip recommends using 10 kΩ or less. Table 2-2. Write-Protect WP Pin Status Part of the Array Protected At V Full Array CC At GND Normal Write Operations 2.6 Device Power Supply The V pin is used to supply the source voltage to the device. Operations at invalid V voltages may CC CC produce spurious results and should not be attempted. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 6

AT24C256C Description 3. Description The AT24C256C provides 262,144 bits of Serial Electrically Erasable and Programmable Read-Only Memory (EEPROM) organized as 32,768 words of 8 bits each. The device’s cascading feature allows up to eight devices to share a common 2‑wire bus. The device is optimized for use in many industrial and commercial applications where low‑power and low‑voltage operation are essential. The devices are available in space‑saving 8‑lead SOIC, 8‑lead TSSOP, 8‑pad UDFN and 8‑ball VFBGA packages. All packages operate from 1.7V to 5.5V. 3.1 System Configuration Using 2-Wire Serial EEPROMs VCC RPUP(max) = tR(max) 0.8473 x CL VCC RPUP(min) = VCC - VOL(max) IOL SCL SDA WP I2C Bus Master: Microcontroller A0 VCC A0 VCC A0 VCC A1 Slave 0 WP A1 Slave 1 WP A1 Slave 7 WP AT24CXXX AT24CXXX AT24CXXX A2 SDA A2 SDA A2 SDA GND SCL GND SCL GND SCL GND © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 7

AT24C256C Description 3.2 Block Diagram Hardware Power A0 Address Memory On Reset VCC Comparator System Control Generator Module High Voltage Generation Circuit Write A1 Protection WP er d Control o EEPROM Array ec D w o R Address Register and Counter 1 page Column Decoder A2 SCL Data Register Start Stop Data & ACK Detector D Input/Output Control OUT D GND IN SDA © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 8

AT24C256C Electrical Characteristics 4. Electrical Characteristics 4.1 Absolute Maximum Ratings Temperature under bias -55°C to +125°C Storage temperature -65°C to +150°C V 6.25V CC Voltage on any pin with respect to ground -1.0V to +7.0V DC output current 5.0 mA ESD protection >4 kV Note:  Stresses above those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation listings of this specification are not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. 4.2 DC and AC Operating Range Table 4-1. DC and AC Operating Range AT24C256C Operating Temperature (Case) Industrial Temperature Range -40°C to +85°C V Power Supply Low Voltage Grade 1.7V to 5.5V CC 4.3 DC Characteristics Table 4-2. DC Characteristics Parameter Symbol Minimum Typical(1) Maximum Units Test Conditions Supply Voltage VCC1 1.7 — 5.5 V Supply Current ICC1 — 1.0 2.0 mA VCC = 5.0V, Read at 400 kHz Supply Current ICC2 — 2.0 3.0 mA VCC = 5.0V, Write at 400 kHz Standby Current ISB1 — — 1.0 μA VCC = 1.7V, VIN = VCC or GND — — 6.0 μA VCC = 5.0V, VIN = VCC or GND Input Leakage ILI — 0.10 3.0 μA VIN = VCC or GND; VCC = 5.0V Current Output Leakage ILO — 0.05 3.0 μA VOUT = VCC or GND; Current VCC = 5.0V Input Low Level VIL -0.6 — VCC x 0.3 V Note 2 Input High Level VIH VCC x 0.7 — VCC + 0.5 V Note 2 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 9

AT24C256C Electrical Characteristics Parameter Symbol Minimum Typical(1) Maximum Units Test Conditions Output Low Level VOL1 — — 0.2 V VCC = 1.7V, IOL = 0.15 mA Output Low Level VOL2 — — 0.4 V VCC = 3.0V, IOL = 2.1 mA Note:  1. Typical values characterized at T = +25°C unless otherwise noted. A 2. This parameter is characterized but is not 100% tested in production. 4.4 AC Characteristics Table 4-3. AC Characteristics(1) Parameter Symbol 1.7V 2.5V, 5.0V Units Min. Max. Min. Max. Clock Frequency, SCL f — 400 — 1000 kHz SCL Clock Pulse Width Low t 1300 — 500 — ns LOW Clock Pulse Width High t 600 — 400 — ns HIGH Noise Suppression Time(2) t — 100 — 50 ns I Clock Low to Data Out Valid t 50 900 50 450 ns AA Bus Free Time between Stop and t 1300 — 500 — ns BUF Start(2) Start Hold Time t 600 — 250 — ns HD.STA Start Set‑up Time t 600 — 250 — ns SU.STA Data In Hold Time t 0 — 0 — ns HD.DAT Data In Set‑up Time t 100 — 100 — ns SU.DAT Inputs Rise Time(2) t — 300 — 300 ns R Inputs Fall Time(2) t — 300 — 100 ns F Stop Set-up Time t 600 — 250 — ns SU.STO Data Out Hold Time t 50 — 50 — ns DH Write Cycle Time t — 5 — 5 ms WR Note:  1. AC measurement conditions: – C : 100 pF L – R (SDA bus line pull-up resistor to V ): 1.3 kΩ (1000 kHz), 4 kΩ (400 kHz), 10 kΩ PUP CC (100 kHz) – Input pulse voltages: 0.3 V to 0.7 V CC CC – Input rise and fall times: ≤ 50 ns – Input and output timing reference voltages: 0.5 x V CC © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 10

AT24C256C Electrical Characteristics 2. This parameter is ensured by characterization and is not 100% tested. Figure 4-1. Bus Timing t t HIGH t F R t LOW SCL t t t t t SU.STA HD.STA HD.DAT SU.DAT SU.STO SDA In t t AA BUF t DH SDA Out 4.5 Electrical Specifications 4.5.1 Power-up Requirements and Reset Behavior During a power-up sequence, the V supplied to the AT24C256C should monotonically rise from GND to CC the minimum V level, as specified in Table 4-1, with a slew rate no faster than 0.1 V/μs. CC 4.5.1.1 Device Reset To prevent inadvertent write operations or any other spurious events from occurring during a power‑up sequence, the AT24C256C includes a Power-on Reset (POR) circuit. Upon power‑up, the device will not respond to any commands until the V level crosses the internal voltage threshold (V ) that brings the CC POR device out of Reset and into Standby mode. The system designer must ensure the instructions are not sent to the device until the V supply has CC reached a stable value greater than or equal to the minimum V level. Additionally, once the V is CC CC greater than or equal to the minimum V level, the bus master must wait at least t before sending the CC PUP first command to the device. See Table 4-4 for the values associated with these power‑up parameters. Table 4-4. Power-up Conditions(1) Symbol Parameter Min. Max. Units t Time required after V is stable before the device can accept commands 100 － µs PUP CC V Power-on Reset Threshold Voltage — 1.5 V POR t Minimum time at V = 0V between power cycles 500 — ms POFF CC Note:  1. These parameters are characterized but they are not 100% tested in production. If an event occurs in the system where the V level supplied to the AT24C256C drops below the CC maximum V level specified, it is recommended that a full power cycle sequence be performed by first POR driving the V pin to GND, waiting at least the minimum t time and then performing a new power-up CC POFF sequence in compliance with the requirements defined in this section. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 11

AT24C256C Electrical Characteristics 4.5.2 Pin Capacitance Table 4-5. Pin Capacitance(1) Symbol Test Condition Max. Units Conditions C Input/Output Capacitance (SDA) 8 pF V = 0V I/O I/O C Input Capacitance (A0, A1, A2 and SCL) 6 pF V = 0V IN IN Note:  1. This parameter is characterized but is not 100% tested in production. 4.5.3 EEPROM Cell Performance Characteristics Table 4-6. EEPROM Cell Performance Characteristics Operation Test Condition Min. Max. Units Write Endurance(1) T = 25°C, V = 3.3V, 1,000,000 — Write Cycles A CC Page Write mode Data Retention(1) T = 55°C 100 — Years A Note:  1. Performance is determined through characterization and the qualification process. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 12

AT24C256C Device Operation and Communication 5. Device Operation and Communication The AT24C256C operates as a slave device and utilizes a simple I2C-compatible 2-wire digital serial interface to communicate with a host controller, commonly referred to as the bus master. The master initiates and controls all read and write operations to the slave devices on the serial bus, and both the master and the slave devices can transmit and receive data on the bus. The serial interface is comprised of just two signal lines: Serial Clock (SCL) and Serial Data (SDA). The SCL pin is used to receive the clock signal from the master, while the bidirectional SDA pin is used to receive command and data information from the master as well as to send data back to the master. Data is always latched into the AT24C256C on the rising edge of SCL and always output from the device on the falling edge of SCL. Both the SCL and SDA pin incorporate integrated spike suppression filters and Schmitt Triggers to minimize the effects of input spikes and bus noise. All command and data information is transferred with the Most Significant bit (MSb) first. During bus communication, one data bit is transmitted every clock cycle, and after eight bits (one byte) of data have been transferred, the receiving device must respond with either an Acknowledge (ACK) or a No-Acknowledge (NACK) response bit during a ninth clock cycle (ACK/NACK clock cycle) generated by the master. Therefore, nine clock cycles are required for every one byte of data transferred. There are no unused clock cycles during any read or write operation, so there must not be any interruptions or breaks in the data stream during each data byte transfer and ACK or NACK clock cycle. During data transfers, data on the SDA pin must only change while SCL is low, and the data must remain stable while SCL is high. If data on the SDA pin changes while SCL is high, then either a Start or a Stop condition will occur. Start and Stop conditions are used to initiate and end all serial bus communication between the master and the slave devices. The number of data bytes transferred between a Start and a Stop condition is not limited and is determined by the master. In order for the serial bus to be idle, both the SCL and SDA pins must be in the logic-high state at the same time. 5.1 Clock and Data Transition Requirements The SDA pin is an open-drain terminal and therefore must be pulled high with an external pull‑up resistor. SCL is an input pin that can either be driven high or pulled high using an external pull‑up resistor. Data on the SDA pin may change only during SCL low time periods. Data changes during SCL high periods will indicate a Start or Stop condition as defined below. The relationship of the AC timing parameters with respect to SCL and SDA for the AT24C256C are shown in the timing waveform in Figure 4-1. The AC timing characteristics and specifications are outlined in 4.4 AC Characteristics. 5.2 Start and Stop Conditions 5.2.1 Start Condition A Start condition occurs when there is a high-to-low transition on the SDA pin while the SCL pin is at a stable logic ‘1’ state and will bring the device out of Standby mode. The master uses a Start condition to initiate any data transfer sequence; therefore, every command must begin with a Start condition. The device will continuously monitor the SDA and SCL pins for a Start condition but will not respond unless one is detected. Refer to Figure 5-1 for more details. 5.2.2 Stop Condition A Stop condition occurs when there is a low-to-high transition on the SDA pin while the SCL pin is stable in the logic ‘1’ state. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 13

AT24C256C Device Operation and Communication The master can use the Stop condition to end a data transfer sequence with the AT24C256C, which will subsequently return to Standby mode. The master can also utilize a repeated Start condition instead of a Stop condition to end the current data transfer if the master will perform another operation. Refer to Figure 5-1 for more details. 5.3 Acknowledge and No-Acknowledge After every byte of data is received, the receiving device must confirm to the transmitting device that it has successfully received the data byte by responding with what is known as an Acknowledge (ACK). An ACK is accomplished by the transmitting device first releasing the SDA line at the falling edge of the eighth clock cycle followed by the receiving device responding with a logic ‘0’ during the entire high period of the ninth clock cycle. When the AT24C256C is transmitting data to the master, the master can indicate that it is done receiving data and wants to end the operation by sending a logic ‘1’ response to the AT24C256C instead of an ACK response during the ninth clock cycle. This is known as a No-Acknowledge (NACK) and is accomplished by the master sending a logic ‘1’ during the ninth clock cycle, at which point the AT24C256C will release the SDA line so the master can then generate a Stop condition. The transmitting device, which can be the bus master or the Serial EEPROM, must release the SDA line at the falling edge of the eighth clock cycle to allow the receiving device to drive the SDA line to a logic ‘0’ to ACK the previous 8‑bit word. The receiving device must release the SDA line at the end of the ninth clock cycle to allow the transmitter to continue sending new data. A timing diagram has been provided in Figure 5-1 to better illustrate these requirements. Figure 5-1. Start Condition, Data Transitions, Stop Condition and Acknowledge SDA SDA Must Be Must Be Acknowledge Window Stable Stable 1 2 8 9 SCL SDA Acknowledge Stop Start Valid Condition Condition The transmitting device (Master or Slave) The receiver (Master or Slave) SDA SDA must release the SDA line at this point to allow must release the SDA line at Change Change the receiving device (Master or Slave) to drive the this point to allow the transmitter Allowed Allowed SDA line low to ACK the previous 8-bit word. to continue sending new data. 5.4 Standby Mode The AT24C256C features a low‑power Standby mode that is enabled when any one of the following occurs: • A valid power-up sequence is performed (see 4.5.1 Power-up Requirements and Reset Behavior). • A Stop condition is received by the device unless it initiates an internal write cycle (see 7. Write Operations). • At the completion of an internal write cycle (see 7. Write Operations). © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 14

AT24C256C Device Operation and Communication 5.5 Software Reset After an interruption in protocol, power loss or system Reset, any 2‑wire device can be protocol reset by clocking SCL until SDA is released by the EEPROM and goes high. The number of clock cycles until SDA is released by the EEPROM will vary. The software Reset sequence should not take more than nine dummy clock cycles. Once the software Reset sequence is complete, new protocol can be sent to the device by sending a Start condition followed by the protocol. Refer to Figure 5-2 for an illustration. Figure 5-2. Software Reset Dummy Clock Cycles SCL 1 2 3 8 9 SDA Released Device is by EEPROM Software Reset SDA In the event that the device is still non-responsive or remains active on the SDA bus, a power cycle must be used to reset the device (see 4.5.1 Power-up Requirements and Reset Behavior). © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 15

AT24C256C Memory Organization 6. Memory Organization The AT24C256C is internally organized as 512 pages of 64 bytes each. 6.1 Device Addressing Accessing the device requires an 8‑bit device address byte following a Start condition to enable the device for a read or write operation. Since multiple slave devices can reside on the serial bus, each slave device must have its own unique address so the master can access each device independently. The Most Significant four bits of the device address byte is referred to as the device type identifier. The device type identifier ‘1010' (Ah) is required in bits 7 through 4 of the device address byte (see Table 6-1). Following the 4-bit device type identifier are the hardware slave address bits, A0, A1 and A2. These bits can be used to expand the address space by allowing up to eight Serial EEPROM devices on the same bus. These hardware slave address bits must correlate with the voltage level on the corresponding hardwired device address input pins A0, A1 and A2. The A0, A1 and A2 pins use an internal proprietary circuit that automatically biases the pin to a logic ‘0’ state if the pin is allowed to float. In order to operate in a wide variety of application environments, the pull‑down mechanism is intentionally designed to be somewhat strong. Once the pin is biased above the CMOS input buffer's trip point (~0.5 x V ), the CC pull‑down mechanism disengages. Microchip recommends connecting the A0, A1 and A2 pins to a known state whenever possible. The eighth bit (bit 0) of the device address byte is the Read/Write Select bit. A read operation is initiated if this bit is high and a write operation is initiated if this bit is low. Upon the successful comparison of the device address byte, the AT24C256C will return an ACK. If a valid comparison is not made, the device will NACK. Table 6-1. Device Addressing Package Device Type Identifier Hardware Slave Address Bits R/W Select Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 SOIC, TSSOP, UDFN, 1 0 1 0 A2 A1 A0 R/W VFBGA For all operations except the current address read, two 8‑bit word address bytes must be transmitted to the device immediately following the device address byte. The word address bytes consist of the 15‑bit memory array word address, and are used to specify which byte location in the EEPROM to start reading or writing. The first word address byte contains the seven Most Significant bits of the word address (A14 through A8) in bit positions six through zero, as seen in Table 6-2. Bit 7 of the first word address byte is a “don't care” bit as it is outside of the addressable 256‑Kbit range. Upon completion of the first word address byte, the AT24C256C will return an ACK. Table 6-2. First Word Address Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 X A14 A13 A12 A11 A10 A9 A8 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 16

AT24C256C Memory Organization Next, the second word address byte is sent to the device which provides the remaining eight bits of the word address (A7 through A0). Upon completion of the second word address byte, the AT24C256C will return an ACK. See Table 6-3 to review these bit positions. Table 6-3. Second Word Address Byte Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0 A7 A6 A5 A4 A3 A2 A1 A0 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 17

AT24C256C Write Operations 7. Write Operations All write operations for the AT24C256C begin with the master sending a Start condition, followed by a device address byte with the R/W bit set to logic ‘0’, and then by the word address bytes. The data value(s) to be written to the device immediately follow the word address bytes. 7.1 Byte Write The AT24C256C supports the writing of a single 8‑bit byte. Selecting a data word in the AT24C256C requires a 15‑bit word address. Upon receipt of the proper device address and the word address bytes, the EEPROM will send an Acknowledge. The device will then be ready to receive the 8‑bit data word. Following receipt of the 8‑bit data word, the EEPROM will respond with an ACK. The addressing device, such as a bus master, must then terminate the write operation with a Stop condition. At that time, the EEPROM will enter an internally self‑timed write cycle, which will be completed within t , while the data word is being programmed into WR the nonvolatile EEPROM. All inputs are disabled during this write cycle, and the EEPROM will not respond until the write is complete. Figure 7-1. Byte Write 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 SCL Device Address Byte First Word Address Byte SDA 1 0 1 0 A A A 0 0 X A14 A13 A12 A11 A10 A9 A8 0 2 1 0 MSB MSB Start Condition ACK ACK by Master from Slave from Slave 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Second Word Address Byte Data Word A7 A6 A5 A4 A3 A2 A1 A0 0 D7 D6 D5 D4 D3 D2 D1 D0 0 MSB MSB ACK ACK Stop Condition from Slave from Slave by Master 7.2 Page Write A page write operation allows up to 64 bytes to be written in the same write cycle, provided all bytes are in the same row of the memory array (where address bits A14 through A6 are the same). Partial page writes of less than 64 bytes are also allowed. A page write is initiated the same way as a byte write, but the bus master does not send a Stop condition after the first data word is clocked in. Instead, after the EEPROM acknowledges receipt of the first data word, the bus master can transmit up to sixty three additional data words. The EEPROM will respond with an ACK after each data word is received. Once all data to be written has been sent to the device, the bus master must issue a Stop condition (see Figure 7-2) at which time the internally self-timed write cycle will begin. The lower six bits of the word address are internally incremented following the receipt of each data word. The higher order address bits are not incremented and retain the memory page row location. Page write © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 18

AT24C256C Write Operations operations are limited to writing bytes within a single physical page, regardless of the number of bytes actually being written. When the incremented word address reaches the page boundary, the address counter will roll‑over to the beginning of the same page. Nevertheless, creating a roll‑over event should be avoided as previously loaded data in the page could become unintentionally altered. Figure 7-2. Page Write 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 SCL Device Address Byte First Word Address Byte SDA 1 0 1 0 A2 A1 A0 0 0 X A14 A13 A12 A11 A10 A9 A8 0 MSB MSB Start Condition by Master ACK ACK from Slave from Slave 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Second Word Address Byte Data Word (n) Data Word (n+x), max of 64 without rollover A7 A6 A5 A4 A3 A2 A1 A0 0 D7 D6 D5 D4 D3 D2 D1 D0 0 D7 D6 D5 D4 D3 D2 D1 D0 0 MSB MSB MSB Stop Condition ACK ACK ACK by Master from Slave from Slave from Slave 7.3 Acknowledge Polling An Acknowledge Polling routine can be implemented to optimize time‑sensitive applications that would prefer not to wait the fixed maximum write cycle time (t ). This method allows the application to know WR immediately when the Serial EEPROM write cycle has completed, so a subsequent operation can be started. Once the internally self‑timed write cycle has started, an Acknowledge Polling routine can be initiated. This involves repeatedly sending a Start condition followed by a valid device address byte with the R/W bit set at logic ‘0’. The device will not respond with an ACK while the write cycle is ongoing. Once the internal write cycle has completed, the EEPROM will respond with an ACK, allowing a new read or write operation to be immediately initiated. A flowchart has been included below in Figure 7-3 to better illustrate this technique. Figure 7-3. Acknowledge Polling Flowchart Send Send Start Send any Stop condition followed Did Proceed to YES Write condition by a valid the device next Read or protocol to initiate the Device Address ACK? Write operation write cycle byte with R/W = 0 NO 7.4 Write Cycle Timing The length of the self‑timed write cycle (t ) is defined as the amount of time from the Stop condition that WR begins the internal write cycle to the Start condition of the first device address byte, sent to the © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 19

AT24C256C Write Operations AT24C256C that it subsequently responds to with an ACK. Figure 7-4 has been included to show this measurement. During the internally self‑timed write cycle, any attempts to read from or write to the memory array will not be processed. Figure 7-4. Write Cycle Timing SCL 8 9 9 Data Word n SDA D0 ACK ACK First Acknowledge from the device to a valid device address sequence after tWR write cycle is initiated. The minimum tWR can only be determined through Stop Start the use of an ACK Polling routine. Stop Condition Condition Condition 7.5 Write Protection The AT24C256C utilizes a hardware data protection scheme that allows the user to write‑protect the entire memory contents when the WP pin is at V (or a valid V ). No write protection will be set if the CC IH WP pin is at GND or left floating. Table 7-1. AT24C256C Write-Protect Behavior WP Pin Voltage Part of the Array Protected V Full Array CC GND None － Write Protection Not Enabled The status of the WP pin is sampled at the Stop condition for every byte write or page write operation prior to the start of an internally self‑timed write cycle. Changing the WP pin state after the Stop condition has been sent will not alter or interrupt the execution of the write cycle. If an attempt is made to write to the device while the WP pin has been asserted, the device will acknowledge the device address, word address and data bytes, but no write cycle will occur when the Stop condition is issued. The device will immediately be ready to accept a new read or write command. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 20

AT24C256C Read Operations 8. Read Operations Read operations are initiated the same way as write operations with the exception that the Read/Write Select bit in the device address byte must be a logic '1'. There are three read operations: • Current Address Read • Random Address Read • Sequential Read 8.1 Current Address Read The internal data word address counter maintains the last address accessed during the last read or write operation, incremented by one. This address stays valid between operations as long the V is CC maintained to the part. The address roll‑over during a read is from the last byte of the last page to the first byte of the first page of the memory. A current address read operation will output data according to the location of the internal data word address counter. This is initiated with a Start condition, followed by a valid device address byte with the R/W bit set to logic ‘1’. The device will ACK this sequence and the current address data word is serially clocked out on the SDA line. All types of read operations will be terminated if the bus master does not respond with an ACK (it NACKs) during the ninth clock cycle. After the NACK response, the master may send a Stop condition to complete the protocol, or it can send a Start condition to begin the next sequence. Figure 8-1. Current Address Read 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 SCL Device Address Byte Data Word (n) SDA 1 0 1 0 A A A 1 0 D7 D6 D5 D4 D3 D2 D1 D0 1 2 1 0 MSB MSB Start Condition Stop Condition by Master ACK NACK by Master from Slave from Master 8.2 Random Read A random read begins in the same way as a byte write operation does to load in a new data word address. This is known as a “dummy write” sequence; however, the data byte and the Stop condition of the byte write must be omitted to prevent the part from entering an internal write cycle. Once the device address and word address are clocked in and acknowledged by the EEPROM, the bus master must generate another Start condition. The bus master now initiates a current address read by sending a Start condition, followed by a valid device address byte with the R/W bit set to logic ’1’. The EEPROM will ACK the device address and serially clock out the data word on the SDA line. All types of read operations will be terminated if the bus master does not respond with an ACK (it NACKs) during the ninth clock cycle. After the NACK response, the master may send a Stop condition to complete the protocol, or it can send a Start condition to begin the next sequence. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 21

AT24C256C Read Operations Figure 8-2. Random Read 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 SCL Device Address Byte First Word Address Byte Second Word Address Byte SDA 1 0 1 0 A A A 0 0 X A14 A13 A12 A11 A10 A9 A8 0 A7 A6 A5 A4 A3 A2 A1 A0 0 2 1 0 MSB MSB MSB Start Condition ACK ACK ACK by Master from Slave from Slave from Slave Dummy Write 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Device Address Byte Data Word (n) 1 0 1 0 A A A 1 0 D7 D6 D5 D4 D3 D2 D1 D0 1 2 1 0 MSB MSB Start Condition ACK NACK Stop Condition by Master from Slave from Master by Master 8.3 Sequential Read Sequential reads are initiated by either a current address read or a random read. After the bus master receives a data word, it responds with an Acknowledge. As long as the EEPROM receives an ACK, it will continue to increment the word address and serially clock out sequential data words. When the maximum memory address is reached, the data word address will roll-over and the sequential read will continue from the beginning of the memory array. All types of read operations will be terminated if the bus master does not respond with an ACK (it NACKs) during the ninth clock cycle. After the NACK response, the master may send a Stop condition to complete the protocol, or it can send a Start condition to begin the next sequence. Figure 8-3. Sequential Read 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 SCL Device Address Byte Data Word (n) SDA 1 0 1 0 A A A 1 0 D7 D6 D5 D4 D3 D2 D1 D0 0 2 1 0 MSB MSB Start Condition by Master ACK ACK from Slave from Master 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 1 2 3 4 5 6 7 8 9 Data Word (n+1) Data Word (n+2) Data Word (n+x) D7 D6 D5 D4 D3 D2 D1 D0 0 D7 D6 D5 D4 D3 D2 D1 D0 0 D7 D6 D5 D4 D3 D2 D1 D0 1 MSB MSB MSB Stop Condition ACK ACK NACK by Master from Master from Master from Master © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 22

AT24C256C Device Default Condition from Microchip 9. Device Default Condition from Microchip The AT24C256C is delivered with the EEPROM array set to logic ‘1’, resulting in FFh data in all locations. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 23

AT24C256C Packaging Information 10. Packaging Information 10.1 Package Marking Information AT24C256C: Package Marking Information 8-lead SOIC 8-lead TSSOP ATMLHYWW ATHYWW ###% CO ###%CO YYWWNNN YYWWNNN 8-pad UDFN 8-ball VFBGA 2.0 x 3.0 mm Body 2.35 x 3.73 mm Body ### H% ###U WWNNN NNN Note 1: designates pin 1 Note 2: Package drawings are not to scale Catalog Number Truncation AT24C256C Truncation Code ###: 2EC Date Codes Voltages YY = Year Y = Year WW = Work Week of Assembly % = Minimum Voltage 16: 2016 20: 2020 6: 2016 0: 2020 02: Week 2 L: 1.7V min 17: 2017 21: 2021 7: 2017 1: 2021 04: Week 4 18: 2018 22: 2022 8: 2018 2: 2022 ... 19: 2019 23: 2023 9: 2019 3: 2023 52: Week 52 Country of Origin Device Grade Atmel Truncation CO = Country of Origin H or U: Industrial Grade AT: Atmel ATM: Atmel ATML: Atmel Lot Number or Trace Code NNN = Alphanumeric Trace Code (2 Characters for Small Packages) © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 24

R AT24C256C Packaging Information 8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging 2X 0.10 C A–B D A D NOTE 5 N E 2 E1 2 E1 E NOTE 1 1 2 e NX b B 0.25 C A–B D NOTE 5 TOP VIEW 0.10 C C A A2 SEATING PLANE 8X 0.10 C A1 SIDE VIEW h R0.13 h R0.13 H 0.23 L SEE VIEW C (L1) VIEW A–A VIEW C Microchip Technology Drawing No. C04-057-SN Rev D Sheet 1 of 2 © 2017 Microchip Technology Inc. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 25

R AT24C256C Packaging Information 8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm (.150 In.) Body [SOIC] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging Units MILLIMETERS Dimension Limits MIN NOM MAX Number of Pins N 8 Pitch e 1.27 BSC Overall Height A - - 1.75 Molded Package Thickness A2 1.25 - - Standoff § A1 0.10 - 0.25 Overall Width E 6.00 BSC Molded Package Width E1 3.90 BSC Overall Length D 4.90 BSC Chamfer (Optional) h 0.25 - 0.50 Foot Length L 0.40 - 1.27 Footprint L1 1.04 REF Foot Angle 0° - 8° Lead Thickness c 0.17 - 0.25 Lead Width b 0.31 - 0.51 Mold Draft Angle Top 5° - 15° Mold Draft Angle Bottom 5° - 15° Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. § Significant Characteristic 3. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15mm per side. 4. Dimensioning and tolerancing per ASME Y14.5M BSC: Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only. 5. Datums A & B to be determined at Datum H. Microchip Technology Drawing No. C04-057-SN Rev D Sheet 2 of 2 © 2017 Microchip Technology Inc. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 26

R AT24C256C Packaging Information 8-Lead Plastic Small Outline (SN) - Narrow, 3.90 mm Body [SOIC] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging SILK SCREEN C Y1 X1 E RECOMMENDED LAND PATTERN Units MILLIMETERS Dimension Limits MIN NOM MAX Contact Pitch E 1.27 BSC Contact Pad Spacing C 5.40 Contact Pad Width (X8) X1 0.60 Contact Pad Length (X8) Y1 1.55 Notes: 1. Dimensioning and tolerancing per ASME Y14.5M BSC: Basic Dimension. Theoretically exact value shown without tolerances. Microchip Technology Drawing C04-2057-SN Rev B © 2017 Microchip Technology Inc. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 27

M AT24C256C Packaging Diagrams and Parameters Packaging Information 8-Lead Plastic Thin Shrink Small Outline (ST) – 4.4 mm Body [TSSOP] Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging D N E E1 NOTE1 1 2 b e c A A2 φ A1 L1 L Units MILLIMETERS Dimension Limits MIN NOM MAX Number of Pins N 8 Pitch e 0.65 BSC Overall Height A – – 1.20 Molded Package Thickness A2 0.80 1.00 1.05 Standoff A1 0.05 – 0.15 Overall Width E 6.40 BSC Molded Package Width E1 4.30 4.40 4.50 Molded Package Length D 2.90 3.00 3.10 Foot Length L 0.45 0.60 0.75 Footprint L1 1.00 REF Foot Angle φ 0° – 8° Lead Thickness c 0.09 – 0.20 Lead Width b 0.19 – 0.30 Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.15 mm per side. 3. Dimensioning and tolerancing per ASME Y14.5M. BSC:Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only. MicrochipTechnologyDrawingC04-086B ©2007 Microchip Technology Inc. DS00049AR-page 117 © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 28

M AT24C256C Packaging Diagrams and Parameters Packaging Information Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging DS00049BC-page 96 2009 Microchip Technology Inc. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 29

AT24C256C Packaging Information 8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN] Atmel Legacy YNZ Package Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging D A B N (DATUM A) E (DATUM B) NOTE 1 2X 0.10 C 1 2 2X 0.10 C TOP VIEW 0.10 C A1 C A SEATING PLANE 8X (A3) 0.08 C SIDE VIEW 0.10 C A B D2 e 2 1 2 0.10 C A B E2 K N L 8X b e 0.10 C A B 0.05 C BOTTOM VIEW Microchip Technology Drawing C04-21355-Q4B Rev A Sheet 1 of 2 © 2018 Microchip Technology Incorporated © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 30

AT24C256C Packaging Information 8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN] Atmel Legacy YNZ Package Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging Units MILLIMETERS Dimension Limits MIN NOM MAX Number of Terminals N 8 Pitch e 0.50 BSC Overall Height A 0.50 0.55 0.60 Standoff A1 0.00 0.02 0.05 Terminal Thickness A3 0.152 REF Overall Length D 2.00 BSC Exposed Pad Length D2 1.40 1.50 1.60 Overall Width E 3.00 BSC Exposed Pad Width E2 1.20 1.30 1.40 Terminal Width b 0.18 0.25 0.30 Terminal Length L 0.35 0.40 0.45 Terminal-to-Exposed-Pad K 0.20 - - Notes: 1. Pin 1 visual index feature may vary, but must be located within the hatched area. 2. Package is saw singulated 3. Dimensioning and tolerancing per ASME Y14.5M BSC: Basic Dimension. Theoretically exact value shown without tolerances. REF: Reference Dimension, usually without tolerance, for information purposes only. Microchip Technology Drawing C04-21355-Q4B Rev A Sheet 2 of 2 © 2018 Microchip Technology Incorporated © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 31

AT24C256C Packaging Information 8-Lead Ultra Thin Plastic Dual Flat, No Lead Package (Q4B) - 2x3 mm Body [UDFN] Atmel Legacy YNZ Package Note: For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging X2 EV G2 8 ØV C Y2 G1 Y1 1 2 SILK SCREEN X1 E RECOMMENDED LAND PATTERN Units MILLIMETERS Dimension Limits MIN NOM MAX Contact Pitch E 0.50 BSC Optional Center Pad Width X2 1.60 Optional Center Pad Length Y2 1.40 Contact Pad Spacing C 2.90 Contact Pad Width (X8) X1 0.30 Contact Pad Length (X8) Y1 0.85 Contact Pad to Center Pad (X8) G1 0.20 Contact Pad to Contact Pad (X6) G2 0.33 Thermal Via Diameter V 0.30 Thermal Via Pitch EV 1.00 Notes: 1. Dimensioning and tolerancing per ASME Y14.5M BSC: Basic Dimension. Theoretically exact value shown without tolerances. 2. For best soldering results, thermal vias, if used, should be filled or tented to avoid solder loss during reflow process Microchip Technology Drawing C04-21355-Q4B Rev A © 2018 Microchip Technology Incorporated © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 32

AT24C256C Packaging Information f 0.10 C d 0.10 (4X) d 0.08 C A1 BALL D A C A1 BALL PAD CORNER PAD CORNER 2 1 Øb A j n0.15m C A B j n0.08m C B E e C D (e1) A1 B d A2 (d1) A TOP VIEW SIDE VIEW BOTTOM VIEW 8 SOLDER BALLS COMMON DIMENSIONS (Unit of Measure = mm) SYMBOL MIN NOM MAX NOTE A 0.81 0.91 1.00 A1 0.15 0.20 0.25 A2 0.40 0.45 0.50 b 0.25 0.30 0.35 D 2.35 BSC Notes: E 3.73 BSC 1. This drawing is for general e 0.75 BSC 2. Dimension 'b' is measured at the maximum solder ball diameter. e1 0.74 REF 3. Solder ball composition shall be 95.5Sn-4.0Ag-.5Cu. d 0.75 BSC d1 0.80 REF 6/11/13 TITLE GPC DRAWING NO. REV. 8U2-1, 8-ball, 2.35 x 3.73 mm Body, 0.75 mm pitch, Very Thin, Fine-Pitch Ball Grid Array Package GWW 8U2-1 G (VFBGA) Note:  For the most current package drawings, please see the Microchip Packaging Specification located at http://www.microchip.com/packaging. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 33

AT24C256C Revision History 11. Revision History Atmel Document 8568 Revision A (September 2009) Initial document release. Atmel Document 8568 Revision B (March 2010) Part Markings and ordering detail/codes updated. Atmel Document 8568 Revision C (May 2010) Update 8S1 and 8A2 package drawings. Atmel Document 8568 Revision D (September 2011) Atmel global device marking alignment. Update 8S1, 8A2 to 8X, 8MA2, and 8U2-1 package drawings. Atmel Document 8568 Revision E (August 2012) Update template and Atmel logo. Correct 8-lead UDFN to 8-pad UDFN. Update AC characteristics from μs to ns units and their respective values. Update part marking description. Atmel Document 8568 Revision F (January 2015) Add the UDFN Expanded Quantity Option. Update 8X, 8MA2, and 8U2-1 package outline drawings, the ordering information section, and the disclaimer page. Revision A (August 2018) Updated to the Microchip template. Microchip DS20006042 replaces Atmel document 8568. Corrected t typo from 400 ns to 500 ns. Corrected t typo from 550 ns to 450 ns. Updated Part Marking LOW AA Information. Updated the “Software Reset” section. Added ESD rating. Removed lead finish designation. Updated trace code format in package markings. Updated section content throughout for clarification. Added a figure for “System Configuration Using 2-Wire Serial EEPROMs”. Added POR recommendations section. Updated the SOIC, TSSOP and UDFN package drawings to Microchip format. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 34

AT24C256C The Microchip Web Site Microchip provides online support via our web site at http://www.microchip.com/. This web site is used as a means to make files and information easily available to customers. Accessible by using your favorite Internet browser, the web site contains the following information: • Product Support – Data sheets and errata, application notes and sample programs, design resources, user’s guides and hardware support documents, latest software releases and archived software • General Technical Support – Frequently Asked Questions (FAQ), technical support requests, online discussion groups, Microchip consultant program member listing • Business of Microchip – Product selector and ordering guides, latest Microchip press releases, listing of seminars and events, listings of Microchip sales offices, distributors and factory representatives Customer Change Notification Service Microchip’s customer notification service helps keep customers current on Microchip products. Subscribers will receive e-mail notification whenever there are changes, updates, revisions or errata related to a specified product family or development tool of interest. To register, access the Microchip web site at http://www.microchip.com/. Under “Support”, click on “Customer Change Notification” and follow the registration instructions. Customer Support Users of Microchip products can receive assistance through several channels: • Distributor or Representative • Local Sales Office • Field Application Engineer (FAE) • Technical Support Customers should contact their distributor, representative or Field Application Engineer (FAE) for support. Local sales offices are also available to help customers. A listing of sales offices and locations is included in the back of this document. Technical support is available through the web site at: http://www.microchip.com/support © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 35

AT24C256C Product Identification System To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office. AT 2 4 C 2 5 6 C - S S H L - B Shipping Carrier Option B = Bulk (Tubes) T = Tape and Reel, Standard Quantity Option E = Tape and Reel, Extended Quantity Option Product Family 24C = Standard I2C-compatible Operating Voltage Serial EEPROM L = 1.7V to 5.5V Device Grade or Device Density Wafer/Die Thickness 256 = 256 Kilobit H or U = Industrial Temperature Range (-40°C to +85°C) Device Revision 11 = 11mil Wafer Thickness Package Option SS = SOIC X = TSSOP MA = 2.0mm x 3.0mm UDFN C = VFBGA WWU = Wafer Unsawn Examples Device Package Package Package Shipping Carrier Option Device Grade Drawing Option Code AT24C256C‑SSHL‑B SOIC SN SS Bulk (Tubes) Industrial Temperature AT24C256C‑SSHL‑T SOIC SN SS Tape and Reel (-40°C to +85°C) AT24C256C‑XHL‑T TSSOP ST X Tape and Reel AT24C256C‑MAHL‑T UDFN Q4B MA Tape and Reel AT24C256C‑MAHL‑E UDFN Q4B MA Extended Qty. Tape and Reel AT24C256C‑CUL‑T VFBGA 8U2‑1 C Tape and Reel Microchip Devices Code Protection Feature Note the following details of the code protection feature on Microchip devices: • Microchip products meet the specification contained in their particular Microchip Data Sheet. • Microchip believes that its family of products is one of the most secure families of its kind on the market today, when used in the intended manner and under normal conditions. • There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowledge, require using the Microchip products in a manner outside the operating specifications contained in Microchip’s Data Sheets. Most likely, the person doing so is engaged in theft of intellectual property. • Microchip is willing to work with the customer who is concerned about the integrity of their code. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 36

AT24C256C • Neither Microchip nor any other semiconductor manufacturer can guarantee the security of their code. Code protection does not mean that we are guaranteeing the product as “unbreakable.” Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our products. Attempts to break Microchip’s code protection feature may be a violation of the Digital Millennium Copyright Act. If such acts allow unauthorized access to your software or other copyrighted work, you may have a right to sue for relief under that Act. Legal Notice Information contained in this publication regarding device applications and the like is provided only for your convenience and may be superseded by updates. It is your responsibility to ensure that your application meets with your specifications. MICROCHIP MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND WHETHER EXPRESS OR IMPLIED, WRITTEN OR ORAL, STATUTORY OR OTHERWISE, RELATED TO THE INFORMATION, INCLUDING BUT NOT LIMITED TO ITS CONDITION, QUALITY, PERFORMANCE, MERCHANTABILITY OR FITNESS FOR PURPOSE. Microchip disclaims all liability arising from this information and its use. Use of Microchip devices in life support and/or safety applications is entirely at the buyer’s risk, and the buyer agrees to defend, indemnify and hold harmless Microchip from any and all damages, claims, suits, or expenses resulting from such use. No licenses are conveyed, implicitly or otherwise, under any Microchip intellectual property rights unless otherwise stated. Trademarks The Microchip name and logo, the Microchip logo, AnyRate, AVR, AVR logo, AVR Freaks, BitCloud, chipKIT, chipKIT logo, CryptoMemory, CryptoRF, dsPIC, FlashFlex, flexPWR, Heldo, JukeBlox, KeeLoq, Kleer, LANCheck, LINK MD, maXStylus, maXTouch, MediaLB, megaAVR, MOST, MOST logo, MPLAB, OptoLyzer, PIC, picoPower, PICSTART, PIC32 logo, Prochip Designer, QTouch, SAM-BA, SpyNIC, SST, SST Logo, SuperFlash, tinyAVR, UNI/O, and XMEGA are registered trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. ClockWorks, The Embedded Control Solutions Company, EtherSynch, Hyper Speed Control, HyperLight Load, IntelliMOS, mTouch, Precision Edge, and Quiet-Wire are registered trademarks of Microchip Technology Incorporated in the U.S.A. Adjacent Key Suppression, AKS, Analog-for-the-Digital Age, Any Capacitor, AnyIn, AnyOut, BodyCom, CodeGuard, CryptoAuthentication, CryptoAutomotive, CryptoCompanion, CryptoController, dsPICDEM, dsPICDEM.net, Dynamic Average Matching, DAM, ECAN, EtherGREEN, In-Circuit Serial Programming, ICSP, INICnet, Inter-Chip Connectivity, JitterBlocker, KleerNet, KleerNet logo, memBrain, Mindi, MiWi, motorBench, MPASM, MPF, MPLAB Certified logo, MPLIB, MPLINK, MultiTRAK, NetDetach, Omniscient Code Generation, PICDEM, PICDEM.net, PICkit, PICtail, PowerSmart, PureSilicon, QMatrix, REAL ICE, Ripple Blocker, SAM-ICE, Serial Quad I/O, SMART-I.S., SQI, SuperSwitcher, SuperSwitcher II, Total Endurance, TSHARC, USBCheck, VariSense, ViewSpan, WiperLock, Wireless DNA, and ZENA are trademarks of Microchip Technology Incorporated in the U.S.A. and other countries. SQTP is a service mark of Microchip Technology Incorporated in the U.S.A. Silicon Storage Technology is a registered trademark of Microchip Technology Inc. in other countries. GestIC is a registered trademark of Microchip Technology Germany II GmbH & Co. KG, a subsidiary of Microchip Technology Inc., in other countries. All other trademarks mentioned herein are property of their respective companies. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 37

AT24C256C © 2018, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. ISBN: 978-1-5224-3374-3 Quality Management System Certified by DNV ISO/TS 16949 Microchip received ISO/TS-16949:2009 certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona; Gresham, Oregon and design centers in California and India. The Company’s quality system processes and procedures are for its PIC® MCUs and dsPIC® DSCs, KEELOQ® code hopping devices, Serial EEPROMs, microperipherals, nonvolatile memory and analog products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001:2000 certified. © 2018 Microchip Technology Inc. Datasheet DS20006042A-page 38

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Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M icrochip: AT24C256C-MAHL-T AT24C256C-SSHL-B AT24C256C-SSHL-T AT24C256C-XHL-B AT24C256C-XHL-T AT24C256C-MAHL-E