AY0438 32-Segment CMOS LCD Driver FEATURES PIN CONFIGURATION 40-Lead Dual In-line • Drives up to 32 LCD segments of arbitrary config- uration VDD 1 40 CLOCK • CMOS process for: wide supply voltage range, LOAD 2 39 SEG 1 low- power operation, high-noise immunity, wide SEG 32 3 38 SEG 2 temperature range SEG 31 4 37 SEG 3 • CMOS and TTL-compatible inputs SEG 30 5 36 VSS SEG 29 6 35 DATA OUT • Electrostatic discharge protection on all pins SEG 28 7 34 DATA IN • Cascadable SEG 27 8 33 SEG 4 8 • On-chip oscillator SEG 26 9 3 32 SEG 5 SEG 25 10 4 31 LCDF • Requires only three control lines 0 SEG 24 11 30 BP Y SEG 23 12 A 29 SEG 6 APPLICATIONS SEG 22 13 28 SEG 7 SEG 21 14 27 SEG 8 • Industrial displays SEG 20 15 26 SEG 9 • Consumer product displays SEG 19 16 25 SEG 10 SEG 18 17 24 SEG 11 • Telecom product displays SEG 17 18 23 SEG 12 • Automotive dashboard displays SEG 16 19 22 SEG 13 SEG 15 20 21 SEG 14 DESCRIPTION The AY0438 is a CMOS integrated device that drives a liquid crystal display, usually under microprocessor control. The part acts as a smart peripheral that drives up to 32 LCD segments. It needs only three control lines due to its serial input construction. It latches the 44 PLCC data to be displayed and relieves the microprocessor from the task of generating the required waveforms. 012 K The AY0438 can drive any standard or custom parallel CEG 3EG 3EG 3OADDDLOCEG 1EG 2EG 3SS drive LCD display, whether it be field effect or dynamic NSSSLVCSSSV scattering; 7-, 9-, 14- or 16-segment characters; deci- mals; leading + or -; or special symbols. Several AY0438 devices can be cascaded. The AC frequency 6543214443424140 SEG 29 7 39 NC of the LCD waveforms can either be supplied by the SEG 28 8 38 DATA OUT user or generated by attaching a capacitor to the LCD SEG 27 9 37 DATA IN SEG 26 10 36 SEG 4 input, which controls the frequency of an internal oscil- SEG 25 11 35 SEG 5 lator. SEG 24 12 AY0438 34 LCDF SEG 23 13 33 BP The AY0438 is available in 40-lead dual in-line plastic SEG 22 14 32 SEG 6 and 44-lead PLCC packages. Unpackaged dice are SEG 21 15 31 SEG 7 SEG 20 16 30 SEG 8 also available. SEG 19 17 29 NC 89012345678 11222222222 8765432109C G 1G 1G 1G 1G 1G 1G 1G 1G 1EG N EEEEEEEEES SSSSSSSSS (cid:211) 1995 Microchip Technology Inc. DS70010I-page 1

AY0438 FIGURE 1: PIN DESCRIPTIONS Pin # (PDIP Only) Name Direction Description 1 VDD - Supply voltage 2 Load Input Latch data from registers 3-29, 32, 33, 37-39 Seg 1-32 Output Direct drive outputs 30 BP Output Backplane drive output 31 LCDF Input Backplane drive input 34 Data In Input Data input to shift register 35 Data Out Output Data output from shift register 36 VSS Ground Ground 40 Clock Input System clock input FIGURE 2: BLOCK DIAGRAM FIGURE 3: BACKPLANE AND SEGMENT OUTPUT Data in 32-bit Static Shift Register Data out Clock SEG On Load 32 Latches 32 Segment Drivers Backplane 32 Outputs LCDF GLeCnDe rAatCor Bouatcpkuptlane SEG Off FIGURE 4: TIMING DIAGRAM 1/f CLOCK 1 31 32 START Data in SEG 32 SEG 2 SEG 1 tDS tDH Data out tPD Load tPW 1.0 OPERATION: enabled or visible, i.e. the output at Segment Output is 180(cid:176) out-of-phase with the Backplane output 1.1 Data In and Clock (Figure 3). The shift register shifts and outputs on the falling edge 1.2 Load of the clock. Every clock falling edge does a logical left shift. As an example, if 32 clock pulses are supplied as A logic 1 at the Load input (Figure 2) causes the paral- in Figure 4, then the data input at the first clock will out- lel load of the data in the shift register into the latches put at SEG 32, and the last data input (# 32) will output that control the segment drivers. If the Load signal is at SEG 1 when a LOAD signal is enabled (Figure 2). It tied high, then the latches become transparent and the is recommended that a complete 32 bit transfer be segment drivers are always connected to the shift reg- done every time the outputs are updated. A logic 1 at isters. the Data In causes the corresponding segment to be DS70010I-page 2 (cid:211) 1995 Microchip Technology Inc.

AY0438 1.3 LCDf FIGURE 5: OSCILLATOR FREQUENCY GRAPH (TYPICAL @ 25(cid:176) C) LCDf can be driven by an external signal or by con- necting a capacitor between LCDf and ground (GND), 140 which will enable the on-chip oscillator required to gen- erate the backplane output voltage. Figure 5 shows the Hz) 120 relationship between capacitance value and output fre- y ( c quency. Leaving the LCDf input unconnected is not en 100 u recommended. When driven by an external clock, the eq backplane output is in phase with the input clock. When e Fr 80 n cascading two AY0438 devices (Figure 6 and a pl Figure 7), the backplane output can be generated ck 60 a using a capacitor to GND on the first AY0438. This B backplane output can then be connected to the LCDf 40 0 20 40 60 80 100 120 input of the second AY0438. The backplane output of CL (pF) the second device is then used to drive the backplane of the LCD module. FIGURE 6: CASCADING TWO AY0438 DEVICES Data Data Data in Clock 32-bit Static Shift Register out in Clock 32-bit Static Shift Register Data out Load 32 Latches Load 32 Latches 32 Segment Drivers 32 Segment Drivers 1 to 32 33 to 64 LCDF LCD AC Outputs LCD AC Outputs Generator Backplane LCDF Generator Backplane output output Clock Load FIGURE 7: CASCADE TIMING DIAGRAM 1/f CLOCK 1 63 64 START Data in SEG 64 SEG 2 SEG 1 tDS tDH Data out tPD Load tPW (cid:211) 1995 Microchip Technology Inc. DS70010I-page 3

AY0438 1.4 General 1.5 Interfacing to a LCD Module and PIC16CXX Device In order to avoid any race conditions, the Data In and Load signals should not be changed during a falling Figure 8 shows a typical layout of an AY0438 con- edge of the Clock. Figure 4 and Figure 7 show a typical nected to a LCD module and interfaced to a PIC16CXX timing diagram for a 32 segment and 64 segment LCD family device. Example 1 lists code used to program module. the PIC16CXX device. This code was complied using MPASM. FIGURE 8: INTERFACING TO A LCD MODULE AND PIC16CXX DEVICE AY0438 SEG A SEG1 SEG F A LCD SEG7 SEG G F G B Backplane SEG6 SEG E E C SEG5 D PIC16CXX SEG D SEG4 SEG C SEG3 SEG B RB0 Clock SEG2 7 7 RB1 Data In SEG9-15 7 RB2 Load SEG19-23 SEG25-31 RB7 Backplane LCDF EXAMPLE 1: EXAMPLE CODE ;************************************************************************* ;This program shows an interface between a PIC16CXX device ;and the AY0438 LCD controller to control a 7 Segment ;4 digit LCD module. ;The PIC16CXX interface to the AY0438 Hardware: ; ; PORTB bit 0 --> CLK ; PORTB bit 1 --> DATA IN ; PORTB bit 2 --> LOAD ; ;The LCD module is connected to the AY0438 as follows: ; Most Significant digit --> seg1 to seg7 ; 3rd Significant digit --> seg9 to seg15 ; 2nd Significant digit --> seg17 to seg 23 ; Least Significant digit --> seg25 to seg 31 ; DS70010I-page 4 (cid:211) 1995 Microchip Technology Inc.

AY0438 ;The DP are not connected, but can be connected to seg8, 16, 24 & 32. ;For each digit, the segments are connected as: ; Seg A --> seg(8*n + 1) ; Seg B --> seg(8*n + 2) ; Seg C --> seg(8*n + 3) ; Seg D --> seg(8*n + 4) ; Seg E --> seg(8*n + 5) ; Seg F --> seg(8*n + 6) ; Seg G --> seg(8*n + 7) ;where n = 0, 1, 2 and 3 for MSD, 3rdSD, 2ndSD and LSD respectively. ;The firmware uses the values in registers: ; MSD, THRDSD, SCNDSD and LSD to determine the values to be ;pulsed to the AY0438. ;In this example, a pushbutton connected to PORTB bit 7 ;is checked periodically to see if it has been pressed. If so, ;the LCD values in locations MSD to LSD are updated. ;************************************************************************* list p=16c71,f=inhx8m ; ; MSD equ 0x20 THRDSD equ 0x21 SCNDSD equ 0x22 LSD equ 0x23 count equ 0x24 temp equ 0x25 PORTB equ 0x06 #define CLK PORTB,0 #define DATAIN PORTB,1 #define LOAD PORTB,2 #define UPDATELCD PORTB,7 w equ 0 STATUS equ 0x03 C equ 0 RP0 equ 5 OPTION equ 0x81 RBPU equ 7 PCL equ 0x02 PCLATH equ 0x0A ; ; org 0 goto start org 0x10 ; ;This DecodeValue table must reside in page 0 for this program to work ; DecodeValue addwf PCL retlw B'00111111' ;decode for 0 retlw B'00000110' ;decode for 1 retlw B'01011011' ;decode for 2 retlw B'01001111' ;decode for 3 retlw B'01100110' ;decode for 4 retlw B'01101101' ;decode for 5 (cid:211) 1995 Microchip Technology Inc. DS70010I-page 5

AY0438 retlw B'01111101' ;decode for 6 retlw B'00000111' ;decode for 7 retlw B'01111111' ;decode for 8 retlw B'01101111' ;decode for 9 ; ; start clrf PORTB bsf STATUS,RP0 ;set portb 0,1&2 as outputs movlw B'11111000' ; / movwf PORTB ; / bcf OPTION,RBPU ;enable pull-up for switch bcf STATUS,RP0 wait btfsc UPDATELCD ;see if update switch is low goto wait ;no then wait bcf LOAD ;make sure load is disabled movf LSD,w ;get least significant value clrf PCLATH ;PCH = 0 call DecodeValue ;decode the value call Send8 ;serially output the seg values movf SCNDSD,w ;get 2nd significant digit call DecodeValue ;decode it call Send8 ;serially output it movf THRDSD,w ;get 3rd significant digit call DecodeValue ;decode it call Send8 movf MSD,w ;get Most significant value call DecodeValue ;decode it call Send8 ;serially send it bsf LOAD ;toggle the LOAD line bcf LOAD ;to enable the latches KeyReleased btfss UPDATELCD ;wait for key to be released goto KeyReleased goto wait ;repeat loop. ; ;Send8, sends the 8 bits in the W register Send8 movwf temp ;save in temp movlw .8 ;init count movwf count ;to 8 sendloop bcf DATAIN ;make sure DATAIN is low rrf temp ;rotate value through carry btfsc STATUS,C ;if bit clear then skip bsf DATAIN ;else set data bit bsf CLK ;toggle clock bcf CLK ; / decfsz count ;see if 8 done goto sendloop ;no then do all return ;else return end DS70010I-page 6 (cid:211) 1995 Microchip Technology Inc.

AY0438 2.0 ELECTRICAL CHARACTERISTICS Maximum Ratings* VDD..............................................................................................................................................................-0.3V to +12V Inputs (CLK, Data In, Load).................................................................................................................VCC to VDD +0.3V LCDF Input........................................................................................................................................-0.3V to VDD +0.3V Power Dissipation.................................................................................................................................................250 mW Storage Temperature...............................................................................................................................-65˚C to +125˚C Operating Temperature Industrial..............................................................................................................-40˚C to +85˚C * Exceeding these ratings could cause permanent damage to the device. This is a stress rating only and functional operation of this device at these conditions is not implied. Operating ranges are specified in Standard Conditions. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. Data labeled “typical” is presented for design guidance only and is not guaranteed. TABLE 2: DC CHARACTERISTICS VDD = +5V unless otherwise noted, TA = 40(cid:176) C to +85(cid:176) C Characteristics Sym Min Typ Max Units Conditions Supply Voltage VDD +3.0 — +8.5 V Supply Current IDD — 25 60 m A LCDF OSC < 15 kHz — 13 30 m A LCDF OSC < 100 Hz Input High Level VIH 0.5 VDD — VDD V Input Low Level Clock VIL1 0 — 0.1 VDD V 3.0V £ VDD £ 8.5V Data, VIL2 0 — 0.1 VDD V 3.0V £ VDD £ 8.5V Input Leakage Current Load IL — 0.01 – 10 m A VIN = 0V and +5.0V Input Capacitance CI — — 5.0 pF VDD = +5.0V Segment Output Voltage VOH 0.8 VDD — VDD V IOH = -100 m A VOL 0 — 0.1 VDD V IOL = 100 m A LCDF Input High Level VIN 0.9 VDD — VDD V LCDF Input Low Level VIL 0 — 0.1 VDD V LCDF Input Leakage IL — — 10 m A VIN = 0V and +5.0V VDD = +5.0V TABLE 3: AC CHARACTERISTICS Characteristics Sym Min Typ Max Units Conditions Clock Rate f DC — 1.5 MHz 50% duty cycle Data Set-up Time tDS 150 — — nsec Data change to Clk falling edge Data Hold Time tDH 50 — — nsec Load Pulse Width tPW 175 — — nsec Data Out Prop. Delay tPD — — 500 nsec CL = 55 pF (cid:211) 1995 Microchip Technology Inc. DS70010I-page 7

AY0438 NOTES: DS70010I-page 8 (cid:211) 1995 Microchip Technology Inc.

AY0438 AY0438 Product Identification System To order or to obtain information, e.g., on pricing or delivery, please use the listed part numbers, and refer to the factory or the listed sales offices. PART NO. X /XX Package: P = Plastic DIP L = PLCC S = Die in Waffle Pack Temperature - = 0˚C to +70˚C Range: I = 40˚C to +85˚C Device: 32 Segment LCD Driver Sales and Support Products supported by a preliminary Data Sheet may possibly have an errata sheet describing minor operational differences and recommended workarounds. To determine if an errata sheet exists for a particular device, please contact one of the following: 1. Your local Microchip sales office. 2. The Microchip Corporate Literature Center U.S. FAX: (602) 786-7277 3. The Microchip’s Bulletin Board, via your local CompuServe number (CompuServe membership NOT required). Please specify which device, revision of silicon and Data Sheet (include Literature #) you are using. For latest version information and upgrade kits for Microchip Development Tools, please call 1-800-755-2345 or 1-602-786-7302. DS70010I-page 9 (cid:211) 1995 Microchip Technology Inc.

Note the following details of the code protection feature on PICmicro® MCUs. (cid:127) The PICmicro family meets the specifications contained in the Microchip Data Sheet. (cid:127) Microchip believes that its family of PICmicro microcontrollers is one of the most secure products of its kind on the market today, when used in the intended manner and under normal conditions. (cid:127) There are dishonest and possibly illegal methods used to breach the code protection feature. All of these methods, to our knowl- edge, require using the PICmicro microcontroller in a manner outside the operating specifications contained in the data sheet. The person doing so may be engaged in theft of intellectual property. (cid:127) Microchip is willing to work with the customer who is concerned about the integrity of their code. (cid:127) 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”. (cid:127) Code protection is constantly evolving. We at Microchip are committed to continuously improving the code protection features of our product. If you have any further questions about this matter, please contact the local sales office nearest to you. Information contained in this publication regarding device Trademarks applications and the like is intended through suggestion only and may be superseded by updates. It is your responsibility to The Microchip name and logo, the Microchip logo, FilterLab, ensure that your application meets with your specifications. KEELOQ, microID, MPLAB, PIC, PICmicro, PICMASTER, No representation or warranty is given and no liability is PICSTART, PRO MATE, SEEVAL and The Embedded Control assumed by Microchip Technology Incorporated with respect Solutions Company are registered trademarks of Microchip Tech- to the accuracy or use of such information, or infringement of nology Incorporated in the U.S.A. and other countries. patents or other intellectual property rights arising from such dsPIC, ECONOMONITOR, FanSense, FlexROM, fuzzyLAB, use or otherwise. Use of Microchip’s products as critical com- In-Circuit Serial Programming, ICSP, ICEPIC, microPort, ponents in life support systems is not authorized except with Migratable Memory, MPASM, MPLIB, MPLINK, MPSIM, express written approval by Microchip. No licenses are con- MXDEV, PICC, PICDEM, PICDEM.net, rfPIC, Select Mode veyed, implicitly or otherwise, under any intellectual property and Total Endurance are trademarks of Microchip Technology rights. Incorporated in the U.S.A. Serialized Quick Turn Programming (SQTP) is a service mark of Microchip Technology Incorporated in the U.S.A. All other trademarks mentioned herein are property of their respective companies. © 2002, Microchip Technology Incorporated, Printed in the U.S.A., All Rights Reserved. Printed on recycled paper. Microchip received QS-9000 quality system certification for its worldwide headquarters, design and wafer fabrication facilities in Chandler and Tempe, Arizona in July 1999. The Company’s quality system processes and procedures are QS-9000 compliant for its PICmicro® 8-bit MCUs, KEELOQ® code hopping devices, Serial EEPROMs and microperipheral products. In addition, Microchip’s quality system for the design and manufacture of development systems is ISO 9001 certified.  2002 Microchip Technology Inc.

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Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: M icrochip: AY0438T/L AY0438/L AY0438/P AY0438-I/P AY0438-I/L AY0438T-I/L