LTC4065/LTC4065A Standalone 750mA Li-Ion Battery Charger in 2 (cid:215) 2 DFN FEATURES DESCRIPTIOU ■ Complete Linear Charger in 2mm (cid:215)(cid:215)(cid:215)(cid:215)(cid:215) 2mm DFN The LTC®4065 is a complete constant-current/constant- Package voltage linear charger for single-cell lithium-ion batteries. ■ C/10 Charge Current Detection Output Its 2mm (cid:215) 2mm DFN package and low external component ■ Timer Termination count make the LTC4065 especially well-suited for por- ■ Charge Current Programmable up to 750mA with table applications. Furthermore, LTC4065 is specifically 5% Accuracy designed to work within USB power specifications. ■ No External MOSFET, Sense Resistor or Blocking The CHRG pin indicates when charge current has dropped Diode Required to ten percent of its programmed value (C/10). An internal ■ Preset 4.2V Float Voltage with 0.6% Accuracy timer terminates charging according to battery manufac- ■ Constant-Current/Constant-Voltage Operation with turer specifications. Thermal Feedback to Maximize Charging Rate Without Risk of Overheating No external sense resistor or blocking diode is required ■ ACPR Pin Indicates Presence of Input Supply due to the internal MOSFET architecture. Thermal feed- (LTC4065A Only) back regulates charge current to limit the die temperature ■ Charge Current Monitor Output for Gas Gauging during high power operation or high ambient temperature ■ Automatic Recharge conditions. ■ Charges Single Cell Li-Ion Batteries Directly from When the input supply (wall adapter or USB supply) is USB Port removed, the LTC4065 automatically enters a low current ■ 20(cid:181)A Supply Current in Shutdown Mode state, dropping battery drain current to less than 1(cid:181)A. With ■ Soft-Start Limits Inrush Current power applied, LTC4065 can be put into shutdown mode, ■ Tiny 6-Lead (2mm (cid:215) 2mm) DFN Package reducing the supply current to less than 20(cid:181)A. APPLICATIOU S The full-featured LTC4065 also includes automatic re- charge, low-battery charge conditioning (trickle charg- ■ Wireless PDAs ing), soft-start (to limit inrush current) and an open-drain ■ Cellular Phones status pin to indicate the presence of an adequate input ■ Portable Electronics voltage (LTC4065A only). , LT, LTC and LTM are registered trademarks of Linear Technology Corporation. All other trademarks are the property of their respective owners. The LTC4065 is available in a tiny 6-lead, low profile (0.75mm) 2mm (cid:215) 2mm DFN package. TYPICAL APPLICATIOU Standalone Li-Ion Battery Charger 500mA 4.3V TO 5V.5IVN VCC BAT R1 LTC4065 510Ω C1 CHRGPROG + 4.2V 1(cid:181)F Li-Ion R2* EN GND R3 BATTERY 1Ω 2k 4065 TA01 *SERIES 1Ω RESISTOR ONLY NEEDED FOR INDUCTIVE INPUT SUPPLIES 4065fb 1

LTC4065/LTC4065A ABSOLUTE W AXIW UW RATIU GS PACKAGE/ORDER IU FORW ATIOU (Note 1) VCC TOP VIEW t < 1ms and Duty Cycle < 1%................. –0.3V to 7V Steady State ........................................... –0.3V to 6V GND 1 6 PROG BAT, CHRG................................................. –0.3V to 6V CHRG 2 7 5 EN/ACPR* EN (LTC4065), ACPR (LTC4065A)..–0.3V to VCC + 0.3V BAT 3 4 VCC PROG..............................................–0.3V to V + 0.3V CC DC PACKAGE BAT Short-Circuit Duration...........................Continuous 6-LEAD (2mm (cid:215) 2mm) PLASTIC DFN BAT Pin Current................................................. 800mA TJMAX = 125(cid:176)C, θJA = 60(cid:176)C/W (NOTE 3) EXPOSED PAD (PIN 7) IS GND, MUST BE SOLDERED TO PCB PROG Pin Current............................................... 800(cid:181)A *EN PIN 5 ON LTC4065EDC, ACPR PIN 5 ON LTC4065AEDC Junction Temperature (Note 6)............................ 125(cid:176)C ORDER PART NUMBER DC PART MARKING Operating Temperature Range (Note 2).. –40(cid:176)C to 85(cid:176)C LTC4065EDC LBPG Storage Temperature Range................ –65(cid:176)C to 125(cid:176)C LTC4065AEDC LBVJ Order Options Tape and Reel: Add #TR Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: http://www.linear.com/leadfree/ Consult LTC Marketing for parts specified with wider operating temperature ranges. ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25(cid:176)C. V = 5V, V = 3.8V, V = 0V (LTC4065 only) unless otherwise specified. (Note 2) CC BAT EN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V V Supply Voltage (Note 4) ● 3.75 5.5 V CC CC ICC Quiescent VCC Supply Current VBAT = 4.5V (Forces IBAT and IPROG = 0) ● 120 250 (cid:181)A ICCMS VCC Supply Current in Shutdown VEN = 5V (LTC4065) or Float PROG (LTC4065A) ● 20 40 (cid:181)A ICCUV VCC Supply Current in Undervoltage VCC < VBAT, VCC = 3.5V, VBAT = 4V ● 6 11 (cid:181)A Lockout V V Regulated Output Voltage I = 2mA 4.175 4.2 4.225 V FLOAT BAT BAT IBAT = 2mA, 0(cid:176)C < TA < 85(cid:176)C 4.158 4.2 4.242 V I BAT Pin Current R = 10k (0.1%), Current Mode ● 88 100 112 mA BAT PROG R = 2k (0.1%), Current Mode ● 475 500 525 mA PROG IBMS Battery Drain Current in Shutdown VEN = VCC (LTC4065), ● –1 0 1 (cid:181)A Mode V > V (LTC4065A) PROG MS,PROG IBUV Battery Drain Current in Undervoltage VCC = 3.5V, VBAT = 4V ● 0 1 4 (cid:181)A Lockout V V Undervoltage Lockout Voltage V Rising ● 3.4 3.6 3.8 V UVLO CC CC V Falling ● 2.8 3.0 3.2 V CC VPROG PROG Pin Voltage RPROG = 2k, IPROG = 500(cid:181)A ● 0.98 1 1.02 V RPROG = 10k, IPROG = 100(cid:181)A ● 0.98 1 1.02 V V Automatic Shutdown Threshold (V – V ), V Low to High 60 82 100 mV ASD CC BAT CC Voltage (V – V ), V High to Low 15 32 45 mV CC BAT CC V Manual Shutdown High Voltage V Rising 1 V MSH EN (LTC4065) V Manual Shutdown Low Voltage V Falling 0.6 V MSL EN (LTC4065) REN EN Pin Input Resistance ● 0.95 1.5 3.3 MΩ 4065fb 2

LTC4065/LTC4065A ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25(cid:176)C. V = 5V, V = 3.8V, V = 0V (LTC4065 only) unless otherwise specified. (Note 2) CC BAT EN SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS IPROG PROG Pin Pull-Up Current VPROG > 1V 3 (cid:181)A (LTC4065A) V PROG Shutdown Threshold Voltage V Rising ● 3.7 4 4.3 V MS,PROG PROG (LTC4065A Only) tSS Soft-Start Time 180 (cid:181)s I Trickle Charge Current V = 2V, R = 2k (0.1%) 35 50 65 mA TRKL BAT PROG V Trickle Charge Threshold Voltage V Rising ● 2.7 2.9 3.05 V TRKL BAT V Trickle Charge Hysteresis Voltage 90 mV TRHYS ∆VRECHRG Recharge Battery Threshold Voltage VFLOAT – VRECHRG, 0(cid:176)C < TA < 85(cid:176)C 70 100 130 mV ∆VUVCL1 (VCC – VBAT) Undervoltage Current IBAT = 90% Programmed Charge Current 180 220 330 mV ∆VUVCL2 Limit IBAT = 10% Programmed Charge Current 90 125 150 mV t Termination Timer ● 3 4.5 6 Hrs TIMER Recharge Time ● 1.5 2.25 3 Hrs Low-Battery Trickle Charge Time V = 2.5V ● 0.75 1.125 1.5 Hrs BAT V ACPR Pin Output Low Voltage I = 5mA ● 60 105 mV ACPR ACPR (LTC4065A) IACPR ACPR Pin Input Current (LTC4065A) VCC = 4V, VACPR = 4V, VBAT = 4.5V ● 0 1 (cid:181)A V CHRG Pin Output Low Voltage I = 5mA ● 60 105 mV CHRG CHRG ICHRG CHRG Pin Input Current VBAT = 4.5V, VCHRG = 5V ● 0 1 (cid:181)A I End of Charge Indication Current R = 2k (Note 5) ● 0.085 0.1 0.115 mA/mA C/10 PROG Level TLIM Junction Temperature in Constant 115 (cid:176)C Temperature Mode RON Power FET “ON” Resistance IBAT = 200mA 450 mΩ (Between V and BAT) CC f Defective Battery Detection CHRG 2 Hz BADBAT Pulse Frequency D Defective Battery Detection CHRG 75 % BADBAT Pulse Frequency Duty Ratio Note 1: Stresses beyond those listed under Absolute Maximum Ratings Note 4: Although the LTC4065 functions properly at 3.75V, full charge may cause permanent damage to the device. Exposure to any Absolute current requires an input voltage greater than the desired final battery Maximum Rating condition for extended periods may affect device voltage per the ∆VUVCL1 specification. reliability and lifetime. Note 5: I is expressed as a fraction of measured full charge current C/10 Note 2: The LTC4065/LTC4065A are guaranteed to meet performance with indicated PROG resistor. specifications from 0(cid:176)C to 70(cid:176)C. Specifications over the –40(cid:176)C to 85(cid:176)C Note 6: This IC includes overtemperature protection that is intended to operating temperature range are assured by design, characterization and protect the device during momentary overload conditions. Junction correlation with statistical process controls. temperature will exceed 125(cid:176)C when overtemperature protection is active. Note 3: Failure to solder the exposed backside of the package to the PC Continuous operation above the specified maximum operating junction board ground plane will result in a thermal resistance much higher than temperature may impair device reliability. rated. 4065fb 3

LTC4065/LTC4065A TYPICAL PERFORW AU CE CHARACTERISTICS Battery Regulation (Float) Voltage Battery Regulation (Float) Voltage Regulated Output (Float) Voltage vs Battery Charge Current vs Temperature vs Supply Voltage 4.24 4.24 4.24 VCC = 5V TA = 25(cid:176)C 4.23 TA = 25(cid:176)C 4.23 4.23 IBAT = 2mA RPROG = 2k RPROG = 2k 4.22 4.22 4.22 4.21 4.21 4.21 V) V) V) (OAT4.20 (OAT4.20 (OAT4.20 VFL4.19 VFL4.19 VFL4.19 4.18 4.18 4.18 4.17 4.17 4.17 4.16 4.16 4.16 0 100 200 300 400 500 –50 –25 0 25 50 75 100 4 4.5 5 5.5 6 IBAT (mA) TEMPERATURE ((cid:176)C) SUPPLY VOLTAGE (V) 4065 G01 4065 G02 4065 G03 Charge Current vs Temperature Charge Current vs Supply Voltage with Thermal Regulation (Constant Current Mode) Charge Current vs Battery Voltage (Constant Current Mode) 200 600 600 RPROG = 10k VCC = 5V 175 VBAT = 3.8V TA = 25(cid:176)C TA = 25(cid:176)C 500 RPROG = 2k 500 150 400 400 125 THERMAL CONTROL mA) mA) mA) LOOP IN OPERATION (AT100 (AT300 (AT300 B B B I 75 I I 200 200 50 100 100 VCC = 5V 25 VBAT = 3.8V RPROG = 2k 0 0 0 4 4.5 5 5.5 6 0 1 2 3 4 5 –50 0 50 100 150 SUPPLY VOLTAGE (V) VBAT (V) TEMPERATURE ((cid:176)C) 4065 G04 4065 G05 4065 G06 PROG Pin Voltage vs Temperature PROG Pin Voltage Power FET On Resistance (Constant Current Mode) vs Charge Current vs Temperature 1.02 1.2 550 VCC = 5V VCC = 5V VCC = 4V VBAT = 3.8V TA = 25(cid:176)C IBAT = 400mA RPROG = 10k 1.0 RPROG = 2k 500 1.01 0.8 V) V) )Ω450 V (PROG1.00 V (PROG 0.6 R (mDS400 0.4 0.99 0.2 350 0.98 0 300 –50 –25 0 25 50 75 100 0 100 200 300 400 500 –50 –25 0 25 50 75 100 TEMPERATURE ((cid:176)C) IBAT (mA) TEMPERATURE ((cid:176)C) 4065 G07 4065 G08 4065 G09 4065fb 4

LTC4065/LTC4065A TYPICAL PERFORW AU CE CHARACTERISTICS Undervoltage Lockout Threshold Manual Shutdown Threshold Manual Shutdown Supply Current Voltage vs Temperature Voltage vs Temperature (LTC4065) vs Temperature 4.0 1.0 40 VCC = 5V VEN = 5V 3.8 0.9 RISE 30 3.5 RISE (V)CC 3.3 (V)MS0.8 FALL (A)(cid:181)MS 20 V V 0.7 CC FALL I 3.0 10 0.6 2.8 2.5 0.5 0 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE ((cid:176)C) TEMPERATURE ((cid:176)C) TEMPERATURE ((cid:176)C) 4065 G16 4065 G11 4065 G12 Trickle Charge Current Trickle Charge Current EN Pin Current (LTC4065) vs Supply Voltage vs Temperature 4.0 60 60 VCC = 5V VBAT = 2V VCC = 5V 3.5 TA = 25(cid:176)C TA = 25(cid:176)C VBAT = 2V 50 50 3.0 RPROG = 2k RPROG = 2k 40 40 2.5 I (A)(cid:181)EN 21..05 I (mA)BAT 30 I (mA)BAT 30 20 20 1.0 RPROG = 10k RPROG = 10k 10 10 0.5 0 0 0 2 2.5 3 3.5 4 4.5 5 4 4.5 5 5.5 6 –50 –25 0 25 50 75 100 VEN (V) SUPPLY VOLTAGE (V) TEMPERATURE ((cid:176)C) 4065 G13 4065 G14 4065 G15 CHRG Pin Output Low Voltage ACPR Pin Output Low Voltage vs vs Temperature Temperature (LTC4065A Only) 140 140 VCC = 5V VCC = 5V 120 ICHRG = 5mA 120 IACPR = 5mA 100 100 mV) 80 mV) 80 V (CHRG 60 V (ACPR 60 40 40 20 20 0 0 –50 –25 0 25 50 75 100 –50 –25 0 25 50 75 100 TEMPERATURE ((cid:176)C) TEMPERATURE ((cid:176)C) 4065 G10 4065 G17 4065fb 5

LTC4065/LTC4065A TYPICAL PERFORW AU CE CHARACTERISTICS Timer Accuracy vs Temperature Timer Accuracy vs Supply Voltage 1 2.0 VCC = 5V TA = 25(cid:176)C 0 1.5 %) –1 %) 1.0 RACY ( –2 RACY ( 0.5 R ACCU ––34 R ACCU–0.50 ME ME TI –5 TI–1.0 –6 –1.5 –7 –2.0 –50 –25 0 25 50 75 100 4 4.5 5 5.5 6 TEMPERATURE ((cid:176)C) SUPPLY VOLTAGE (V) 4065 G18 4065 G19 PROG Pin Shutdown Threshold vs PROG Pin Shutdown Voltage vs Temperature (LTC4065A Only) Supply Voltage (LTC4065A Only) 5.0 5.0 VCC = 5V TA = 25(cid:176)C 4.5 4.5 4.0 (V)MS(PROG) 4.0 (V)MS(PROG) 3.5 VR V 3.0 3.5 2.5 3.0 2.0 –50 –25 0 25 50 75 100 4 4.5 5 5.5 6 TEMPERATURE ((cid:176)C) SUPPLY VOLTAGE (V) 4065 G20 4065 G21 4065fb 6

LTC4065/LTC4065A PIU FUU CTIOU S GND (Pin 1): Ground. ACPR (Pin 5, LTC4065A Only): Open-Drain Power Supply Status Output. When V is greater than the undervoltage CHRG (Pin 2): Open-Drain Charge Status Output. The CC lockout threshold (3.6V) and V + 80mV (if V > 3.6V), charge status indicator pin has three states: pull-down, BAT BAT the ACPR pin will be pulled down to ground; otherwise the pulse at 2Hz and high impedance state. This output can be pin is high impedance. used as a logic interface or as an LED driver. When the battery is being charged, the CHRG pin is pulled low by an PROG (Pin 6): Charge Current Program and Charge Cur- internal N-channel MOSFET. When the charge current rent Monitor Pin. Connecting a 1% resistor, R , to PROG drops to 10% of the full-scale current, the CHRG pin is ground programs the charge current. When charging in forced to a high impedance state. If the battery voltage constant-current mode, this pin servos to 1V. In all modes, remains below 2.9V for one quarter of the charge time, the the voltage on this pin can be used to measure the charge battery is considered defective and the CHRG pin pulses at current using the following formula: a frequency of 2Hz. V PROG BAT (Pin 3): Charge Current Output. Provides charge I = •1000 BAT R current to the battery and regulates the final float voltage PROG to 4.2V. An internal precision resistor divider on this pin Floating the PROG pin sets the charge current to zero sets the float voltage and is disconnected in shutdown mode. (LTC4065) or puts the part in shutdown mode (LTC4065A). V (Pin 4): Positive Input Supply Voltage. This pin In shutdown mode, the LTC4065A has less than 20(cid:181)A CC provides power to the charger. V can range from 3.75V supply current and about 1(cid:181)A battery drain current. CC to 5.5V. This pin should be bypassed with at least a 1(cid:181)F Exposed Pad (Pin 7): Ground. The Exposed Pad must be capacitor. When V is within 32mV of the BAT pin CC soldered to the PCB ground to provide both electrical con- voltage, the LTC4065 enters shutdown mode, dropping tact and rated thermal performance. I to about 1(cid:181)A. BAT EN (Pin 5, LTC4065 Only): Enable Input Pin. Pulling this pin above the manual shutdown threshold (V is typi- MS cally 0.82V) puts the LTC4065 in shutdown mode. In shutdown mode, the LTC4065 has less than 20(cid:181)A supply current and less than 1(cid:181)A battery drain current. Enable is the default state, but the pin should be tied to GND if unused. 4065fb 7

LTC4065/LTC4065A SI W PLIFIED BLOCK DIAGRAW S VCC 4 VCC TDIE + D3 TA + 115(cid:176)C – C2 UVLO M2 M1 (cid:215)1 (cid:215)1000 3.6V – EN 5 + RENB C1 SHUTDOWN D1 D2 0.82V – BAT 3 + – + MA REF 1.2V CA R1 VA PROG 0.1V R3 – + + – + – 1V MP 1.2V C/10 R4 0.1V CHARGE CONTROL R2 CHRG R5 2 ENABLE LOGIC COUNTER 2.9V – LOBAT BAT + SHUTDOWN OSCILLATOR PROG GND 6 1 4056 F01a RPROG Figure 1a. LTC4065 Block Diagram 4065fb 8

LTC4065/LTC4065A SI W PLIFIED BLOCK DIAGRAW S VCC 4 VCC + C2 D3 + TDIE ACPR – 3.6V TA 5 M2 M1 – 115(cid:176)C (cid:215)1 (cid:215)1000 + D1 D2 C3 BAT – VBAT + 80mV 3 + – + MA REF 1.2V CA R1 VA PROG 0.1V R3 – + + – + – 1V C/10 R4 MP 1.2V 0.1V R2 CHARGE CONTROL 2 CHRG R5 ENABLE LOGIC COUNTER 2.9V – + LOBAT SHUTDOWN C1 BAT + 4V – OSCILLATOR PROG GND 6 1 4056 F01b RPROG Figure 1b. LTC4065A Block Diagram OPERATIOU The LTC4065 is a linear battery charger designed primarily low-battery conditioning adhere to battery manufacturer for charging single cell lithium-ion batteries. Featuring an safety guidelines. Furthermore, the LTC4065 is capable of internal P-channel power MOSFET, the charger uses a operating from a USB power source. constant-current/constant-voltage charge algorithm with An internal thermal limit reduces the programmed charge programmable current. Charge current can be programmed current if the die temperature attempts to rise above a up to 750mA with a final float voltage accuracy of –0.6%. preset value of approximately 115(cid:176)C. This feature protects The CHRG open-drain status output indicates if C/10 has the LTC4065 from excessive temperature and allows the been reached. No blocking diode or external sense resistor user to push the limits of the power handling capability of is required; thus, the basic charger circuit requires only two external components. The ACPR pin (LTC4065A) a given circuit board without risk of damaging the LTC4065 monitors the status of the input voltage with an open-drain or external components. Another benefit of the LTC4065 output. An internal termination timer and trickle charge thermal limit is that charge current can be set according to 4065fb 9

LTC4065/LTC4065A OPERATIOU typical, not worst-case, ambient temperatures for a given program resistor and the charge current are calculated application with the assurance that the charger will auto- using the following equations: matically reduce the current in worst-case conditions. 1V 1000V The charge cycle begins when the following conditions are R =1000• ,I = PROG CHG I R met: the voltage at the V pin exceeds 3.6V and approxi- CHG PROG CC mately 80mV above the BAT pin voltage, a program The charge current out of the BAT pin can be determined resistor is present from the PROG pin to ground and the EN at any time by monitoring the PROG pin voltage and using pin (LTC4065 only) is pulled below the shutdown thresh- the following equation: old (typically 0.82V). V If the BAT pin voltage is below 2.9V, the charger goes into I = PROG •1000 BAT trickle charge mode, charging the battery at one-tenth the RPROG programmed charge current to bring the cell voltage up to a safe level for charging. If the BAT pin voltage is above Undervoltage Lockout (UVLO) 4.1V, the charger will not charge the battery as the cell is An internal undervoltage lockout circuit monitors the input near full capacity. Otherwise, the charger goes into the fast voltage and keeps the charger in undervoltage lockout charge constant-current mode. until V rises above 3.6V and approximately 80mV above CC When the BAT pin approaches the final float voltage the BAT pin voltage. The 3.6V UVLO circuit has a built-in (4.2V), the LTC4065 enters constant-voltage mode and hysteresis of approximately 0.6V and the automatic shut- the charge current begins to decrease. When the current down threshold has a built-in hysteresis of approximately drops to 10% of the full-scale charge current, an internal 50mV. During undervoltage lockout conditions, maxi- comparator turns off the N-channel MOSFET on the CHRG mum battery drain current is 4(cid:181)A and maximum supply pin and the pin assumes a high impedance state. current is 11(cid:181)A. An internal timer sets the total charge time, t (typi- TIMER Shutdown Mode cally 4.5 hours). When this time elapses, the charge cycle terminates and the CHRG pin assumes a high impedance The LTC4065 can be disabled by pulling the EN pin above state. To restart the charge cycle, remove the input voltage the shutdown threshold (approximately 0.82V). The and reapply it, momentarily force the EN pin above V LTC4065A can be disabled by floating the PROG pin. In MS (typically 0.82V) for LTC4065, or momentarily float the shutdown mode, the battery drain current is reduced to PROG pin and reconnect it (LTC4065A). The charge cycle less than 1(cid:181)A and the supply current to about 20(cid:181)A. will automatically restart if the BAT pin voltage falls below Timer and Recharge V (typically 4.1V). RECHRG The LTC4065 has an internal termination timer that starts When the input voltage is not present, the battery drain when an input voltage greater than the undervoltage current is reduced to less than 4(cid:181)A. The LTC4065 can also lockout threshold is applied to V , or when leaving be shut down by pulling the EN pin above the shutdown CC threshold voltage. To put LTC4065A in shutdown mode, shutdown the battery voltage is less than the recharge float the PROG pin. This reduces input quiescent current threshold. to less than 20(cid:181)A and battery drain current to less than 1(cid:181)A. At power-up or when exiting shutdown, if the battery voltage is less than the recharge threshold, the charge Programming Charge Current time is set to 4.5 hours. If the battery voltage is greater than The charge current is programmed using a single resistor the recharge threshold at power-up or when exiting shut- from the PROG pin to ground. The battery charge current down, the timer will not start and charging is prevented is 1000 times the current out of the PROG pin. The since the battery is at or near full capacity. 4065fb 10

LTC4065/LTC4065A OPERATIOU Once the charge cycle terminates, the LTC4065 continu- the ACPR pin is high impedance indicating that the ously monitors the BAT pin voltage using a comparator LTC4065A is unable to charge the battery. with a 2ms filter time. When the average battery voltage falls below 4.1V (which corresponds to 80% to 90% Charge Current Soft-Start and Soft-Stop battery capacity), a new charge cycle is initiated and a 2.25 The LTC4065 includes a soft-start circuit to minimize the hour timer begins. This ensures that the battery is kept at, inrush current at the start of a charge cycle. When a charge or near, a fully charged condition and eliminates the need cycle is initiated, the charge current ramps from zero to the for periodic charge cycle initiations. The CHRG output full-scale current over a period of approximately 180(cid:181)s. assumes a strong pull-down state during recharge cycles Likewise, internal circuitry slowly ramps the charge cur- until C/10 is reached when it transitions to a high rent from full-scale to zero when the charger is shut off or impendance state. self terminates. This has the effect of minimizing the transient current load on the power supply during start-up Trickle Charge and Defective Battery Detection and charge termination. At the beginning of a charge cycle, if the battery voltage is low (below 2.9V), the charger goes into trickle charge, Constant-Current/Constant-Voltage/ reducing the charge current to 10% of the full-scale Constant-Temperature current. If the low-battery voltage persists for one quarter The LTC4065/LTC4065A use a unique architecture to of the total time (1.125 hour), the battery is assumed to be charge a battery in a constant-current, constant-voltage defective, the charge cycle is terminated and the CHRG pin and constant-temperature fashion. Figures 1a and 1b output pulses at a frequency of 2Hz with a 75% duty cycle. show simplified block diagrams of the LTC4065 and If for any reason the battery voltage rises above 2.9V, the LTC4065A, respectively. Three of the amplifier feedback charge cycle will be restarted. To restart the charge cycle loops shown control the constant-current, CA, constant- (i.e., when the defective battery is replaced with a dis- voltage, VA, and constant-temperature, TA modes. A charged battery), simply remove the input voltage and fourth amplifier feedback loop, MA, is used to increase the reapply it, temporarily pull the EN pin above the shutdown output impedance of the current source pair; M1 and M2 threshold (LTC4065), or momentarily float the PROG pin (note that M1 is the internal P-channel power MOSFET). It and reconnect it (LTC4065A). ensures that the drain current of M1 is exactly 1000 times CHRG Status Output Pin greater than the drain current of M2. The charge status indicator pin has three states: pull- Amplifiers CA and VA are used in separate feedback loops down, pulse at 2Hz (see Trickle Charge and Defective to force the charger into constant-current or constant- Battery Detection) and high impedance. The pull-down voltage mode, respectively. Diodes D1 and D2 provide state indicates that the LTC4065 is in a charge cycle. A high priority to either the constant-current or constant-voltage impedance state indicates that the charge current has loop; whichever is trying to reduce the charge current the dropped below 10% of the full-scale current or the LTC4065 most. The output of the other amplifier saturates low is disabled. Figure 2 shows the CHRG status under various which effectively removes its loop from the system. When conditions. in constant-current mode, CA servos the voltage at the PROG pin to be precisely 1V. VA servos its inverting input Power Supply Status Indicator to an internal reference voltage when in constant-voltage (ACPR, LTC4065A Only) mode and the internal resistor divider, made up of R1 and R2, ensures that the battery voltage is maintained at 4.2V. The power supply status output has two states: pull-down The PROG pin voltage gives an indication of the charge and high impedance. The pull-down state indicates that V is above the undervoltage lockout threshold (see current during constant-voltage mode as discussed in CC Undervoltage Lockout). When this condition is not met, “Programming Charge Current”. 4065fb 11

LTC4065/LTC4065A OPERATIOU ENABLE UVLO UVLO MODE POWER NO NO ON IS EN > SHUTDOWN IF VCC > 3.6V AND CHRG HIGH IMPEDANCE THRESHOLD? VCC > VBAT + 80mV? YES YES SHUTDOWN MODE CHRG HIGH IMPEDANCE VBAT ≤ 2.9V 2.9V < VBAT < 4.1V VBAT > 4.1V TRICKLE CHARGE MODE FAST CHARGE MODE STANDBY MODE 1/10 FULL CHARGE CURRENT FULL CHARGE CURRENT NO CHARGE CURRENT CHRG STRONG PULL-DOWN CHRG STRONG PULL-DOWN CHRG HIGH IMPEDANCE 1/4 CHARGE CYCLE NO CHARGE CYCLE NO (1.125 HOURS) (4.5 HOURS) DEFECTIVE BATTERY RECHARGE IS VBAT < 2.9V? IS VBAT < 4.1V? YES YES BAD BATTERY MODE RECHARGE MODE NO CHARGE CURRENT FULL CHARGE CURRENT CHRG PULSES (2Hz) CHRG STRONG PULL-DOWN VCC < 3V 1/2 CHARGE CYCLE OR (2.25 HOURS) EN > SHDN THRESHOLD 4065 F02 Figure 2. State Diagram of LTC4065 Operation Transconductance amplifier, TA, limits the die tempera- LTC4065/LTC4065A results in the junction temperature ture to approximately 115(cid:176)C when in constant-tempera- approaching 115(cid:176)C, the amplifier (TA) will begin decreas- ture mode. Diode D3 ensures that TA does not affect the ing the charge current to limit the die temperature to charge current when the die temperature is below approxi- approximately 115(cid:176)C. As the battery voltage rises, the mately 115(cid:176)C. The PROG pin voltage continues to give an LTC4065/LTC4065A either return to constant-current mode indication of the charge current. or enter constant-voltage mode straight from constant- In typical operation, the charge cycle begins in constant- temperature mode. Regardless of mode, the voltage at current mode with the current delivered to the battery the PROG pin is proportional to the current delivered to equal to 1000V/R . If the power dissipation of the the battery. PROG 4065fb 12

LTC4065/LTC4065A APPLICATIOU S IU FORW ATIOU Undervoltage Charge Current Limiting (UVCL) than 600mA. Since the LTC4065 will demand a charge current higher than the current limit of the voltage supply, The LTC4065/LTC4065A includes undervoltage charge the supply voltage will drop to the battery voltage plus (∆V ) current limiting that prevents full charge cur- UVCL1 600mA times the “on” resistance of the internal PFET. The rent until the input supply voltage reaches approximately “on” resistance of the LTC4065 power device is approxi- 200mV above the battery voltage. This feature is particu- mately 450mΩ with a 5V supply. The actual “on” resis- larly useful if the LTC4065 is powered from a supply with tance will be slightly higher due to the fact that the input long leads (or any relatively high output impedance). supply will drop to less than 5V. The power dissipated For example, USB-powered systems tend to have highly during this phase of charging is less than 240mW. That is variable source impedances (due primarily to cable quality a 76% improvement over the non-current limited supply and length). A transient load combined with such imped- power dissipation. ance can easily trip the UVLO threshold and turn the charger off unless undervoltage charge current limiting is USB and Wall Adapter Power implemented. Although the LTC4065/LTC4065A allow charging from a Consider a situation where the LTC4065 is operating USB port, a wall adapter can also be used to charge Li-Ion under normal conditions and the input supply voltage batteries. Figure 3 shows an example of how to combine begins to droop (e.g., an external load drags the input wall adapter and USB power inputs. A P-channel MOSFET, supply down). If the input voltage reachesV + ∆V MP1, is used to prevent back conducting into the USB port BAT UVCL1 (approximately 220mV above the battery voltage), when a wall adapter is present and Schottky diode, D1, is undervoltage charge current limiting will begin to reduce used to prevent USB power loss through the 1k pull-down the charge current in an attempt to maintain ∆V resistor. UVCL1 between the V input and the BAT output of the IC. The CC Typically a wall adapter can supply significantly more LTC4065 will continue to operate at the reduced charge current than the 500mA-limited USB port. Therefore, an current until the input supply voltage is increased or N-channel MOSFET, MN1, and an extra program resistor voltage mode reduces the charge current further. are used to increase the charge current to 750mA when the wall adapter is present. Operation from Current Limited Wall Adapter By using a current limited wall adapter as the input 5V WALL ADAPTER ICHG supply, the LTC4065 dissipates significantly less power 750mA BAT 3 SYSTEM when programmed for a current higher than the limit of ICHG D1 LOAD LTC4065 4 the supply as compared to using a non-current limited USB VCC supply at the same charge current. POWER MP1 PROG 6 + Li-Ion 500mA BATTERY ICHG Consider a situation where an application demands a 4.02k MN1 600mA charge current for an 800mAh Li-Ion battery. If a 2k 1k typical 5V (non-current limited) input supply is available 4065 F03 then the peak power dissipation inside the part can exceed 1W. Figure 3. Combining Wall Adapter and USB Power Now consider the same scenario, but with a 5V input Stability Considerations supply with a 600mA current limit. To take advantage of the supply, it is necessary to program the LTC4065 to The LTC4065/LTC4065A contain two control loops: con- charge at a current above 600mA. Assume that the LTC4065 stant-voltage and constant-current. The constant-voltage is programmed for 650mA (i.e., R = 1.54k) to ensure loop is stable without any compensation when a battery is PROG that part tolerances maintain a programmed current higher connected with low impedance leads. Excessive lead 4065fb 13

LTC4065/LTC4065A APPLICATIOU S IU FORW ATIOU length, however, may add enough series inductance to Power Dissipation require a bypass capacitor of at least 1(cid:181)F from BAT to The conditions that cause the LTC4065/LTC4065A to GND. Furthermore, a 4.7(cid:181)F capacitor with a 0.2Ω to 1Ω reduce charge current through thermal feedback can be series resistor from BAT to GND is required to keep ripple approximated by considering the power dissipated in the voltage low when the battery is disconnected. IC. For high charge currents, the LTC4065/LTC4065A High value capacitors with very low ESR (especially ce- power dissipation is approximately: ramic) may reduce the constant-voltage loop phase mar- P = (V – V ) • I D CC BAT BAT gin. Ceramic capacitors up to 22(cid:181)F may be used in parallel with a battery, but larger ceramics should be decoupled Where PD is the power dissipated, VCC is the input supply with 0.2Ω to 1Ω of series resistance. voltage, VBAT is the battery voltage and IBAT is the charge current. It is not necessary to perform any worst-case In constant-current mode, the PROG pin is in the feedback power dissipation scenarios because the LTC4065 will loop, not the battery. Because of the additional pole automatically reduce the charge current to maintain the created by the PROG pin capacitance, capacitance on this die temperature at approximately 115(cid:176)C. However, the pin must be kept to a minimum. With no additional approximate ambient temperature at which the thermal capacitance on the PROG pin, the charger is stable with feedback begins to protect the IC is: program resistor values as high as 25k. However, addi- tional capacitance on this node reduces the maximum TA = 115(cid:176)C – PD • θJA allowed program resistor. The pole frequency at the PROG T = 115(cid:176)C – (V – V ) • I • θ A CC BAT BAT JA pin should be kept above 100kHz. Therefore, if the PROG Example: Consider an LTC4065/LTC4065A operating from pin is loaded with a capacitance, C , the following PROG a 5V wall adapter providing 750mA to a 3.6V Li-Ion equation should be used to calculate the maximum resis- battery. The ambient temperature above which the tance value for R : PROG LTC4065/LTC4065A will begin to reduce the 750mA charge 1 current is approximately: R ≤ PROG 2π•105 •CPROG TA = 115(cid:176)C – (5V – 3.6V) • (750mA) • 60(cid:176)C/W Average, rather than instantaneous, battery current may TA = 115(cid:176)C – 1.05W • 60(cid:176)C/W = 115(cid:176)C – 63(cid:176)C be of interest to the user. For example, if a switching power T = 52(cid:176)C A supply operating in low current mode is connected in parallel with the battery, the average current being pulled The LTC4065/LTC4065A can be used above 70(cid:176)C, but the charge current will be reduced from 750mA. The approxi- out of the BAT pin is typically of more interest than the mate current at a given ambient temperature can be instantaneous current pulses. In such a case, a simple RC calculated: filter can be used on the PROG pin to measure the average battery current as shown in Figure 4. A 10K resistor has 115(cid:176)C–T been added between the PROG pin and the filter capacitor I = A BAT to ensure stability. (VCC –VBAT)•θJA Using the previous example with an ambient temperature of 73(cid:176)C, the charge current will be reduced to approxi- LTC4065 10k CHARGE mately: CURRENT PROG MONITOR GND RPROG CFILTER CIRCUITRY 115(cid:176)C–73(cid:176)C 42(cid:176)C I = = =500mA BAT 4065 F04 (5V –3.6V)•60(cid:176)C/W 84(cid:176)C/A Figure 4. Isolating Capacitive Load on the PROG Pin and Filtering 4065fb 14

LTC4065/LTC4065A APPLICATIOU S IU FORW ATIOU Furthermore, the voltage at the PROG pin will change backside of the package and the copper board will result proportionally with the charge current as discussed in the in thermal resistances far greater than 60(cid:176)C/W. As an Programming Charge Current section. example, a correctly soldered LTC4065/LTC4065A can deliver over 750mA to a battery from a 5V supply at room It is important to remember that LTC4065/LTC4065A temperature. Without a backside thermal connection, this applications do not need to be designed for worst-case number could drop to less than 500mA. thermal conditions since the IC will automatically reduce power dissipation when the junction temperature reaches V Bypass Capacitor approximately 115(cid:176)C. CC Many types of capacitors can be used for input bypassing; Board Layout Considerations however, caution must be exercised when using multi- layer ceramic capacitors. Because of the self-resonant and In order to deliver maximum charge current under all high Q characteristics of some types of ceramic capaci- conditions, it is critical that the exposed metal pad on the tors, high voltage transients can be generated under some backside of the LTC4065/LTC4065A package is soldered start-up conditions, such as connecting the charger input to the PC board ground. Correctly soldered to a 2500mm2 to a live power source. For more information, refer to double-sided 1 oz. copper board the LTC4065/LTC4065A Application Note 88. has a thermal resistance of approximately 60(cid:176)C/W. Failure to make thermal contact between the Exposed Pad on the PACKAGE DESCRIPTIOU DC Package 6-Lead Plastic DFN (2mm (cid:215) 2mm) (Reference LTC DWG # 05-08-1703) R = 0.115 0.38 – 0.05 TYP 0.56 – 0.05 4 6 0.675 –0.05 (2 SIDES) 2.50 –0.05 1.15 –0.050(.26 1S I–D0E.S0)5 2(.40 0S I–D0E.S1)0 PACKAGE PIN 1 BAR PIN 1 OUTLINE TOP MARK CHAMFER OF (SEE NOTE 6) EXPOSED PAD 3 1 (DC6) DFN 1103 0.25 – 0.05 0.25 – 0.05 0.50 BSC 0.200 REF 0.75 –0.05 0.50 BSC 1.42 –0.05 1.37 –0.05 (2 SIDES) (2 SIDES) RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS 0.00 – 0.05 BOTTOM VIEW—EXPOSED PAD NOTE: 1. DRAWING TO BE MADE A JEDEC PACKAGE OUTLINE M0-229 VARIATION OF (WCCD-2) 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE 4065fb Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 15 However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen- tation that the interconnection of its circuits as described herein will not infringe on existing patent rights.

LTC4065/LTC4065A RELATED PARTS PART NUMBER DESCRIPTION COMMENTS Battery Chargers LTC1734 Lithium-Ion Linear Battery Charger in ThinSOTTM Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed LTC1734L Lithium-Ion Linear Battery Charger in ThinSOT Low Current Version of LTC1734, 50mA ≤ ICHRG ≤ 180mA LTC4002 Switch Mode Lithium-Ion Battery Charger Standalone, 4.7V ≤ VIN ≤ 24V, 500kHz Frequency, 3 Hour Charge Termination LTC4050 Lithium-Ion Linear Battery Charger Controller Features Preset Voltages, C/10 Charger Detection and Programmable Timer, Input Power Good Indication, Thermistor Interface LTC4052 Monolithic Lithium-Ion Battery Pulse Charger No Blocking Diode or External Power FET Required, ≤1.5A Charge Current LTC4053 USB Compatible Monolithic Li-Ion Battery Charger Standalone Charger with Programmable Timer, Up to 1.25A Charge Current LTC4054 Standalone Linear Li-Ion Battery Charger Thermal Regulation Prevents Overheating, C/10 Termination, with Integrated Pass Transistor in ThinSOT C/10 Indicator, Up to 800mA Charge Current LTC4057 Lithium-Ion Linear Battery Charger Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package LTC4058 Standalone 950mA Lithium-Ion Charger in DFN C/10 Charge Termination, Battery Kelvin Sensing, –7% Charge Accuracy LTC4059 900mA Linear Lithium-Ion Battery Charger 2mm (cid:215) 2mm DFN Package, Thermal Regulation, Charge Current Monitor Output LTC4059A 900mA Linear Lithium-Ion Battery Charger 2mm (cid:215) 2mm DFN Package, Thermal Regulation, Charge Current Monitor Output, ACPR Function LTC4061 Standalone Li-Ion Charger with Thermistor Interface 4.2V, –0.35% Float Voltage, Up to 1A Charge Current, 3mm (cid:215) 3mm DFN LTC4061-4.4 Standalone Li-Ion Charger with Thermistor Interface 4.4V (Max), –0.4% Float Voltage, Up to 1A Charge Current, 3mm (cid:215) 3mm DFN LTC4062 Standalone Linear Li-Ion Battery Charger with 4.2V, –0.35% Float Voltage, Up to 1A Charge Current, 3mm (cid:215) 3mm DFN Micropower Comparator LTC4063 Li-Ion Charger with Linear Regulator Up to 1A Charge Current, 100mA, 125mV LDO, 3mm (cid:215) 3mm DFN LTC4411/LTC4412 Low Loss PowerPathTM Controller in ThinSOT Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes Power Management LTC3405/LTC3405A 300mA (IOUT), 1.5MHz, Synchronous Step-Down 95% Efficiency, VIN: 2.7V to 6V, VOUT = 0.8V, IQ = 20(cid:181)A, ISD < 1(cid:181)A, DC/DC Converter ThinSOT Package LTC3406/LTC3406A 600mA (IOUT), 1.5MHz, Synchronous Step-Down 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.6V, IQ = 20(cid:181)A, ISD < 1(cid:181)A, DC/DC Converter ThinSOT Package LTC3411 1.25A (IOUT), 4MHz, Synchronous Step-Down 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 0.8V, IQ = 60(cid:181)A, ISD < 1(cid:181)A, DC/DC Converter MS Package LTC3440 600mA (IOUT), 2MHz, Synchronous Buck-Boost 95% Efficiency, VIN: 2.5V to 5.5V, VOUT = 2.5V, IQ = 25(cid:181)A, ISD < 1(cid:181)A, DC/DC Converter MS Package LTC4413 Dual Ideal Diode in DFN 2-Channel Ideal Diode ORing, Low Forward ON Resistance, Low Regulated Forward Voltage, 2.5V ≤ VIN ≤ 5.5V ThinSOT and PowerPath are trademarks of Linear Technology Corporation. 4065fb 16 Linear Technology Corporation LT 0406 REV B (cid:149) PRINTED IN THE USA 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 ● FAX: (408) 434-0507 ● www.linear.com ' LINEAR TECHNOLOGY CORPORATION 2005