LTC4052-4.2 LINER
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LTC4052-4.2 405242f APPLICATIO SU FEATURES DESCRIPTIO U TYPICAL APPLICATIO U Lithium-Ion Battery Pulse Charger with Overcurrent Protection Single Cell 4.2V, 1A, Standalone Li-Ion Battery Charger The LTC 4052 is a complete standalone pulse charger with integrated MOSFET for 1-cell lithium-ion batteries. An external sense resistor provides overcurrent limiting as a safety precaution against a user connecting a wall adapter with the incorrect or no current limit. The internal MOSFET prevents reverse battery current from flowing if the input voltage is shorted to ground, eliminating the need for a blocking diode. As the battery accepts charge and approaches the programmed float voltage, the internal MOSFET begins switching off and on with the duty cycle gradually decreas- ing as the battery approaches a fully charged condition. A programmable timer terminates the charge cycle. The near end-of-charge C/10 condition is indicated at the CHRG pin when the average charge current falls to one- tenth of the wall adapter current. Removing the input voltage puts the LTC4052 into a sleep mode, dropping the battery current drain to less than 1mA. The LTC4052 is available in a tiny 8-pin thermally enhanced MSOP package. n Handheld Computers n Cellular Telephones n Cradle Chargers , LTC and LT are registered trademarks of Linear Technology Corporation. n Very Low Power Dissipation: 350mW at 1A n Complete Standalone Pulse Charger for 1-Cell Lithium-Ion Batteries n Requires No Microcontroller, MOSFET or Blocking Diode n Sense Resistor Limits Maximum Current for Safety n Programmable Charge Termination Timer for Maximum Capacity Charging n –1% Float Voltage Accuracy n Near End-of-Charge (C/10) Detection Output n AC Wall Adapter Present Output n Low Battery Drain when Input Supply Is Removed n Automatic Trickle Charge for Low Battery n Automatic Battery Refresh n Thermal Shutdown Protection n Tiny Thermally Enhanced MSOP Package 10k4.7Ω RSENSE 0.05Ω 1-CELL 4.2V Li-Ion BATTERY CHRG ACPR GATE BAT TIMER CTIMER 0.1µF GND VIN LTC4052 SENSE 1µF 0.047µF 0.022µF VIN = 4.5V TO 10V WITH 1A CURRENT LIMIT CHARGE STATUS
4052 TA01
TIME (HOURS) 0 0.5 BATTERY VOLTAGE (V)CHRG (V) CHARGE CURRENT (A) 4052 • TA01b 4.5 4.0 3.5 3.0 1.0 0.5 CONSTANT CURRENT PULSING CURRENT CHARGE CYCLE ENDS C/10 LTC4052 Charge Profile
LTC4052-4.2 405242f Operating Temperature Range (Note 3) .. – 40°C to 85°C MS8 PART MARKING TJMAX = 125°C, qJA = 35°C/W EXPOSED PAD IS GROUND. (MUST BE SOLDERED TO PCB). ABSOLUTE AXI U RATI GSW WW U PACKAGE/ORDER I FOR ATIOUU W (Note 1) SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS VIN Input Supply Voltage Wall Adapter Open Circuit Voltage l 4.5 10 V IIN Input Quiescent Supply Current Full Charge Mode l 0.7 1.4 mA VBAT Battery Float Voltage 0 °C £ TA £ 85°C 4.158 4.200 4.242 V l 4.137 4.200 4.242 V VRECHRG Recharge Battery Voltage Threshold Battery Voltage Falling 0 °C £ TA £ 85°C 3.990 4.050 4.110 V l 3.969 4.050 4.110 V VMARGIN VBAT – VRECHRG Margin l 75 150 225 mV VIMAX Overcurrent Trip Sense Voltage l 90 105 120 mV ITRICKLE Trickle Charge Current V BAT = 2V l 14 24 34 mA VTRICKLE Trickle Charge Threshold Voltage V BAT Rising l 2.35 2.45 2.55 V RDS(ON) Internal Switch On-Resistance V BAT = 2.6V 0.45 0.7 W VBAT = 4V 0.35 0.5 W VGATE GATE Pin Voltage V BAT = 2.6V 6.5 V VBAT = 4V 10.5 V TTIMER TIMER Period Accuracy C TIMER = 0.1mF, Full Charge Mode –10 % ILEAK Battery Leakage Current Through Charger V BAT = 4V, VIN = 0V l 1 mA VSLEEP Sleep Threshold Voltage (V IN – VBAT) Low to High 20 45 70 mV (VIN – VBAT) High to Low 0 15 mV VACPR ACPR Pin Output Low Voltage I ACPR = 3mA l 0.5 0.8 V ILEAKACPR ACPR Pin Leakage Current V IN = 0, VACPR = 6V l 1 mA VCHRG CHRG Pin Output Low Voltage I CHRG = 3mA, Charging, C/10 Not Reached l 0.5 0.8 V ILEAKCHRG CHRG Pin Leakage Current V IN = 0, VCHRG = 6V l 1 mA ICHRG CHRG Pin Weak Pull-Down Current V CHRG = 1V, Charging, C/10 Reached 20 40 70 mA ORDER PART NUMBER LTC4052EMS8E-4.2 TOP VIEW MSE EXPOSED PAD PACKAGE 8-LEAD PLASTIC MSOP BAT GATE CHRG TIMER SENSE ACPR V IN GND Consult LTC Marketing for parts specified with wider operating temperature ranges. LTYY DC ELECTRICAL CHARACTERISTICSThe l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. VIN = 6V unless otherwise noted.
LTC4052-4.2 405242f TYPICAL PERFOR A CE CHARACTERISTICSUW Note 1: Absolute Maximum Ratings are those values beyond which the life of a device may be impaired. Note 2: Absolute Maximum Rating for GATE pin applies only to externally applied voltage. During normal operation the LTC4052-4.2’s internal charge pump can generate GATE pin voltage exceeding absolute maximum but it is internally current limited. Note 3: The LTC4052EMS8E-4.2 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the –40 °C to 85°C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 4: Junction temperature TJ is calculated from the ambient temperature TA and power dissipation PD according to the following formula: TJ = TA + (PD • qJA°C/W) Note 5. This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction temperature will exceed 125°C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability.
ELECTRICAL CHARACTERISTICS
ITRICKLE (mA) 4.205 4.200 4.195 4.190 4.185 4.180 4.175
4.170 VBAT (V)
TEMPERATURE (°C) –50 ICHRG (µA) 25 75
4052 G06
–25 0 50 100 125 TEMPERATURE (°C) –50 25 75
4052 G05
–25 0 50 100 125 TEMPERATURE (°C) –50 25 75
4052 G04
–25 0 50 100 125 TTIMER (%) 103 102 101 100 CTIMER= 0.1µF VIN (V)
4052 G03
3524.2 24.0 23.8 23.6 23.4 23.2 23.0 22.8
22.6 ITRICKLE (mA)
TEMPERATURE (°C) –50 25 75
4052 G02
–25 0 50 100 125 TEMPERATURE (°C) –50 25 75
4052 G01
–25 0 50 100 125 VTRICKLE (V) 2.47 2.46 2.45 2.44 2.43 2.42 VBAT = 2V TA = 25°C Trickle Charge Threshold Voltage vs Temperature Trickle Charge Current vs Temperature Trickle Charge Current vs Input Supply Voltage Normalized Timer Duration vs Temperature Battery Float Voltage vs Temperature CHRG Pin C/10 Pulldown Current vs Temperature
LTC4052-4.2 405242f PI FU CTIO S UU U SENSE (Pin 1): Overcurrent Sense Input. A sense resistor (RSENSE) should be connected from VIN to the SENSE pin to program the current limit level. When overcurrent limit is tripped, the pass transistor immediately turns off and turns back on after a 640ms time-out period (C TIMER = 0.1mF). The on-off cycle will continue as long as the overcurrent condition persists or until the timer runs out. If overcurrent protection is not needed, short SENSE to V IN. ACPR (Pin 2): AC Wall Adapter Present Open-Drain Out- put. When the input voltage (wall adapter) is applied to the LTC4052, this pin is pulled to ground by an internal N-channel MOSFET capable of driving an LED. V IN (Pin 3): Positive Input Supply Voltage (4.5V £ VIN £ 10V). Bypass this pin with a 1mF capacitor in series with a 4.7W resistor. GND (Pin 4): Electrical Ground Connection and provides a thermal path from the IC to the PC board copper. The exposed backside of the package is also ground and must be soldered to the PC board for maximum power dissipa- tion. TIMER (Pin 5): Timer Set Pin. The timer period is pro- grammed by a capacitor (C TIMER) to ground. The timer period is: tTIMER = (CTIMER • 3Hr)/(0.1mF). The minimum ON time, minimum OFF time and the overcurrent time-out period all scale with tTIMER. CHRG (Pin 6): Charge Status Open-Drain Output. When a depleted battery is being charged, the CHRG pin is pulled to ground by an internal N-channel MOSFET capable of driving an LED. Once the duty cycle at the GATE pin drops below 10%, the N-MOSFET turns off and a weak 40 mA current source to ground turns on to indicate a near end- of-charge C/10 condition. When a time-out occurs or the input supply is removed, the CHRG pin becomes high impedance. GATE (Pin 7): Gate Drive Output Pin for Internal and External Pass Transistors. An external N-MOSFET transis- tor can be connected in parallel with the internal transistor to reduce the on-resistance for higher charge current. In this case, an external blocking diode on V IN is required to prevent damage to the battery if VIN is shorted to ground. A 10mA current source pulls this pin up to the charge pump voltage when turned on and a 40mA current source pulls it down to ground to turn it off. If an overcurrent condition is detected, the GATE pin is immediately pulled to ground. The voltage at this pin is internally clamped to 12V above the GND pin. TYPICAL PERFOR A CE CHARACTERISTICSUW TEMPERATURE (°C) –50 VIMAX (mV) 105.8 105.6 105.4 105.2 105.0 104.8 104.6 25 75
4053 G07
–25 0 50 100 125 TEMPERATURE (°C) –50 RDS(ON) (mΩ ) 100
4053 G08
–25 25 75 125 VBAT = 4V VBAT = 2.6V Overcurrent Sense Voltage Switch On-Resistance vs Temperature
LTC4052-4.2 405242f BLOCK DIAGRA W 4052 BD VFLOAT VRECHRG VMIN VMAX CHARGE PUMP TRIPLER LOGIC TIMERS +–+ – VIN SENSE GATE BAT 105mV45mV TRICKLE FAST 1.23V1.23V THERMAL SHUTDOWN REFERENCE OSCILLATOR 100ms FILTER 40µA VIN GND TIMER CHRG SLEEP ACPR CLK STOP C/10 TEMP IMAX BAT 24mA 10mΩ PI FU CTIO S UU U A series RC network from the GATE to the V IN pin is required to control the slew rate at the V IN pin when the switch is turned on or off. The slew rate control prevents excessive current from the capacitor usually located in the wall adapter from flowing into the battery when the pass transistor turns on. BAT (Pin 8): Battery Sense Input Pin. An internal resistor divider presets the final float voltage to 4.2V. If the BAT pin drops below 4.05V after the charge cycle has ended, the timer resets and a new charge cycle begins. This pin is clamped to 4.7V if the battery is disconnected while charging.
LTC4052-4.2 405242f OPERATIOU The LTC4052 is a complete lithium-ion battery pulse charger with an internal 0.35W N-MOSFET switch driven by an internal charge pump. The charge current is set by the current limit of the input supply (wall adapter). An external R SENSE sets the maximum allowable charge overcurrent and prevents a wall adapter with a high current limit from damaging the battery. If the current limit of the input supply is above I MAX, the charger will imme- diately turn off the N-MOSFET switch and will retry after 640ms, thus reducing the average charge current to approximately 1% of the overcurrent value (C TIMER = 0.1mF). If the battery is disconnected while in full charge mode, the charge pump turns off when the voltage at the BAT pin rises above 4.7V and turns back on when the voltage drops below the float voltage. A charge cycle begins when the voltage at the V IN pin rises above the BAT pin by 45mV. The charger will go into trickle charge mode if the battery voltage is below 2.45V. The trickle charge current is preset to 24mA and is provided by an internal current source. In trickle mode, both the pass transistor and charge pump are off. When the cell voltage exceeds 2.45V, the charger goes into full charge mode. In this mode, the charge pump turns on and ramps up the gate voltage of the pass transistor turning it on. The current limited voltage at the V IN pin will ramp down to VBAT plus the voltage drop across the pass transistor and RSENSE, thus reducing the power dissipa- tion in the pass transistor. The charge current is deter- mined by the current limit of the input supply. When the battery voltage reaches the final float voltage, the pass transistor turns off for 100ms (minimum off- time). It remains off as long as the battery voltage stays above the float voltage after the 100ms off-time. After the minimum off-time, if the battery voltage drops below the float voltage, the pass transistor turns back on for at least 400ms (minimum on-time). As the battery approaches full charge, the off-time will get longer and the on-time will stay at 400ms. When the N-MOSFET switch is on, the voltage at the BAT pin will be slightly higher than the final float voltage due to the ESR associated with the battery pack. This voltage level should not be high enough to turn on the overvoltage protection circuitry often located in the battery pack. When the duty cycle at the GATE pin drops below 10%, a comparator turns off the N-FET at the CHRG pin and connects a weak current source (40mA) to ground to indicate a near end-of-charge C/10 condition. The pulse charging will continue until the timer stops. An external capacitor at the TIMER pin sets the total charge time, the minimum on- and off-time and the overcurrent retry period. After a time-out has occurred, the charge cycle terminates and the CHRG pin is forced high imped- ance. After the charging stops, if the battery voltage drops below 4.05V due to external loading or internal battery leakage current, a new charge cycle will automatically resume.
the charge current (input supply current limit). pin output is then forced to a high impedance state. can distinguish all three states. See Figure 1.
4052 F01
Figure 1. Interfacing with Microprocessor charging a battery, the CHRG pin is high impedance.
- Force the digital output pin, OUT, high and read the logic
- If the IN pin is high, force the OUT pin to be high
- If the logic level at the IN pin is high, the charge cycle has
4052 TA0210µA/C
Figure 2. Slew Rate at GATE and VIN Pins is required in series with the battery or the input supply. the input supply is first applied. source to ground will start pulling the GATE voltage down. in a controlled manner (Figure 2). source voltage rating should be 16V or more.
- Input supply quiescent current multiplied by the input
- The voltage drop across the switch (SENSE pin to BAT
mounted nearby must also be considered. recommended to increase the effectiveness of the heat sink.
LTC4052-4.2 405242f In addition, feedthrough vias or plated through holes (lo- cated directly beneath the package and elsewhere) connect- ing internal copper and backside copper layers help transfer and spread the heat generated by the package. Calculating Junction Temperature Example: Find the maximum junction temperature for a battery voltage of 4V (V IN will collapse to approximately VBAT in the full charge mode), charge current of 1A and a maximum ambient temperature of 75°C. The power dissipated by the IC is: P=( I BAT • IBAT • RDS(ON)) + (VIN • IIN) = 0.35 + 0.003 = 0.353W The LTC4052 is available in an enhanced 8-pin MSOP package which features an exposed copper pad on the bottom of the package allowing it to be soldered directly to the PC board copper for maximum heat transfer. This greatly reduces the thermal resistance and increases the power handling capability when compared to a standard MSOP package. The junction to ambient thermal resis- tance of this package when the backside of the package is APPLICATIO S I FOR ATIOWU UU soldered to the PC board is approximately 35 °C/W de- pending on the copper area. The junction temperature rise above ambient will be approximately: The maximum junction temperature will be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or: TJMAX = 85°C + 12.36°C = 97.36°C ACPR Output Pin When the input voltage is 45mV higher than the voltage at the BAT pin, the ACPR pin is pulled to ground to indicate that the input supply (wall adapter) is applied. After the input supply is removed, this pin will become high imped- ance. An internal 100ms filter prevents the LTC4052 from turning off if the voltage at the V IN pin rings and gets too close to VBAT due to parasitic inductance. Stop Charging The charger is off when the voltage at the VIN pin is less than 45mV above V BAT (sleep mode). The charge pump and the internal pass transistor are turned off, and the internal resistor divider is disconnected to reduce the current drain on the battery in the sleep mode.
LTC4052-4.2 405242f 10k4.7Ω RSENSE 25mΩ 1-CELL 4.2V Li-Ion BATTERY Si2302DS CHARGE STATUS CHRG ACPR SENSE BAT TIMER CTIMER 0.1µF GND VIN LTC4052 GATE 1µF 0.047µF 0.022µF MBRS120T3 VIN = 5V TO 10V WITH 2A CURRENT LIMIT
4052 TA03
External N-MOSFET for Higher Charge Current UTYPICAL APPLICATIO
LTC4052-4.2 405242f PACKAGE DESCRIPTIO U 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1662) MSOP (MS8E) 0802 0.53 – 0.015 (.021 – .006) SEATING PLANE NOTE: 1. DIMENSIONS IN MILLIMETER/(INCH) 2. DRAWING NOT TO SCALE 3. DIMENSION DOES NOT INCLUDE MOLD FLASH, PROTRUSIONS OR GATE BURRS. MOLD FLASH, PROTRUSIONS OR GATE BURRS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 4. DIMENSION DOES NOT INCLUDE INTERLEAD FLASH OR PROTRUSIONS. INTERLEAD FLASH OR PROTRUSIONS SHALL NOT EXCEED 0.152mm (.006") PER SIDE 5. LEAD COPLANARITY (BOTTOM OF LEADS AFTER FORMING) SHALL BE 0.102mm (.004") MAX 0.18 (.077) 0.254 (.010) 1.10 (.043) MAX 0.22 – 0.38 (.009 – .015) TYP 0.13 – 0.076 (.005 – .003) 0.86 (.034) REF 0.65 (.0256) BSC 0° – 6° TYP DETAIL “A” DETAIL “A” GAUGE PLANE 12 3 4 4.90 – 0.15 (1.93 – .006) BOTTOM VIEW OF EXPOSED PAD OPTION 7 6 5 3.00 – 0.102 (.118 – .004) (NOTE 3) 3.00 – 0.102 (.118 – .004) NOTE 4 0.52 (.206) REF 1.83 – 0.102 (.072 – .004) 2.06 – 0.102 (.080 – .004) 5.23 (.206) MIN 3.2 – 3.45 (.126 – .136) 2.083 – 0.102 (.082 – .004) 2.794 – 0.102 (.110 – .004) 0.889 – 0.127 (.035 – .005) RECOMMENDED SOLDER PAD LAYOUT 0.42 – 0.04 (.0165 – .0015) TYP 0.65 (.0256) BSC Information furnished by Linear Technology Corporation is believed to be accurate and reliable. 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.
LTC4052-4.2 405242f Linear Technology Corporation 1630 McCarthy Blvd., Milpitas, CA 95035-7417 (408) 432-1900 l FAX: (408) 434-0507 l www.linear.com ª LINEAR TECHNOLOGY CORPORATION 2001 LT/TP 0303 2K • PRINTED IN USA 10k 1-CELL 4.2V 600mA Li-Ion BATTERY CHRG ACPR SENSE BAT TIMER CTIMER 0.1µF GND VIN VIN = 5V TO 10V WITH 600mA CURRENT LIMIT LTC4052 GATE 0.047µF 0.022µF
4052 TA04
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