LTC4052-42 LINEAR | Alldatasheet
Document overview
- Manufacturer or author: Provided By ALLDATASHEET.COM(FREE DATASHEET DOWNLOAD SITE)
- PDF pages: 8
Technical content
LTC4052-4.2 405242i 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. TYPICAL APPLICATIO U Lithium-Ion Battery Pulse Charger with Overcurrent Protection July 2002 Final Electrical Specifications Single Cell 4.2V, 1A, Standalone Li-Ion Battery Charger
FEATURES
4052 is a complete standalone pulse charger with integrated MOSFET for 1-cell lithium-ion batteries. An external sense resistor provides maximum charge current 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 ends 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 wallpack current. Removing the input voltage puts the LTC4052 into a sleep mode, dropping the battery current drain to less than 1mA (maximum). The LTC4052 is available in a tiny 8-pin thermally enhanced MSOP package. n Standalone Lithium-Ion Battery Charger n Personal Information Appliances n Cellular Telephones n Cradle Chargers , LTC and LT are registered trademarks of Linear Technology Corporation. n Complete Standalone Pulse Charger for 1-Cell Lithium-Ion Batteries n Requires No Microcontroller n Internal 0.35W NMOS Switch n Sense Resistor Limits Maximum Current for Safety n Programmable Charge Termination Timer for Maximum Capacity Charging n No Blocking Diode Required n 1% Float Voltage Accuracy n Near End-of-Charge (C/10) Detection 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 Small 8-Pin 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 405242i 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 Supply Voltage Wall Adapter Open Circuit Voltage l 4.5 10 V IIN Supply Current Fast 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 Voltage l 90 105 120 mV ITRICKL Trickle Charge Current V BAT = 2V l 14 24 34 mA VTRICKL Trickle Charge Trip Threshold 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, Fast Charge Mode –10 % ILEAK Battery Leakage Through Charger V BAT = 4V, VIN = 0V l 1 mA VSLEEP Sleep Threshold (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 Pull-Down Current V CHRG = 1V, Charging, C/10 Reached 20 40 70 mA TSHDN Thermal Shutdown Temperature 140 °C DTSHDN Thermal Shutdown Hysteresis 5 °C 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 405242i 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 current 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 VIN. ACPR (Pin 2): Wall Adapter AC 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. Use large copper pads and traces for maximum heat transfer. TIMER (Pin 5): Timer Set Pin. The timer period is set 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 is required to prevent damage to the battery if V IN is shorted to ground. A 10mA current source pulls this pin up to the charge pump potential 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. 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 located in the wall adapter from flowing into the battery when the pass transistor is turned on. BAT (Pin 8): Battery Sense Input Pin. This pin is clamped to 4.7V if the battery is disconnected while charging. 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. 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)
ELECTRICAL CHARACTERISTICS
LTC4052-4.2 405242i BLOCK DIAGRA W 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 the wrong current limit from damaging the battery. If the current limit of the input supply is above IMAX, the charger will imme- diately terminate charging and will retry after 640ms (CTIMER = 0.1mF). If the battery is disconnected while in fast charge mode, the charge pump will be turned off when the voltage at the BAT pin rises above 4.7V and turned 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. OPERATIOU 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
LTC4052-4.2 405242i OPERATIOU Input Voltage (Wall Adapter) The input voltage to the LTC4052 must have some method of current limit capability. The current limit level of the input power source must be lower than the overcurrent limit (I MAX) set by the sense resistor IMAX = 105mV/(RSENSE + 10mW ). The 10mW represents bond wire resistance internal to the IC. If a wall adapter without current limit is used, or the current limit level is above I MAX, the charger will turn on briefly and then immediately turn off after the overcurrent condition is detected. This cycle will be resumed every 640ms (C TIMER = 0.1mF) until the total charge time has run out. If overcurrent protection is not needed, short the SENSE pin to VIN. Trickle Charge and Defective Battery Detection At the beginning of the charge cycle, if the cell voltage is low (less than 2.45V) the charger goes into a 24mA trickle charge mode. If the low cell voltage persists for one quarter of the total charge time, the battery is considered defective and the charge cycle is terminated. The CHRG pin output is then forced to a high impedance state. Battery Charge Current The battery charge current is determined by the current limit of the input supply (wall adapter). However, this current must not exceed the maximum charge current, I MAX. If an overcurrent condition is detected, the charging is immediately terminated, the GATE pin is pulled to ground and the charge pump turns off. The charging will resume after a 640ms time off (C TIMER = 0.1mF). Programming the Timer The programmable timer is used to terminate the charge cycle and sets the minimum ON/OFF time and the overcurrent time-off period. The length of the timer is programmed by an external capacitor from the TIMER pin to ground. The total charge time is: Time (Hours) = (3 Hours)(C TIMER/0.1mF) or CTIMER = 0.1mF • Time (Hours)/3 (Hours) The timer starts when the input voltage (at least 40mV greater than V BAT) is applied. After a time-out has oc- curred, the charging stops and the CHRG pin becomes high impedance. APPLICATIO S I FOR ATIOWU UU When the cell voltage exceeds 2.45V, the charger goes into fast charge mode. In this mode, the charge pump turns on and ramps up the gate voltage of the pass transistor turning it on. The voltage at the V IN pin then ramps 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. The voltage at the BAT pin will be slightly higher than the final float voltage due to the ESR associ- ated with the battery pack. This voltage level should not 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 4V, due to external loading or internal leakage, a new charge cycle will automatically resume.
nates. C/10 detection is disabled in trickle charge mode. mately 140°C with 5°C of thermal hysteresis. the input supply is first applied. source to ground will start pulling the GATE voltage down. at a controlled manner (Figure 2). source breakdown voltage should be rated for 16V or more.
4052 F01
Figure 1. Interfacing with Microprocessor can distinguish all three states. See Figure 1. 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
- Input supply current multiplied by the input voltage
- 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. and spread the heat generated by the package. ambient temperature of 75°C. close to VBAT due to parasitic inductance. current drain on the battery in the sleep mode.
4052 TA0210µA/C
Figure 2. Slew Rate at GATE and VIN Pins
LTC4052-4.2 405242i 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 0702 1.5K • PRINTED IN USA PACKAGE DESCRIPTIO U 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 TYPICAL APPLICATIO SU 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
Minimum Component Count 4.2V Li-Ion Battery Charger MSOP (MS8E) 1001 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) 0.13 – 0.05 (.005 – .002) 0.86 (.34) REF 0.65 (.0256) BCS 0° – 6° TYP DETAIL “A” DETAIL “A” GAUGE PLANE 12 3 4 4.88 – 0.1 (.192 – .004) 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 8-Lead Plastic MSOP (Reference LTC DWG # 05-08-1662) RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1510-5 500kHz CC/CV Battery Charger Most Compact, Up to 1.5A, Charges NiCd, NiMH, Li-Ion Cells LTC1729 Termination Controller for Li-Ion Time or Charge Current Termination, Automatic Charger/Battery Detection Status Output, Preconditioning, 8-Lead MSOP LTC1730 Li-Ion Battery Pulse Charger with Thermistor Interface Battery Temperature Sensing, FAULT Output, SO-8 and SSOP-16 Packag es LTC1731 Li-Ion Battery Charger Controller CC/CV Charges Li-Ion Cells, 8-Lead MSOP LTC1732 Li-Ion Battery Charger Controller CC/CV Charges Li-Ion Cells, Automatic Battery Detection, 10-Lead MSOP LTC1733 Li-Ion Battery Charger with Thermal Regulation Standalone Charger, Constant-Current/Constant-Voltage/ Constant-Temperature, Integrated MOSFET, No External Sense Resistor or Blocking Diodes LTC1734 ThinSOT TM Li-Ion Battery Charger Only Two External Components, Up to 700mA I CHARGE, No Reverse Current Diode Required, No Sense Resistor Required LTC4050 Li-Ion Battery Charger Controller with Thermistor Interface Drives External MOSFET, 10-Lead MSOP ThinSOT is a trademark of Linear Technology Corporation