DESCRIPTIO July 2002 Complete Standalone Pulse Charger 1-Cel
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LTC4052-4.2 Lithium-Ion Battery Pulse Charger with Overcurrent Protection
DESCRIPTIO
July 2002
Complete Standalone Pulse Charger 1-Cell Lithium-Ion Batteries Requires Microcontroller Internal 0.35 NMOS Switch Sense Resistor Limits Maximum Current Safety Programmable Charge Termination Timer Maximum Capacity Charging Blocking Diode Required Float Voltage Accuracy Near End-of-Charge (C/10) Detection Output Battery Drain when Input Supply Removed Automatic Trickle Charge Battery Automatic Battery Refresh Thermal Shutdown Protection Small 8-Pin Thermally Enhanced MSOP Package
LTC4052 complete standalone pulse charger with integrated MOSFET 1-cell lithium-ion batteries. external sense resistor provides maximum charge current limiting safety precaution against user connecting wall adapter with incorrect current limit. internal MOSFET prevents reverse battery current from flowing input voltage shorted ground, eliminating need blocking diode. battery accepts charge approaches programmed float voltage, internal MOSFET begins switching with duty cycle gradually decreasing battery approaches fully charged condition. programmable timer ends charge cycle. near end-of-charge C/10 condition indicated CHRG when average charge current falls one-tenth wallpack current. Removing input voltage puts LTC4052 into sleep mode, dropping battery current drain less than (maximum). LTC4052 available tiny 8-pin thermally enhanced MSOP package.
registered trademarks Linear Technology Corporation.
APPLICATIO
Standalone Lithium-Ion Battery Charger Personal Information Appliances Cellular Telephones Cradle Chargers
TYPICAL APPLICATIO
4.5V WITH CURRENT LIMIT
Single Cell 4.2V, Standalone Li-Ion Battery Charger
LTC4052 GATE CHRG ACPR SENSE TIMER
0.047µF RSENSE 0.05
BATTERY VOLTAGE
TIME (HOURS) C/10 CONSTANT CURRENT PULSING CURRENT CHARGE CYCLE ENDS
PRESENT
0.022µF
1-CELL 4.2V Li-Ion BATTERY
CTIMER 0.1µF
4052 TA01
CHRG
CHARGE CURRENT
CHARGE STATUS
Information furnished Linear Technology Corporation believed accurate reliable. However, responsibility assumed use. Linear Technology Corporation makes representation that interconnection circuits described herein will infringe existing patent rights.
LTC4052 Charge Profile
4052 TA01b
405242i
LTC4052-4.2
ABSOLUTE
(Note
RATI
PACKAGE/ORDER ATIO
VIEW SENSE ACPR GATE CHRG TIMER
Input Supply Voltage (VIN). Voltage 0.3V GATE (Note 0.3V SENSE, TIMER 0.3V +0.3V CHRG, ACPR 0.3V SENSE, Peak Current 1.5A Operating Temperature Range (Note 40°C 85°C Junction Temperature (Note 125°C Storage Temperature Range 65°C 150°C Lead Temperature (Soldering, sec). 300°C
ORDER PART NUMBER LTC4052EMS8E-4.2 PART MARKING LTYY
EXPOSED PACKAGE 8-LEAD PLASTIC MSOP
TJMAX 125°C, 35°C/W EXPOSED GROUND. (MUST SOLDERED PCB).
Consult Marketing parts specified with wider operating temperature ranges.
ELECTRICAL CHARACTERISTICS
SYMBOL VBAT VRECHRG VMARGIN VIMAX ITRICKL VTRICKL RDS(ON) VGATE TTIMER ILEAK VSLEEP VACPR LEAKACPR VCHRG LEAKCHRG ICHRG TSHDN TSHDN PARAMETER Supply Voltage Supply Current Battery Float Voltage Recharge Battery Voltage Threshold VBAT VRECHRG Margin Overcurrent Trip Voltage Trickle Charge Current Trickle Charge Trip Threshold Internal Switch On-Resistance GATE Voltage TIMER Period Accuracy Battery Leakage Through Charger Sleep Threshold ACPR Output Voltage ACPR Leakage Current CHRG Output Voltage CHRG Leakage Current CHRG Pull-Down Current Thermal Shutdown Temperature Thermal Shutdown Hysteresis VBAT VBAT Rising VBAT 2.6V VBAT VBAT 2.6V VBAT CONDITIONS
denotes specifications which apply over full operating temperature range, otherwise specifications 25°C. unless otherwise noted.
4.242 4.242 4.110 4.110 2.55
UNITS
Wall Adapter Open Circuit Voltage Fast Charge Mode 85°C Battery Voltage Falling 85°C
4.158 4.137 3.990 3.969 2.35 4.200 4.200 4.050 4.050 2.45 0.45 0.35 10.5
CTIMER 0.1µF, Fast Charge Mode VBAT (VIN VBAT) High (VIN VBAT) High IACPR VACPR ICHRG 3mA, Charging, C/10 Reached VCHRG VCHRG Charging, C/10 Reached
405242i
LTC4052-4.2
ELECTRICAL CHARACTERISTICS
Note Absolute Maximum Ratings those values beyond which life device impaired. Note Absolute Maximum Rating GATE applies only externally applied voltage. During normal operation LTC4052-4.2's internal charge pump generate GATE voltage exceeding absolute maximum internally current limited. Note LTC4052EMS8E-4.2 guaranteed meet performance specifications from 70°C. Specifications over 40°C 85°C operating temperature range assured design, characterization correlation with statistical process controls. Note Junction temperature calculated from ambient temperature power dissipation according following formula: JA°C/W)
CTIO
SENSE (Pin Overcurrent Sense Input. sense resistor (RSENSE) should connected from SENSE program current limit level. When current limit tripped, pass transistor immediately turns turns back after 640ms time-out period (CTIMER 0.1µF). on-off cycle will continue long overcurrent condition persists until timer runs out. overcurrent protection needed, short SENSE VIN. ACPR (Pin Wall Adapter Present Open-Drain Output. When input voltage (wall adapter) applied LTC4052, this pulled ground internal N-channel MOSFET capable driving LED. (Pin Positive Input Supply Voltage (4.5V 10V). Bypass this with capacitor series with resistor. (Pin Electrical Ground Connection provides thermal path from board copper. large copper pads traces maximum heat transfer. TIMER (Pin Timer Pin. timer period capacitor (CTIMER) ground. timer period tTIMER (CTIMER 3Hr)/(0.1µF). minimum time, minimum time overcurrent time-out period scale with tTIMER. CHRG (Pin Charge Status Open-Drain Output. When depleted battery being charged, CHRG pulled ground internal N-channel MOSFET capable driving LED. Once duty cycle GATE drops below 10%, N-MOSFET turns weak 40µA current source ground turns indicate near endof-charge C/10 condition. When time-out occurs input supply removed, CHRG becomes high impedance. GATE (Pin Gate Drive Output Internal External Pass Transistors. external N-MOSFET transistor connected parallel with internal transistor reduce on-resistance higher charge current. this case, external blocking diode required prevent damage battery shorted ground. 10µA current source pulls this charge pump potential when turned 40µA current source pulls down ground turn off. overcurrent condition detected, GATE immediately pulled ground. voltage this internally clamped above pin. series network from GATE required control slew rate when switch turned off. slew rate control prevents excessive current from capacitor located wall adapter from flowing into battery when pass transistor turned (Pin Battery Sense Input Pin. This clamped 4.7V battery disconnected while charging. internal resistor divider presets final float voltage 4.2V. drops below 4.05V after charge cycle ended, timer resets charge cycle begins.
405242i
LTC4052-4.2
BLOCK DIAGRA
45mV
100ms FILTER
TIMER
OSCILLATOR
CHRG
40µA
THERMAL SHUTDOWN
REFERENCE
OPERATIO
LTC4052 complete lithium-ion battery pulse charger with internal 0.35 N-MOSFET switch driven internal charge pump. charge current current limit input supply (wall adapter). external RSENSE sets maximum allowable charge overcurrent prevents wall adapter with wrong current limit from damaging battery. current limit input supply above IMAX, charger will immediately terminate charging will retry after 640ms (CTIMER 0.1µF). battery disconnected while
ACPR 105mV SLEEP IMAX
SENSE
24mA CHARGE PUMP TRIPLER GATE
TRICKLE
FAST VMIN
STOP
VRECHRG LOGIC TIMERS
C/10
VFLOAT
TEMP
VMAX
1.23V
1.23V
4052
fast charge mode, charge pump will turned when voltage rises above 4.7V turned back when voltage drops below float voltage. charge cycle begins when voltage rises above 45mV. charger will into trickle charge mode battery voltage below 2.45V. trickle charge current preset 24mA provided internal current source. trickle mode, both pass transistor charge pump off.
405242i
LTC4052-4.2
OPERATIO
When cell voltage exceeds 2.45V, charger goes into fast charge mode. this mode, charge pump turns ramps gate voltage pass transistor turning voltage then ramps down VBAT plus voltage drop across pass transistor RSENSE, thus reducing power dissipation pass transistor. charge current determined current limit input supply. When battery voltage reaches final float voltage, pass transistor turns 100ms (minimum offtime). remains long battery voltage stays above float voltage after 100ms off-time. After minimum off-time, battery voltage drops below float voltage, pass transistor turns back least 400ms (minimum on-time). battery approaches full charge, off-time will longer on-time will
APPLICATIO ATIO
Input Voltage (Wall Adapter)
input voltage LTC4052 must have some method current limit capability. current limit level input power source must lower than overcurrent limit (IMAX) sense resistor IMAX 105mV/(RSENSE 10m). represents bond wire resistance internal wall adapter without current limit used, current limit level above IMAX, charger will turn briefly then immediately turn after overcurrent condition detected. This cycle will resumed every 640ms (CTIMER 0.1µF) until total charge time out. overcurrent protection needed, short SENSE VIN. Trickle Charge Defective Battery Detection beginning charge cycle, cell voltage (less than 2.45V) charger goes into 24mA trickle charge mode. cell voltage persists quarter total charge time, battery considered defective charge cycle terminated. CHRG output then forced high impedance state.
stay 400ms. voltage will slightly higher than final float voltage associated with battery pack. This voltage level should turn overvoltage protection circuitry often located battery pack. When duty cycle GATE drops below 10%, comparator turns N-FET CHRG connects weak current source (40µA) ground indicate near end-of-charge C/10 condition. pulse charging will continue until timer stops. external capacitor TIMER sets total charge time, minimum off-time overcurrent retry period. After time-out occurred, charge cycle terminates CHRG forced high impedance. After charging stops, battery voltage drops below external loading internal leakage, charge cycle will automatically resume. Battery Charge Current battery charge current determined current limit input supply (wall adapter). However, this current must exceed maximum charge current, IMAX. overcurrent condition detected, charging immediately terminated, GATE pulled ground charge pump turns off. charging will resume after 640ms time (CTIMER 0.1µF). Programming Timer programmable timer used terminate charge cycle sets minimum ON/OFF time overcurrent time-off period. length timer programmed external capacitor from TIMER ground. total charge time Time (Hours) Hours)(CTIMER/0.1µF) CTIMER 0.1µF Time (Hours)/3 (Hours) timer starts when input voltage least 40mV greater than VBAT) applied. After time-out occurred, charging stops CHRG becomes high impedance.
405242i
LTC4052-4.2
APPLICATIO ATIO
CHRG Status Output This open-drain output report three different charger conditions:
Charger Status Charging Charging Charging, C/10 Reached
LTC4052 CHRG 620k
4052
CHRG Behavior High Impedance Strong Pulldown Weak 40µA Pulldown
MICROPROCESSOR
Figure Interfacing with Microprocessor
Using simple two-resistor network microprocessor distinguish three states. Figure When LTC4052 charging battery, internal NMOSFET pulls CHRG ground. When C/10 reached, strong NMOS pulldown replaced weak 40µA current source pulldown. When LTC4052 charging battery, CHRG high impedance. Using network Figure microprocessor determine charger state using following procedure: Force digital output pin, OUT, high read logic value digital input, reads low, charger cycle progress. high, force high impedance, then read logic level again. low, charge cycle still progress, timer still running, charge current dropped below programmed value indicating that charge cycle nearly complete. logic level high, charge cycle ended. Near End-of-Charge C/10 Detection LTC4052 includes comparator monitor duty cycle GATE detect when battery nearing
full charge. When duty cycle falls below 10%, comparator trips turns N-MOSFET CHRG switches weak (40µA) current source ground. 40µA turns when charge cycle terminates. C/10 detection disabled trickle charge mode. Internal Pass Transistor N-channel MOSFET (0.35) included LTC4052 pass transistor. gate MOSFET controlled internal charge pump. body connected ground instead source terminal. There body diode from back pin; therefore, blocking diode required series with battery input supply. This will only reduce cost also reduce heat generated while fast charge mode. internal thermal shutdown circuit turns pass transistor when temperature exceeds approximately 140°C with thermal hysteresis. Gate Drive MOSFET gate drive consists regulated 10µA current source charge pump. series network required from GATE pin. When MOSFET turned voltage will start slewing down voltage equal VBAT plus voltage drop across pass transistor RSENSE. slew rate equal 10µA/C. ramping down slowly, inrush current reduced. resistor series with capacitor required limit transient current when input supply first applied. When charge pump turned off, 50µA current source ground will start pulling GATE voltage down. Once pass transistor off, voltage will begin slewing with rate equal 50µA/C. With this external capacitor, voltage ramping controlled manner (Figure higher current applications external power N-channel MOSFET connected parallel with internal pass transistor. Because charge pump output clamped above GND, external MOSFET gate source breakdown voltage should rated more.
405242i
LTC4052-4.2
APPLICATIO ATIO
10µA/C 50µA/C GATE VOLTAGE 10µA/C 50µA/C
10µA/C 50µA/C
4052 TA02
Figure Slew Rate GATE Pins with Network from GATE
Thermal Considerations power handling capability limited maximum rated junction temperature (125°C) amount board copper used heat sink. power dissipated device consists components: Input supply current multiplied input voltage voltage drop across switch (SENSE pin) multiplied charge current LTC4052 internal thermal shutdown designed protect from overtemperature conditions. continuous charging fast charge mode, maximum junction temperature must exceeded. important give careful consideration sources thermal resistance from junction ambient. Additional heat sources mounted nearby must also considered. Surface mount packages rely primarily board copper dissipate heat generated package surrounding air. Since board copper heat sink, generous amounts copper surrounding package recommended increase effectiveness heat sink. addition, feedthrough vias plated through holes (located directly beneath package elsewhere) connecting internal copper backside copper layers help transfer spread heat generated package. Calculating Junction Temperature Example: Find maximum junction temperature battery voltage (VIN will collapse around VBAT fast charge mode), charge current maximum ambient temperature 75°C.
power dissipated (IBAT IBAT RDS(ON)) (VIN IIN) 0.35) 1mA) 0.35 0.004 0.354W LTC4052 available enhanced 8-pin MSOP package which features exposed copper bottom package allowing soldered directly board copper maximum heat transfer. This greatly reduces thermal resistance increases power handling capability when compared standard MSOP package. junction aimbient thermal resistance this package approximately 35°C/W depending copper area. junction temperature rise above ambient will approximately: (0.354W)(35°C/W) 12.39°C maximum junction temperature will equal maximum junction temperature rise above ambient plus maximum ambient temperature TJMAX 85°C 12.39°C 97.39°C ACPR Output When input voltage 45mV higher than voltage pin, ACPR pulled ground indicate that input supply (wall adapter) applied. After input supply removed, this will become high impedance. internal 100ms filter prevents LTC4052 from turning voltage rings gets close VBAT parasitic inductance. Stop Charging charger when voltage less than 45mV above VBAT (sleep mode). charge pump internal pass transistor turned off, internal resistor divider disconnected reduce current drain battery sleep mode.
405242i
LTC4052-4.2
TYPICAL APPLICATIO
External N-MOSFET Higher Charge Current
WITH CURRENT LIMIT MBRS120T3 PRESENT STATUS CHARGE STATUS LTC4052 SENSE CHRG ACPR TIMER CTIMER 0.1µF GATE 0.022µF 1-CELL 4.2V Li-Ion BATTERY Si2302DS 0.047µF RSENSE
PACKAGE DESCRIPTIO
2.794 0.102 (.110 .004) 0.889 0.127 (.035 .005)
5.23 (.206)
2.083 0.102 3.45 (.082 .004) (.126 .136)
0.42 0.04 (.0165 .0015)
0.65 (.0256)
NOTE: DIMENSIONS MILLIMETER/(INCH) DRAWING SCALE DIMENSION DOES INCLUDE MOLD FLASH, PROTRUSIONS GATE BURRS. MOLD FLASH, PROTRUSIONS GATE BURRS SHALL EXCEED 0.152mm (.006") SIDE DIMENSION DOES INCLUDE INTERLEAD FLASH PROTRUSIONS. INTERLEAD FLASH PROTRUSIONS SHALL EXCEED 0.152mm (.006") SIDE LEAD COPLANARITY (BOTTOM LEADS AFTER FORMING) SHALL 0.102mm (.004")
RELATED PARTS
PART NUMBER DESCRIPTION LT1510-5 LTC1729 LTC1730 LTC1731 LTC1732 LTC1733 500kHz CC/CV Battery Charger Termination Controller Li-Ion Li-Ion Battery Pulse Charger with Thermistor Interface Li-Ion Battery Charger Controller Li-Ion Battery Charger Controller Li-Ion Battery Charger with Thermal Regulation COMMENTS Most Compact, 1.5A, Charges NiCd, NiMH, Li-Ion Cells Time Charge Current Termination, Automatic Charger/Battery Detection Status Output, Preconditioning, 8-Lead MSOP Battery Temperature Sensing, FAULT Output, SO-8 SSOP-16 Packages CC/CV Charges Li-Ion Cells, 8-Lead MSOP CC/CV Charges Li-Ion Cells, Automatic Battery Detection, 10-Lead MSOP Standalone Charger, Constant-Temperature, Integrated MOSFET, External Sense Resistor Blocking Diodes Only External Components, 700mA ICHARGE, Reverse Current Diode Required, Sense Resistor Required Drives External MOSFET, 10-Lead MSOP
405242i LT/TP 0702 1.5K PRINTED
LTC1734 LTC4050
ThinSOTLi-Ion Battery Charger Li-Ion Battery Charger Controller with Thermistor Interface
ThinSOT trademark Linear Technology Corporation
Linear Technology Corporation
1630 McCarthy Blvd., Milpitas, 95035-7417
(408) 432-1900 FAX: (408) 434-0507
Minimum Component Count 4.2V Li-Ion Battery Charger
WITH 600mA CURRENT LIMIT LTC4052 SENSE CHRG ACPR TIMER CTIMER 0.1µF GATE 1-CELL 4.2V 600mA Li-Ion BATTERY
4052 TA04
0.047µF 0.022µF
4052 TA03
MS8E Package 8-Lead Plastic MSOP
(Reference 05-08-1662)
3.00 0.102 (.118 .004) (NOTE RECOMMENDED SOLDER LAYOUT DETAIL 4.88 (.192 .004) 3.00 0.102 (.118 .004) NOTE 0.52 (.206) BOTTOM VIEW EXPOSED OPTION 2.06 0.102 (.080 .004) 1.83 0.102 (.072 .004)
0.254 (.010) GAUGE PLANE
0.53 0.015 (.021 .006) DETAIL 0.18 (.077)
1.10 (.043)
0.86 (.34)
SEATING PLANE
0.22 0.38 (.009 .015)
0.65 (.0256)
0.13 0.05 (.005 .002)
MSOP (MS8E) 1001
www.linear.com
LINEAR TECHNOLOGY CORPORATION 2001
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