MAX8724ETI+T ,Low-Cost Multichemistry Battery ChargersFeaturesThe MAX1908/MAX8724/MAX8765/MAX8765A highly♦ ±0.5% Output Voltage Accuracy Using Internalin ..
MAX8725ETI ,28 V, multichemistry battery charger with automatic system power selectorFeatures♦ ±0.5% Accurate Charge Voltage (0°C to +85°C)The MAX1909/MAX8725 highly integrated control ..
MAX8725ETI+ ,Multichemistry Battery Chargers with Automatic System Power SelectorApplicationsNotebook and Subnotebook Computers Minimum Operating CircuitHand-Held Data TerminalsP3T ..
MAX8725ETI+ ,Multichemistry Battery Chargers with Automatic System Power SelectorElectrical Characteristics(Circuit of Figure 1, V = V = V = 18V, V = V = V = 12V, V = V = 1.8V, MOD ..
MAX8725ETI+T ,Multichemistry Battery Chargers with Automatic System Power SelectorFeatures• Precise Measurement Improves Safety andThe MAX1909/MAX8725 highly integrated control ICsP ..
MAX8727ETB ,TFT-LCD Step-Up DC-DC ConverterApplicationsOrdering InformationNotebook Computer DisplaysPART TEMP RANGE PIN-PACKAGELCD Monitor Pa ..
MB84VD21183EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
MB84VD21194EM-70PBS , Stacked MCP (Multi-Chip Package) FLASH MEMORY & SRAM CMOS
MB84VD22181FM-70PBS , 32M (X16) FLASH MEMORY & 4M (X16) STATIC RAM
MB84VD22182EE-90 ,32M (x 8/x16) FLASH MEMORY & 4M (x 8/x16) STATIC RAMFUJITSU SEMICONDUCTORDS05-50204-2EDATA SHEETStacked MCP (Multi-Chip Package) FLASH MEMORY & SRAMCMO ..
MB84VD22183EE-90 ,32M (x 8/x16) FLASH MEMORY & 4M (x 8/x16) STATIC RAMFEATURES• Power supply voltage of 2.7 to 3.3 V• High performance90 ns maximum access time (Flash)85 ..
MB84VD22184FM-70 , 32M (X16) FLASH MEMORY & 4M (X16) STATIC RAM
MAX1908ETI+-MAX1908ETI+T-MAX8724ETI+-MAX8724ETI+T-MAX8765AETI+-MAX8765AETI+T-MAX8765ETI+-MAX8765ETI+T
Low-Cost Multichemistry Battery Chargers
AVAILABLE
EVALUATION KIT AVAILABLE
General DescriptionThe MAX1908/MAX8724/MAX8765/MAX8765A highly
integrated, multichemistry battery-charger control ICs
simplify the construction of accurate and efficient charg-
ers. These devices use analog inputs to control charge
current and voltage, and can be programmed by the host
or hardwired. The MAX1908/MAX8724/MAX8765/
MAX8765A achieve high efficiency using a buck topology
with synchronous rectification.
The MAX1908/MAX8724/MAX8765/MAX8765A feature
input current limiting. This feature reduces battery
charge current when the input current limit is reached
to avoid overloading the AC adapter when supplying
the load and the battery charger simultaneously. The
MAX1908/MAX8724/MAX8765/MAX8765A provide out-
puts to monitor current drawn from the AC adapter (DC
input source), battery-charging current, and the pres-
ence of an AC adapter. The MAX1908’s conditioning
charge feature provides 300mA to safely charge deeply
discharged lithium-ion (Li+) battery packs.
The MAX1908 includes a conditioning charge feature
while the MAX8724/MAX8765/MAX8765Ado not.
The MAX1908/MAX8724/MAX8765/MAX8765A charge two
to four series Li+ cells, providing more than 5A, and are
available in a space-saving, 28-pin, thin QFN package (5mm×5mm). An evaluation kit is available to speed designs.
ApplicationsNotebook and Subnotebook Computers
Personal Digital Assistants
Handheld Terminals
Features±0.5% Output Voltage Accuracy Using Internal
Reference (±0.4% for MAX8765A, 2-/3-Cell Only)±4% Accurate Input Current Limiting±5% Accurate Charge CurrentAnalog Inputs Control Charge Current and
Charge VoltageOutputs for Monitoring
Current Drawn from AC Adapter
Charging Current
AC Adapter PresenceUp to 17.6V Battery-Voltage Set PointMaximum 28V Input Voltage> 95% EfficiencyShutdown Control InputCharge Any Battery Chemistry
Li+, NiCd, NiMH, Lead Acid, etc.
Low-Cost Multichemistry Battery ChargersIINP
CSSP
CSSN
DHI
BST
DLOV
SHDN
ICHG
ACIN
ACOK
REFIN
ICTL
GND161718192021
VCTLBATTCELLSCSINCSIPPGNDDLO654321
CCV
CCI
CCS
REF
CLSLDO
DCIN
MAX1908
MAX8724
MAX8765
MAX8765A
THIN QFNTOP VIEW
Pin Configuration
Ordering InformationMAX1908
MAX8724
MAX8765
MAX8765A
AC ADAPTER
INPUT
TO EXTERNAL
LOAD
LDO
FROM HOST μP
10μH
0.015Ω
BATT+
DCIN
REFIN
VCTL
ICTL
ACIN
ACOK
SHDN
ICHG
IINP
CCV
CCI
CCS
CELLS
LDO
BST
DLOV
DHI
DLO
PGND
CSIP
CSIN
BATT
REFCLSGND
CSSPCSSN
0.01Ω
Minimum Operating Circuit
PARTTEMP RANGEPIN-PACKAGE
MAX1908ETI+-40°C to +85°C28 Thin QFN-EP*
MAX8724ETI+-40°C to +85°C28 Thin QFN-EP*
MAX8765ETI+-40°C to +85°C28 Thin QFN-EP*
MAX8765AETI+-40°C to +85°C28 Thin QFN-EP*
+Denotes a lead(Pb)-free/RoHS-compliant package.
*EP = Exposed pad.
MAX1908/MAX8724/
MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
DCIN, CSSP, CSSN, ACOKto GND.......................-0.3V to +30V
BST to GND............................................................-0.3V to +36V
BST to LX..................................................................-0.3V to +6V
DHI to LX...................................................-0.3V to (VBST+ 0.3V)
LX to GND.................................................................-6V to +30V
BATT, CSIP, CSIN to GND.....................................-0.3V to +20V
CSIP to CSIN or CSSP to CSSN or
PGND to GND....................................................-0.3V to +0.3V
CCI, CCS, CCV, DLO, ICHG,
IINP, ACIN, REF to GND.......................-0.3V to (VLDO+ 0.3V)
DLOV, VCTL, ICTL, REFIN, CELLS, CLS,
LDO, SHDNto GND.............................................-0.3V to +6V
DLOV to LDO.........................................................-0.3V to +0.3V
DLO to PGND.........................................-0.3V to (VDLOV+ 0.3V)
LDO Short-Circuit Current...................................................50mA
Continuous Power Dissipation (TA= +70°C)
28-Pin Thin QFN (5mm ×5mm)
(derate 20.8mW/°C above +70°C) .........................1666.7mW
Operating Temperature Range ..........................-40°C to +85°C
Junction Temperature......................................................+150°C
Storage Temperature Range.............................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSCHARGE-VOLTAGE REGULATIONVVCTL = VREFIN -0.5 +0.5VVCTL = VREFIN/20 -0.5 +0.5Battery-Regulation Voltage
Accuracy
(MAX1908/MAX8724/MAX8765
(2, 3, or 4 Cells) and MAX8765A
(4 Cells Only))VVCTL = VLDO -0.5 +0.5%VVCTL = VREFIN -0.4 +0.4VVCTL = VREFIN/20 -0.4 +0.4 Battery-Regulation Voltage
Accuracy (MAX8765A, 2 or 3
Cells Only) VVCTL = VLDO -0.4 +0.4%VCTL Default Threshold VVCTL rising 4.0 4.1 4.2 VREFIN Range (Note 1) 2.5 3.6 VREFIN Undervoltage Lockout VREFIN falling 1.20 1.92 V
CHARGE-CURRENT REGULATIONCSIP-to-CSIN Full-Scale Current-
Sense Voltage VICTL = VREFIN 71.25 75 78.75 mVVICTL = VREFIN -5 +5VICTL = VREFIN x 0.6 -5 +5VICTL = VLDO -6 +6MAX8765/MAX8765A only; VICTL = VREFIN x
0.036 -45 +45Charging-Current Accuracy MAX8724 only; VICTL = VREFIN x 0.058 -33 +33%Charge-Current Gain Error
(MAX8765/MAX8765A Only) -2 +2 %Charge-Current Offset
(MAX8765/MAX8765A Only) -2 +2 mVICTL Default Threshold VICTL rising 4.0 4.1 4.2 VBATT/CSIP/CSIN Input Voltage
Range 0 19 V
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSVDCIN = 0V or VICTL = 0V or V SHDN = 0V 1 CSIP/CSIN Input Current Charging 400 650 µACycle-by-Cycle Maximum Current
Limit RS2 = 0.015mΩ 6.0 6.8 7.5 AICTL Power-Down Mode
Threshold Voltage
(MAX1908/MAX8724 Only) VVCTL rising REFIN/
100 REFIN/ REFIN/ VVVCTL = VICTL = 0 or 3V -1 +1 ICTL, VCTL Input Bias Current VDCIN = 0V, VVCTL = VICTL = VREFIN = 5V -1 +1 µAVDCIN = 5V, VREFIN = 3V -1 +1 REFIN Input Bias Current VREFIN = 5V -1 +1 µAICHG Transconductance
(MAX1908/MAX8724 Only) GICHG VCSIP - VCSIN = 45mV 2.7 3 3.3 µA/mVICHG Transconductance
(MAX8765/MAX8765A Only) GICHG VCSIP - VCSIN = 45mV 2.85 3 3.15 µA/mVICHG Transconductance Error
(MAX8765/MAX8765A Only) -5 +5 %ICHG Transconductance Offset
(MAX8765/MAX8765A Only) -5 +5 µAVCSIP - VCSIN = 75mV -6 +6VCSIP - VCSIN = 45mV -5 +5 ICHG Accuracy VCSIP - VCSIN = 5mV -40 +40%ICHG Output Current VCSIP - VCSIN = 150mV, VICHG = 0V 350 µAICHG Output Voltage VCSIP - VCSIN = 150mV, ICHG = open 3.5 V
INPUT-CURRENT REGULATIONCSSP-to-CSSN Full-Scale
Current-Sense Voltage 72 75 78 mVVCLS = VREF -4 +4VCLS = VREF/2 -7.5 +7.5 Input Current-Limit Accuracy VCLS = 1.1V (MAX8765/MAX8765A only) -10 +10%Input Current-Limit Gain Error
(MAX8765/MAX8765A Only) -2 +2 %Input Current-Limit Offset
(MAX8765/MAX8765A Only) -2 +2 mVCSSP, CSSN Input Voltage
Range 8 28 VVDCIN = 0V 0.1 1 CSSP, CSSN Input Current
(MAX1908/MAX8724 Only) VCSSP = VCSSN = VDCIN > 8V 350 600 µAVDCIN = 0V 0.1 1 CSSP Input Current
(MAX8765/MAX8765A Only) VCSSP = VCSSN = 28V VDCIN = 28V 400 650 µA
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSVDCIN = 0V 0.1 1 CSSN Input Current
(MAX8765/MAX8765A Only) VCSSP = VCSSN = 28V VDCIN = 28V 0.1 1 µACLS Input Range
(MAX1908/MAX8724 Only) 1.6 REF VCLS Input Range
(MAX8765/MAX8765A Only) 1.1 REF VCLS Input Bias Current VCLS = 2V -1 +1 µAIINP Transconductance
(MAX1908/MAX8724 Only) GIINP VCSSP - VCSSN = 75mV 2.7 3 3.3 µA/mVVCSSP - VCSSN = 75mV -5 +5 IINP Accuracy VCSSP - VCSSN = 37.5mV -7.5 +7.5 %IINP Transconductance
(MAX8765/MAX8765A Only) GIINP VCSSP - VCCSN = 75mV 2.82 3 3.18 µA/mVIINP Transconductance Error
(MAX8765/MAX8765A Only) -6 +6 %IINP Transconductance Offset
(MAX8765/MAX8765A Only) -10 +10 µAIINP Output Current VCSSP - VCSSN = 150mV, VIINP = 0V 350 µAIINP Output Voltage VCSSP - VCSSN = 150mV, VIINP = open 3.5 V
SUPPLY AND LDO REGULATORDCIN Input Voltage Range VDCIN 8 28 VVDCIN falling 7 7.4 DCIN Undervoltage-Lockout Trip
Point VDCIN rising 7.5 7.85 VDCIN Quiescent Current IDCIN 8.0V < VDCIN < 28V 3.2 6 mAVBATT = 19V, VDCIN = 0V 1 BATT Input Current IBATT VBATT = 2V to 19V, VDCIN = 19.3V 200 500 µALDO Output Voltage 8V < VDCIN < 28V, no load 5.25 5.4 5.55 VLDO Load Regulation 0 < ILDO < 10mA 34 100 mVLDO Undervoltage-Lockout Trip
Point VDCIN = 8V 3.20 4 5.15 V
REFERENCEREF Output Voltage 0 < IREF < 500µA 4.072 4.096 4.120 VREF Undervoltage-Lockout Trip
Point VREF falling 3.1 3.9 V
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSTRIP POINTSVDCIN falling, referred to VCSIN
(MAX1908/MAX8724 only) 50 100 150BATT Power-Fail Threshold VCSSP falling, referred to VCSIN
(MAX8765/MAX8765A only) 50 100 150mVBATT Power-Fail Threshold
Hysteresis 200 mVACIN rising (MAX8765/MAX8765A only) 2.028 2.048 2.068 ACIN Threshold ACIN rising (MAX1908/MAX8724 only) 2.007 2.048 2.089 VACIN Threshold Hysteresis 0.5% of REF 20 mVACIN Input Bias Current VACIN = 2.048V -1 +1 µA
SWITCHING REGULATORDHI Off-Time VBATT = 16V, VDCIN = 19V,
VCELLS = VREFIN 0.36 0.4 0.44 µsDHI Minimum Off-Time VBATT = 16V, VDCIN = 17V,
VCELLS = VREFIN 0.24 0.28 0.33 µsDHI Maximum On-Time 2.5 5 7.5 msDLOV Supply Current DLO low 5 10 µABST Supply Current DHI high 6 15 µABST Input Quiescent Current VDCIN = 0V, VBST = 24.5V,
VBATT = VLX = 20V 0.3 1 µALX Input Bias Current VDCIN = 28V, VBATT = VLX = 20V 150 500 µALX Input Quiescent Current VDCIN = 0V, VBATT = VLX = 20V 0.3 1 µADHI Maximum Duty Cycle 99 99.9 %Minimum Discontinuous-Mode
Ripple Current 0.5 ABattery Undervoltage Charge
Current VBATT = 3V per cell (RS2 = 15mΩ),
MAX1908 only, VBATT rising 150 300 450 mACELLS = GND, MAX1908 only, VBATT rising 6.1 6.2 6.3CELLS = open, MAX1908 only, VBATT rising 9.15 9.3 9.45 Battery Undervoltage Current
Threshold CELLS = VREFIN, MAX1908 only, VBATT rising 12.2 12.4 12.6VDHI On-Resistance High VBST - VLX = 4.5V, IDHI = +100mA 4 7 ΩDHI On-Resistance Low VBST - VLX = 4.5V, IDHI = -100mA 1 3.5 ΩDLO On-Resistance High VDLOV = 4.5V, IDLO = +100mA 4 7 ΩDLO On-Resistance Low VDLOV = 4.5V, IDLO = -100mA 1 3.5 Ω
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= 0°C to +85°C, unless otherwise noted. Typical values are at TA= +25°C.)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSERROR AMPLIFIERSGMV Amplifier Transconductance GMV V V C T L = V LD O, V BAT T = 16.8V ,E LLS = V RE F IN 0.0625 0.125 0.2500 µA/mVGMI Amplifier Transconductance GMI VICTL = V RE F IN , VCSIP - VCSIN = 75mV 0.5 1 2.0 µA/mVGMS Amplifier Transconductance GMS VCLS = VREF, VCSSP - VCSSN = 75mV 0.5 1 2.0 µA/mVCCI, CCS, CCV Clamp Voltage 0.25V < VCCV,CCS,CCI < 2V 150 300 600 mV
LOGIC LEVELSCELLS Input Low Voltage 0.4 VCELLS Input Open Voltage CELLS = open (VREFIN
/2) -
0.2VV R E F IN /( V R E F IN
/2) +
0.2V VCELLS Input High Voltage VREFIN 0.4V VCELLS Input Bias Current CELLS = 0V or V RE F IN -2 +2 µAACOK AND SHDNACOK Input Voltage Range 0 28 VACOK Sink Current V A COK = 0.4V, VACIN = 3V 1 mAACOK Leakage Current V A COK = 28V, VACIN = 0V 1 µASHDN Input Voltage Range 0 LDO VVSHDN = 0V OR VLDO -1 +1 SHDN Input Bias Current VSHDN = 0V OR VSHDN = 5V -1 +1 µASHDN Threshold V S HDN falling 22 23.5 25 % of
VREFINSHDN Threshold Hysteresis 1 % of
VREFIN
MAX1908/MAX8724/MAX8765/MAX8765A
ELECTRICAL CHARACTERISTICS(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure1a; TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSCHARGE-VOLTAGE REGULATIONVVCTL = VREFIN -0.6 +0.6VVCTL = VREFIN/20 -0.6 +0.6 Battery Regulation Voltage
Accuracy (2, 3, or 4 Cells) VVCTL = VLDO -0.6 +0.6%REFIN Range (Note 1) 2.5 3.6 VREFIN Undervoltage Lockout VREFIN falling 1.92 V
CHARGE CURRENT REGULATIONCSIP-to-CSIN Full-Scale Current-
Sense Voltage VICTL = VREFIN 70.5 79.5 mVVICTL = VREFIN -6 +6VICTL = VREFIN x 0.6 -7.5 +7.5VICTL = VLDO -7.5 +7.5MAX8765/MAX8765A only; VICTL = VREFIN x
0.036 -50 +50 Charging-Current Accuracy MAX8724 only;
VICTL = VREFIN x 0.058 -33 +33%Charge-Current Gain Error
(MAX8765/MAX8765A Only) -2 +2 %Charge-Current Offset
(MAX8765/MAX8765A Only) -2 +2 mVBATT/CSIP/CSIN Input Voltage
Range 0 19 VVDCIN = 0V or VICTL = 0V or VSHDN = 0V 1 CSIP/CSIN Input Current Charging 650 µACycle-by-Cycle Maximum Current
Limit IMAX RS2 = 0.015Ω 6.0 7.5 AICTL Power-Down Mode
Threshold Voltage
(MAX1908/MAX8724 Only) VICTL rising REFIN/
100 REFIN/ VICHG Transconductance
(MAX1908/MAX8724 Only) GICHG VCSIP - VCSIN = 45mV 2.7 3.3 µA/mVICHG Transconductance
(MAX8765/MAX8765A Only) GICHG VCSIP - VCSIN = 45mV 2.785 3.225 µA/mVICHG Transconductance Error
(MAX8765/MAX8765A Only) -7.5 +7.5 %ICHG Transconductance Offset
(MAX8765/MAX8765A Only) -6.5 +6.5 µA
Low-Cost Multichemistry Battery ChargersMAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSVCSIP - VCSIN = 75mV -7.5 +7.5VCSIP - VCSIN = 45mV -7.5 +7.5 ICHG Accuracy VCSIP - VCSIN = 5mV -40 +40%
INPUT-CURRENT REGULATIONCSSP-to-CSSN Full-Scale
Current-Sense Voltage 71.25 78.75 mVVCLS = VREF -5 +5VCLS = VREF/2 -7.5 +7.5 Input Current-Limit Accuracy VCLS = 1.1V (MAX8765/MAX8765A only) -10 +10%Input Current-Limit Gain Error
(MAX8765/MAX8765A Only) -2 +2 %Input Current-Limit Offset
(MAX8765/MAX8765A Only) -2 +2 mVCSSP, CSSN Input Voltage
Range 8 28 VVDCIN = 0V 1 CSSP, CSSN Input Current
(MAX1908/MAX8724 Only) VCSSP = VCSSN = VDCIN > 8V 600 µAVDCIN = 0V 1 CSSP Input Current
(MAX8765/MAX8765A Only) VCSSP = VCSSN = 28V VDCIN = 28V 650 µAVDCIN = 0V 1 CSSN Input Current
(MAX8765/MAX8765A Only) VCSSP = VCSSN = 28V VDCIN = 28V 1 µACLS Input Range
(MAX1908/MAX8724 Only) 1.6 REF VCLS Input Range
(MAX8765/MAX8765A Only) 1.1 REF VIINP Transconductance
(MAX1908/MAX8724 Only) GIINP VCSSP - VCSSN = 75mV 2.7 3.3 µA/mVIINP Transconductance
(MAX8765/MAX8765A Only) GIINP VCSSP - VCCSN = 75mV 2.785 3.225 µA/mVIINP Transconductance Error
(MAX8765/MAX8765A Only) -7.5 +7.5 %IINP Transconductance Offset
(MAX8765/MAX8765A Only) -12 +12 µAVCSSP - VCSSN = 75mV -7.5 +7.5 IINP Accuracy VCSSP - VCSSN = 37.5mV -7.5 +7.5 %
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSSUPPLY AND LDO REGULATORDCIN Input Voltage Range VDCIN 8 28 VDCIN Quiescent Current IDCIN 8.0V < VDCIN < 28V 6 mAVBATT = 19V, VDCIN = 0V 1 BATT Input Current IBATT VBATT = 2V to 19V, VDCIN = 19.3V 500 µALDO Output Voltage 8V < VDCIN < 28V, no load 5.25 5.55 VLDO Load Regulation 0 < ILDO < 10mA 100 mV
REFERENCEREF Output Voltage 0 < IREF < 500µA 4.065 4.120 V
TRIP POINTSVDCIN falling, referred to VCSIN
(MAX1908/MAX8724 only) 50 150BATT Power-Fail Threshold VCSSP falling, referred to VCSIN
(MAX8765/MAX8765A only) 50 150mVACIN rising (MAX8765/MAX8765A only) 2.028 2.068 ACIN Threshold ACIN rising (MAX1908/MAX8724 only) 2.007 2.089 V
SWITCHING REGULATORDHI Off-Time VBATT = 16V, VDCIN = 19V,
VCELLS = VREFIN 0.35 0.45 µsDHI Minimum Off-Time VBATT = 16V, VDCIN = 17V,
VCELLS = VREFIN 0.24 0.33 µsDHI Maximum On-Time 2.5 7.5 msDHI Maximum Duty Cycle 99 %Battery Undervoltage Charge
Current VBATT = 3V per cell (RS2 = 15mΩ),
MAX1908 only, VBATT rising 150 450 mACELLS = GND, MAX1908 only, VBATT rising 6.09 6.30CELLS = open, MAX1908 only, VBATT rising 9.12 9.45 Battery Undervoltage Current
Threshold CELLS = VREFIN, MAX1908 only, VBATT rising 12.18 12.60VDHI On-Resistance High VBST - VLX = 4.5V, IDHI = +100mA 7 ΩDHI On-Resistance Low VBST - VLX = 4.5V, IDHI = -100mA 3.5 ΩDLO On-Resistance High VDLOV = 4.5V, IDLO = +100mA 7 ΩDLO On-Resistance Low VDLOV = 4.5V, IDLO = -100mA 3.5 Ω
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
ELECTRICAL CHARACTERISTICS (continued)(VDCIN= VCSSP= VCSSN = 18V, VBATT= VCSIP= VCSIN= 12V, VREFIN= 3V, VVCTL= VICTL= 0.75 x VREFIN, CELLS = open, CLS =
REF, VBST- VLX= 4.5V, ACIN = GND = PGND = 0, CLDO= 1µF, LDO = DLOV, CREF= 1µF; CCI, CCS, and CCV are compensated
per Figure 1a; TA
= -40°C to +85°C, unless otherwise noted.) (Note 2)
PARAMETERSYMBOLCONDITIONS MIN TYP MAX UNITSERROR AMPLIFIERSGMV Amplifier Transconductance GMV V V C T L = V LD O, V BAT T = 16.8V ,E LLS = V RE F IN 0.0625 0.250 µA/mVGMI Amplifier Transconductance GMI VICTL = V RE F IN , VCSIP - VCSIN = 75mV 0.5 2.0 µA/mVGMS Amplifier Transconductance GMS VCLS = VREF, VCSSP - VCSSN = 75mV 0.5 2.0 µA/mVCCI, CCS, CCV Clamp Voltage 0.25V < VCCV,CCS,CCI < 2V 150 600 mV
LOGIC LEVELSCELLS Input Low Voltage 0.4 VCELLS Input Open Voltage CELLS = open (VREFIN
/2) -
0.2V ( V R E F IN
/2) +
0.2V VCELLS Input High Voltage VREFIN 0.4V VACOK AND SHDNACOK Input Voltage Range 0 28 VACOK Sink Current V ACOK = 0.4V, VACIN = 3V 1 mASHDN Input Voltage Range 0 LDO VSHDN Threshold V SHDN falling 22 25 % of
VREFIN
Note 1:If both ICTL and VCTL use default mode (connected to LDO), REFIN is not used and can be connected to LDO.
Note 2:Specifications to TA= -40°C are guaranteed by design and not production tested.
LOAD-TRANSIENT RESPONSE
(BATTERY INSERTION AND REMOVAL)MAX1908 toc01
1ms/div
IBATT
2A/div
VBATT
5V/div
VCCI
500mV/div
VCCV
500mV/div
ICTL = LDO
VCTL = LDO
CCV
CCI
LOAD-TRANSIENT RESPONSE
(STEP IN-LOAD CURRENT)MAX1908 toc02
1ms/div
VBATT
2V/div
VCCI
500mV/div
VCCS
500mV/div
16.8VLOAD
CURRENT
5A/div
ADAPTER
CURRENT
5A/div
ICTL = LDO
CHARGING CURRENT = 3A
VBATT = 16.8V
LOAD STEP = 0 TO 4A
CCS
CCS
CCICCI
VBATT
2V/div
CHARGE
CURRENT
2A/div
LOAD
CURRENT
5A/div
ADAPTER
CURRENT
5A/div
LOAD-TRANSIENT RESPONSE
(STEP IN-LOAD CURRENT)MAX1908 toc03
1ms/divICTL = LDO
CHARGING CURRENT = 3A
VBATT = 16.8V
LOAD STEP = 0 TO 4A
Typical Operating Characteristics(Circuit of Figure 1, VDCIN= 20V, TA= +25°C, unless otherwise noted.)
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery ChargersINDUCTOR
CURRENT
500mA/div
VDCIN
10V/div
VBATT
500mV/div
LINE-TRANSIENT RESPONSEMAX1908 toc04
10ms/divICTL = LDO
VCTL = LDO
ICHARGE = 3A
LINE STEP 18.5V TO 27.5V
LDO LOAD REGULATION
MAX1908 toc05
LDO CURRENT (mA)
LDO
ERROR (%)
VLDO = 5.4V
LDO LINE REGULATION
MAX1908 toc06
VIN (V)
LDO
ERROR (%)
ILDO = 0
VLDO = 5.4V
REF VOLTAGE LOAD REGULATION
MAX1908 toc07
REF CURRENT (μA)
REF
ERROR (%)
REF VOLTAGE ERROR vs. TEMPERATURE
MAX1908 toc08
TEMPERATURE (°C)
REF
ERROR (%)
EFFICIENCY vs. CHARGE CURRENT
MAX1908 toc09
CHARGE CURRENT (A)
EFFICIENCY (%)
VBATT = 16V
VBATT = 8V
VBATT = 12V
FREQUENCY vs. VIN - VBATT
MAX1908 toc10
(VIN - VBATT) (V)
FREQUENCY (kHz)
ICHARGE = 3A
VCTL = ICTL = LDO
3 CELLS
4 CELLS
OUTPUT V/I CHARACTERISTICS
MAX1908 toc11
BATT CURRENT (A)
BATT VOLTAGE ERROR (%)
2 CELLS
3 CELLS
4 CELLS
BATT VOLTAGE ERROR vs. VCTL
MAX1908 toc12
VCTL/REFIN (%)
BATT VOLTAGE ERROR (%)4 CELLS
REFIN = 3.3V
NO LOAD
Typical Operating Characteristics (continued)(Circuit of Figure1, VDCIN= 20V, TA= +25°C, unless otherwise noted.)
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery ChargersCURRENT-SETTING ERROR vs. ICTL
MAX1908 toc13
VICTL (V)
CURRENT-SETTING ERROR (%)
VREFIN = 3.3V
ICHG ERROR vs. CHARGE CURRENT
MAX1908 toc14
IBATT (A)
ICHG (%)
VBATT = 16V
VBATT = 12V
VBATT = 8V
VREFIN = 3.3V
IINP ERROR vs. SYSTEM LOAD CURRENT
MAX1908 toc15
SYSTEM LOAD CURRENT (A)
IINP ERROR (%)
IBATT = 0
IINP ERROR vs. INPUT CURRENT
MAX1908 toc16
INPUT CURRENT (A)
IINP ERROR (%)SYSTEM LOAD = 0
ERROR DUE TO SWITCHING NOISE
Typical Operating Characteristics (continued)(Circuit of Figure1, VDCIN= 20V, TA= +25°C, unless otherwise noted.)
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
Pin Description
PINNAMEFUNCTION1 DCIN Charging Voltage Input. Bypass DCIN with a 1µF capacitor to PGND.2 LDO D evi ce P ow er S up p l y. Outp ut of the 5.4V l i near r eg ul ator sup p l i ed fr om D C IN . Byp ass w i th a 1µF cap aci tor to GN D .3 CLS Source Current-Limit Input. Voltage input for setting the current limit of the input source.4 REF 4.096V Voltage Reference. Bypass REF with a 1µF capacitor to GND.5 CCS Input-Current Regulation Loop-Compensation Point. Connect a 0.01µF capacitor to GND.6 CCI Output-Current Regulation Loop-Compensation Point. Connect a 0.01µF capacitor to GND.7 CCV Voltage Regulation Loop-Compensation Point. Connect 1kΩ in series with a 0.1µF capacitor to GND.8 SHDN Shutdown Control Input. Drive SHDN logic low to shut down the MAX1908/MAX8724/MAX8765 MAX8765A.
Use with a thermistor to detect a hot battery and suspend charging.9 ICHG Charge-Current Monitor Output. ICHG is a scaled-down replica of the charger output current. Use ICHG to
monitor the charging current and detect when the chip changes from constant-current mode to constant-
voltage mode. The transconductance of (CSIP - CSIN) to ICHG is 3µA/mV.10 ACIN AC Detect Input. Input to an uncommitted comparator. ACIN can be used to detect AC-adapter presence.11 ACOK AC Detect Output. High-voltage open-drain output is high impedance when VACIN is less than VREF/2.12 REFIN Reference Input. Allows the ICTL and VCTL inputs to have ratiometric ranges for increased accuracy.13 ICTL Output Current-Limit Set Input. ICTL input voltage range is VREFIN/32 to VREFIN. The MAX1908/MAX8724 shut
down if ICTL is forced below VREFIN/100 while the MAX8765/MAX8765A does not. When ICTL is equal to
LDO, the set point for CSIP - CSIN is 45mV.14 GND Analog Ground15 VCTL Output Voltage-Limit Set Input. VCTL input voltage range is 0 to VREFIN. When VCTL is equal to LDO, the set
point is (4.2 x CELLS)V.16 BATT Battery Voltage Input17 CELLS Cell Count Input. Tri-level input for setting number of cells. GND = 2 cells, open = 3 cells, REFIN = 4 cells.18 CSIN Output Current-Sense Negative Input19 CSIP Output Current-Sense Positive Input. Connect a current-sense resistor from CSIP to CSIN.20 PGND Power Ground21 DLO Low-Side Power MOSFET Driver Output. Connect to low-side nMOS gate.22 DLOV Low-Side Driver Supply. Bypass DLOV with a 1µF capacitor to GND.23 LX High-Side Power MOSFET Driver Power-Return Connection. Connect to the source of the high-side nMOS.24 BST High-Side Power MOSFET Driver Power-Supply Connection. Connect a 0.1µF capacitor from LX to BST.25 DHI High-Side Power MOSFET Driver Output. Connect to high-side nMOS gate.26 CSSN Input Current-Sense Negative Input27 CSSP Input Current-Sense Positive Input. Connect a current-sense resistor from CSSP to CSSN.28 IINP Input-Current Monitor Output. IINP is a scaled-down replica of the input current. IINP monitors the total
system current. The transconductance of (CSSP - CSSN) to IINP is 3µA/mV.
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery Chargers
Detailed DescriptionThe MAX1908/MAX8724/MAX8765/MAX8765A include
all the functions necessary to charge Li+ batteries. A
high-efficiency synchronous-rectified step-down DC-DC
converter controls charging voltage and current. The
device also includes input-source current limiting and
analog inputs for setting the charge current and charge
voltage. Control charge current and voltage using the
ICTL and VCTL inputs, respectively. Both ICTL and
VCTL are ratiometric with respect to REFIN, allowing
compatibility with DACs or microcontrollers (µCs).
Ratiometric ICTL and VCTL improve the accuracy of the
charge current and voltage set point by matching VRE-
FINto the reference of the host. For standard applica-
tions, internal set points for ICTL and VCTL provide 3A
charge current (with 0.015Ωsense resistor), and 4.2V
(per cell) charge voltage. Connect ICTL and VCTL to
LDO to select the internal set points. The MAX1908
safely conditions overdischarged cells with 300mA (with
0.015Ωsense resistor) until the battery-pack voltage
exceeds 3.1V ×number of series-connected cells. The
SHDNinput allows shutdown from a microcontroller or
thermistor.
The DC-DC converter uses external n-channel
MOSFETs as the buck switch and synchronous rectifier
to convert the input voltage to the required charging
current and voltage. The Typical Application Circuit
shown in Figure 1 uses a µC to control charging cur-
rent, while Figure 2 shows a typical application with
charging voltage and current fixed to specific values
for the application. The voltage at ICTL and the value of
RS2 set the charging current. The DC-DC converter
generates the control signals for the external MOSFETs
to regulate the voltage and the current set by the VCTL,
ICTL, and CELLS inputs.
The MAX1908/MAX8724/MAX8765/MAX8765A feature
a voltage regulation loop (CCV) and two current regula-
tion loops (CCI and CCS). The CCV voltage regulation
loop monitors BATT to ensure that its voltage does not
exceed the voltage set by VCTL. The CCI battery cur-
rent regulation loop monitors current delivered to BATT
to ensure that it does not exceed the current limit set by
ICTL. A third loop (CCS) takes control and reduces the
battery-charging current when the sum of the system
load and the battery-charging input current exceeds
the input current limit set by CLS.
Setting the Battery-Regulation VoltageThe MAX1908/MAX8724/MAX8765/MAX8765A use a
high-accuracy voltage regulator for charging voltage.
The VCTL input adjusts the charger output voltage.
VCTL control voltage can vary from 0 to VREFIN, provid-
voltage. By limiting the adjust range to 10% of the regu-
lation voltage, the external resistor mismatch error is
reduced from 1% to 0.05% of the regulation voltage.
Therefore, an overall voltage accuracy of better than
0.7% is maintained while using 1% resistors. The per-
cell battery termination voltage is a function of the bat-
tery chemistry. Consult the battery manufacturer to
determine this voltage. Connect VCTL to LDO to select
the internal default setting VBATT= 4.2V ×number of
cells, or program the battery voltage with the following
equation:
CELLS is the programming input for selecting cell count.
Connect CELLS as shown in Table 2 to charge 2, 3, or 4
Li+ cells. When charging other cell chemistries, use
CELLS to select an output voltage range for the charger.
The internal error amplifier (GMV) maintains voltage
regulation (Figure 3). The voltage error amplifier is
compensated at CCV. The component values shown in
Figures 1 and 2 provide suitable performance for most
applications. Individual compensation of the voltage reg-
ulation and current regulation loops allows for optimal
compensation (see the Compensationsection).CELLSVVBATTVCTL
REFIN=×+×⎛⎜⎞⎟⎛⎜⎞⎟404.
Table 2. Cell-Count Programming
DESCRIPTIONMAX1908MAX8724MAX8765/
MAX8765AConditioning
Charge FeatureYesNoNo
ICTL Shutdown
ModeYesYesNo
ACOK Enable
Condition
REFIN must
be ready
REFIN must
be ready
Independent
of REFIN
Table 1. Versions Comparison
CELLSCELL COUNTGND2
Open3
VREFIN4
MAX1908/MAX8724/MAX8765/MAX8765A
Low-Cost Multichemistry Battery ChargersDCIN
LDO
MAX1908
MAX8724
MAX8765
MAX8765A
CLSREF
GND
CELLS
DLOV
AC ADAPTER INPUT
8.5V TO 28V
12.6V OUTPUT VOLTAGE
7.5A INPUT
CURRENT LIMIT
DHI
BST
SMART
BATTERY
HOSTACIN
59kΩ
19.6kΩ
1μF
VCTL
ICTL
REFIN
ACOK
ICHG
IINP
1MΩ
20kΩ
R10
10kΩ
C14
0.1μF
C20
0.1μF
CCV
C11
0.1μF
1kΩ
CCI
CCS
C10
0.01μF
0.01μF
C12
1μF
2 × 10μF
C13
1μF
C15
0.1μF
C16
1μF
LDO
R13
33Ω
CSSPCSSN
OPEN (3 CELLS SELECT)
RS1
0.01Ω
10μH
RS2
0.015Ω
CSIP
CSIN
PGND
DLON1b
N1a
BATT
22μF
BATT+
R19, R20, R21
10kΩ
AVDD/REF
SCL
SDA
TEMP
BATT-
ADC INPUT
ADC INPUT
OUTPUT
DAC OUTPUT
VCC
SCL
SDA
ADC INPUT
GND
PGNDGND
TO EXTERNAL
LOAD
SHDN
0.1μF0.1μF
Figure 1. µC-Controlled Typical Application Circuit
Typical Application CircuitsMAX1908/MAX8724/MAX8765/MAX8765A
