MAX1645BEEI-T ,Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current LimitingELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = +3.3V, V = +16.8V, V = +18V, T = 0°C to +85°C, ..
MAX1645EEI ,Advanced Chemistry-Independent / Level 2 Battery Chargers with Input Current LimitingELECTRICAL CHARACTERISTICS(Circuit of Figure 1, V = +3.3V, V = +16.8V, V = +18V, T = 0°C to +85°C, ..
MAX1647EAP ,Chemistry-Independent Battery ChargersApplicationsMAX1647EAP -40°C to +85°C 20 SSOPNotebook ComputersMAX1648ESE -40°C to +85°C 16 Narrow ..
MAX1647EAP ,Chemistry-Independent Battery ChargersFeaturesThe MAX1647/MAX1648 provide the power control neces-' Charges Any Battery Chemistry: sary ..
MAX1647EAP+ ,Chemistry-Independent Battery ChargersApplicationsMAX1647EAP -40°C to +85°C 20 SSOPNotebook ComputersMAX1648ESE -40°C to +85°C 16 Narrow ..
MAX1648ESE ,Chemistry-Independent Battery ChargersELECTRICAL CHARACTERISTICS(V = 18V, V = 4.096V, T = 0°C to +85°C. Typical values are at T = +25°C, ..
MAX4400AUK+T ,Single/Dual/Quad, Low-Cost, Single-Supply, Rail-to-Rail Op Amps with Shutdownapplications.● 1.4mA of Sink and Source Load CurrentThe MAX4400 single amplifier is available in ul ..
MAX4400AUK-T ,Single/Dual/Quad / Low-Cost / Single-Supply / Rail-to-Rail Op Amps with ShutdownELECTRICAL CHARACTERISTICS (continued)(V = +5V, V = 0, V = 0, V = V /2, R = ∞ connected to V /2, SH ..
MAX4400AXK+T ,Single/Dual/Quad, Low-Cost, Single-Supply, Rail-to-Rail Op Amps with ShutdownElectrical Characteristics (continued)(V = +5V, V = 0V, V = 0V, V = V /2, R = ∞ connected to V /2, ..
MAX4400AXK-T ,Single/Dual/Quad / Low-Cost / Single-Supply / Rail-to-Rail Op Amps with ShutdownELECTRICAL CHARACTERISTICS(V = +5V, V = 0, V = 0, V = V /2, R = ∞ connected to V /2, SHDN = V (MAX4 ..
MAX4400AXK-T ,Single/Dual/Quad / Low-Cost / Single-Supply / Rail-to-Rail Op Amps with ShutdownApplications*Future product—contact factory for availability.Single-Supply Zero-Crossing DetectorsI ..
MAX4401AXT ,Single/Dual/Quad, Low-Cost, Single-Supply, Rail-to-Rail Op Amps with ShutdownElectrical Characteristics(V = +5V, V = 0V, V = 0V, V = V /2, R = ∞ connected to V /2, SHDN = V (MA ..
MAX1645BEEI+-MAX1645BEEI-T
Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current Limiting
General DescriptionThe MAX1645B is a high-efficiency battery charger
capable of charging batteries of any chemistry type. It
uses the Intel System Management Bus (SMBus) to
control voltage and current-charge outputs.
When charging lithium-ion (Li+) batteries, the MAX1645B
automatically transitions from regulating current to regu-
lating voltage. The MAX1645B can also limit line input
current so as not to exceed a predetermined current
drawn from the DC source. A 175s charge safety timer
prevents “runaway charging” should the MAX1645B stop
receiving charging voltage/current commands.
The MAX1645B employs a next-generation synchro-
nous buck control circuitry that lowers the minimum
input-to-output voltage drop by allowing the duty cycle
to exceed 99%. The MAX1645B can easily charge one
to four series Li+ cells.
ApplicationsNotebook Computers
Point-of-Sale Terminals
Personal Digital Assistants
FeaturesInput Current Limiting175s Charge Safety Timeout128mA Wake-Up ChargeCharges Any Chemistry Battery: Li+, NiCd,
NiMH, Lead Acid, etc.Intel SMBus 2-Wire Serial InterfaceCompliant with Level 2 Smart Battery Charger
Spec Rev 1.0+8V to +28V Input Voltage RangeUp to 18.4V Battery Voltage11-Bit Battery Voltage Setting±0.8% Output Voltage Accuracy with Internal
Reference3A (max) Battery Charge Current6-Bit Charge-Current Setting 99.99% (max) Duty Cycle for Low-Dropout
OperationLoad/Source Switchover Drivers>97% Efficiency
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current LimitingCVS
PDS
CSSP
CSSN
BST
DHI
INT
DLOV
DLO
PGND
CSIP
CSIN
PDL
SDA
SCL
THM
VDD
DAC
BATT
GND
CCV
CCI
CCS
REF
CLS
LDO
DCIN
QSOPTOP VIEW
MAX1645B
PARTTEMP RANGEPIN-PACKAGEMAX1645BEEI-40°C to +125°C28 QSOP
19-2593; Rev 0; 10/02
Typical Operating Circuit appears at end of data sheet.SMBus is a trademark of Intel Corp.
Pin ConfigurationOrdering Information
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at= +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, CVS, CSSP, CSSN, LX to GND....................-0.3V to +30V
CSSP to CSSN, CSIP to CSIN...............................-0.3V to +0.3V
PDS, PDL to GND...................................-0.3V to (VCSSP+ 0.3V)
BST to LX..................................................................-0.3V to +6V
DHI to LX...................................................-0.3V to (VBST+ 0.3V)
CSIP, CSIN, BATT to GND.....................................-0.3V to +22V
LDO to GND.....................-0.3V to (lower of 6V or VDCIN+ 0.3V)
DLO to GND...........................................-0.3V to (VDLOV+ 0.3V)
REF, DAC, CCV, CCI, CCS, CLS to GND.....-0.3V to (VLDO+ 0.3V)
VDD, SCL, SDA, INT, DLOV to GND.........................-0.3V to +6V
THM to GND...............................................-0.3V to (VDD+ 0.3V)
PGND to GND.......................................................-0.3V to +0.3V
LDO Continuous Current.....................................................50mA
Continuous Power Dissipation (TA= +70°C)
28-Pin QSOP (derate 10.8mW/°C above +70°C).........860mW
Operating Temperature Range...........................-40°C to +85°C
Storage Temperature Range.............................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
GENERAL SPECIFICATIONSDCIN Typical Operating RangeVDCIN828V
DCIN Supply CurrentIDCIN8V < VDCIN < 28V1.76mA
DCIN Supply Current Charging
Inhibited8V < VDCIN < 28V0.72mA
DCIN rising7.57.85DCIN Undervoltage ThresholdWhen AC_PRESENT
switchesDCIN falling77.4V
LDO Output VoltageVLDO8V < VDCIN < 28V, 0 < ILDO < 15mA5.155.45.65V
VDD Input Voltage Range8V < VDCIN < 28V (Note 1)2.805.65V
VDD rising2.552.8VDD Undervoltage ThresholdWhen the S M Besp ond s to com m and sVDD falling2.12.5V
VDD Quiescent CurrentIDD0 < VDCIN < 6V, VDD = 5V, VSCL = 5V,
VSDA = 5V80150µA
REF Output VoltageVREF0 < IREF < 200µA4.0664.0964.126V
BATT Undervoltage ThresholdWhen ICHARGE drops to 128mA (Note 2)2.42.8V
PDS Charging Source Switch
Turn-Off ThresholdVPDS-OFFVCVS referred to VBATT, VCVS falling50100150mV
PDS Charging Source Switch
Threshold HysteresisVPDS-HYSVCVS referred to VBATT100200300mV
PDS Output Low Voltage, PDS
Below CSSPIPDS = 081012V
PDS Turn-On CurrentPDS = CSSP100150300µA
PDS Turn-Off CurrentVPDS = VCSSP - 2V, VDCIN = 16V1050mA
PDL Load Switch Turn-Off
ThresholdVPDL-OFFVCVS referred to VBATT, VCVS rising-150-100-50mV
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSPDL Load Switch Threshold
HysteresisVPDL-HYSVCVS referred to VBATT100200300mV
PDL Turn-Off CurrentVCSSN - VPDL = 1V612mA
PDL Turn-On ResistancePDL to GND50100150kΩ
CVS Input Bias CurrentVCVS = 28V620µA
ChargingVoltage() = 0x41A016.66616.816.934
ChargingVoltage() = 0x313012.49212.59212.692
ChargingVoltage() = 0x20D08.3338.48.467BATT Full-Charge VoltageV0
ChargingVoltage() = 0x10604.1504.1924.234
ChargingCurrent() =
0x0BC0139.9150.4160.9
BATT Charge Current-Sense
VoltageI0VCSIP - VCSIN
ChargingCurrent() =
0x00803.086.49.72
VCLS = 4.096V188.6204.8221.0DCIN Source Current-Limit
Sense VoltageVCSSP - VCSSNVCLS = 2.048V91.3102.4113.5mV
BATT Undervoltage Charge
Current-Sense VoltageVCSIP - VCSINVBATT = 1V3.086.49.72mV
Inductor Peak Current LimitVCSIP - VCSIN250300350mV
BATT/CSIP/CSIN Input Voltage
Range020V
Total BATT Input Bias CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V-700+700µA
Total BATT Quiescent CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V, charge inhibited-100+100µA
Total BATT Standby CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V, VDCIN = 0-5+5µA
CSSP Input Bias CurrentVCSSP = VCSSN = VDCIN = 0 to 28V-100540+1000µA
CSSN Input Bias CurrentVCSSP = CCSSN = VDCIN = 0 to 28V-10035+100µA
CSSP/CSSN Quiescent CurrentVCSSP = VCSSN = 28V, VDCIN = 0-1+1µA
Battery Voltage-Error Amp DC
GainFrom BATT to CCV200500V/V
CLS Input Bias CurrentVCLS = VREF/2 to VREF-1+0.05+1µA
Battery Voltage-Error Amp
Transconductance
From BATT to CCV, ChargingVoltage() =
0x41A0, VBATT = 16.8V0.1110.2220.444µA/mV
Battery Current-Error Amp
Transconductance
From CSIP/CSIN to CCI, ChargingCurrent()
= 0x0BC0, VCSIP - VCSIN = 150.4mV0.512.0µA/mV
Input Current-Error Amp
Transconductance
From CSSP/CSSN to CCS, VCLS = 2.048V,
VCSSP - VCSSN = 102.4mV0.512.0µA/mV
CCV/CCI/CCS Clamp VoltageVCCV = VCCI = VCCS = 0.25V to 2V (Note 3)150300600mV
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at= +25°C.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
DC-TO-DC CONVERTER SPECIFICATIONSMinimum Off-TimetOFF1.01.251.5µs
Maximum On-TimetON51015ms
Maximum Duty Cycle9999.99%
LX Input Bias CurrentVDCIN = 28V, VBATT = VLX = 20V200500µA
LX Input Quiescent CurrentVDCIN = 0, VBATT = VLX = 20V1µA
BST Supply CurrentDHI high615µA
DLOV Supply CurrentVDLOV = VLDO, DLO low510µA
DHI Output ResistanceDHI high or low, VBST - VLX = 4.5V614Ω
DLO Output ResistanceDLO high or low, VDLOV = 4.5V614Ω
THERMISTOR COMPARATOR SPECIFICATIONSTHM Input Bias CurrentVTHM = 4% of VDD to 96% of VDD, VDD =
2.8V to 5.65V-1+1µA
Thermistor Overrange ThresholdVDD = 2.8V to 5.65V, VTHM falling89.59192.5% of VDD
Thermistor Cold ThresholdVDD = 2.8V to 5.65V, VTHM falling7475.577% of VDD
Thermistor Hot ThresholdVDD = 2.8V to 5.65V, VTHM falling2223.525% of VDD
Thermistor Underrange
ThresholdVDD = 2.8V to 5.65V, VTHM falling67.59% of VDD
Thermistor Comparator
Threshold HysteresisAll four comparators, VDD = 2.8V to 5.65V1% of VDD
SMB INTERFACE LEVEL SPECIFICATIONS (VDD = 2.8V to 5.65V)SDA/SCL Input Low Voltage0.6V
SDA/SCL Input High Voltage1.4V
SDA/SCL Input Hysteresis220mV
SDA/SCL Input Bias Current-1+1µA
SDA Output Low Sink CurrentVSDA = 0.4V6mA
INT Output High LeakageV I NT = 5.65V1µA
INT Output Low VoltageI I NT = 1mA25200mV
SMB INTERFACE TIMING SPECIFICATIONS (VDD = 2.8V to 5.65V, Figures 4 and 5)SCL High PeriodtHIGH4µs
SCL Low PeriodtLOW4.7µs
Start Condition Setup Time
from SCLtSU:STA4.7µs
Start Condition Hold Time
from SCLtHD:STA4µs
SDA Setup Time from SCLtSU:DAT250ns
SDA Hold Time from SCLtHD:DAT0ns
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= 0°C to +85°C, unless otherwise noted. Typical values are at= +25°C.)
ELECTRICAL CHARACTERISTICS(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= -40°C to +85°C, unless otherwise noted. Guaranteed by design.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSDA Output Data Valid from SCLtDV1µs
Maximum Charge Period Without
a ChargingVoltage() or
Charging Current() Loaded
tWDT140175210s
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
GENERAL SPECIFICATIONSDCIN Typical Operating RangeVDCIN828V
DCIN Supply CurrentIDCIN8V < VDCIN < 28V6mA
DCIN Supply Current Charging
Inhibited8V < VDCIN < 28V2mA
DCIN rising7.85DCIN Undervoltage ThresholdWhen AC_PRESENT
switchesDCIN falling7V
LDO Output VoltageVLDO8V < VDCIN < 28V, 0 < ILDO < 15mA5.155.65V
VDD Input Voltage Range8V < VDCIN < 28V (Note 1)2.805.65V
VDD rising2.8VDD Undervoltage ThresholdWhen the S M Besp ond s to com m and sVDD falling2.1V
VDD Quiescent CurrentIDD0 < VDCIN < 6V, VDD = 5V, VSCL = 5V,
VSDA = 5V150µA
REF Output VoltageVREF0 < IREF < 200µA4.0354.157V
BATT Undervoltage ThresholdWhen ICHARGE drops to 128mA (Note 2)2.42.8V
PDS Charging Source Switch
Turn-Off ThresholdVPDS-OFFVCVS referred to VBATT, VCVS falling50150mV
PDS Charging Source Switch
Threshold HysteresisVPDS-HYSVCVS referred to VBATT100300mV
PDS Output Low Voltage, PDS
Below CSSPIPDS = 0812V
PDS Turn-On CurrentPDS = CSSP100300µA
PDS Turn-Off CurrentVPDS = VCSSP - 2V, VDCIN = 16V10mA
PDL Load Switch Turn-Off
ThresholdVPDL-OFFVCVS referred to VBATT, VCVS rising-150-50mV
PDL Load Switch Threshold
HysteresisVPDL-HYSVCVS referred to VBATT100300mV
PDL Turn-Off CurrentVCSSN - VPDL = 1V6mA
MAX1645B
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= -40°C to +85°C, unless otherwise noted. Guaranteed by design.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSPDL Turn-On ResistancePDL to GND50150kΩ
CVS Input Bias CurrentVCVS = 28V20µA
ERROR AMPLIFIER SPECIFICATIONSChargingVoltage() = 0x41A016.53217.068
ChargingVoltage() = 0x313012.39112.793
ChargingVoltage() = 0x20D08.2668.534BATT Full-Charge VoltageV0
ChargingVoltage() = 0x10604.1244.260
ChargingCurrent() =
0x0BC0130.4170.4
BATT Charge Current-Sense
VoltageI0VCSIP - VCSIN
ChargingCurrent() =
0x00800.7612.04
VCLS = 4.096V174.3235.3DCIN Source Current-Limit
Sense VoltageVCSSP - VCSSNVCLS = 2.048V82.2120.2mV
BATT Undervoltage Charge
Current-Sense VoltageVBATT = 1V, VCSIP - VCSIN110mV
Inductor Peak Current LimitVCSIP - VCSIN250350mV
BATT/CSIP/CSIN Input Voltage
Range020V
Total BATT Input Bias CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V-700+700µA
Total BATT Quiescent CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V, charge inhibited-100+100µA
Total BATT Standby CurrentTotal of IBATT, ICSIP, and ICSIN;
VBATT = 0 to 20V, VDCIN = 0-5+5µA
CSSP/Input Bias CurrentVCSSP = VCSSN = VDCIN = 0 to 28V-100+1000µA
CSSN Input Bias CurrentVCSSP = CCSSN = VDCIN = 0 to 28V-100+100mA
CSSP/CSSN Quiescent CurrentVCSSP = VCSSN = 28V, VDCIN = 0-1+1µA
Battery Voltage-Error Amp DC
GainFrom BATT to CCV200V/V
CLS Input Bias CurrentVCLS = VREF/2 to VREF-1+1µA
Battery Voltage-Error Amp
Transconductance
From BATT to CCV, ChargingVoltage() =
0x41A0, VBATT = 16.8V0.1110.444µA/mV
Battery Current-Error Amp
Transconductance
From CSIP/CSIN to CCI, ChargingCurrent()
= 0x0BC0, VCSIP - VCSIN = 150.4mV0.52.0µA/mV
Input Current-Error Amp
Transconductance
From CSSP/CSSN to CCS, VCLS = 2.048V,
VCSSP - VCSSN = 102.4mV0.52.0µA/mV
CCV/CCI/CCS Clamp VoltageVCCV = VCCI = VCCS = 0.25V to 2V (Note 3)150600mV
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= -40°C to +85°C, unless otherwise noted. Guaranteed by design.)
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITS
DC-TO-DC CONVERTER SPECIFICATIONSMinimum Off-TimetOFF1.01.5µs
Maximum On-TimetON515ms
Maximum Duty Cycle99%
LX Input Bias CurrentVDCIN = 28V, VBATT = VLX = 20V500µA
LX Input Quiescent CurrentVDCIN = 0, VBATT = VLX = 20V1µA
BST Supply CurrentDHI high15µA
DLOV Supply CurrentVDLOV = VLDO, DLO low10µA
DHI Output ResistanceDHI high or low, VBST - VLX = 4.5V14Ω
DLO Output ResistanceDLO high or low, VDLOV = 4.5V14Ω
THERMISTOR COMPARATOR SPECIFICATIONSTHM Input Bias CurrentVTHM = 4% of VDD to 96% of VDD,
VDD = 2.8V to 5.65V-1+1µA
Thermistor Overrange ThresholdVDD = 2.8V to 5.65V, VTHM falling89.592.5% of VDD
Thermistor Cold ThresholdVDD = 2.8V to 5.65V, VTHM falling7477% of VDD
Thermistor Hot ThresholdVDD = 2.8V to 5.65V, VTHM falling2225% of VDD
Thermistor Underrange
ThresholdVDD = 2.8V to 5.65V, VTHM falling69% of VDD
SMB INTERFACE LEVEL SPECIFICATIONS (VDD = 2.8V to 5.65V)SDA/SCL Input Low Voltage0.6V
SDA/SCL Input High Voltage1.4V
SDA/SCL Input Bias Current-1+1µA
SDA Output Low Sink CurrentVSDA = 0.4V6mA
INT Output High LeakageV I NT = 5.65V1µA
INT Output Low VoltageI I NT = 1mA200mV
SMB INTERFACE TIMING SPECIFICATIONS (VDD = 2.8V to 5.65V, Figures 4 and 5)SCL High PeriodtHIGH4µs
SCL Low PeriodtLOW4.7µs
Start Condition Setup Time
from SCLtSU:STA4.7µs
Start Condition Hold Time
from SCLtHD:STA4µs
SDA Setup Time from SCLtSU:DAT250ns
SDA Hold Time from SCLtHD:DAT0ns
REFERENCE VOLTAGE LOAD REGULATION
MAX1645B toc05
LOAD CURRENT (μA)
REF
(V)
LDO LOAD REGULATION
MAX1645B toc04
LOAD CURRENT (mA)
LDO
(V)
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Typical Operating Characteristics(Circuit of Figure 1, VDCIN= 20V, TA = +25°C, unless otherwise noted.)
BATTERY REMOVAL AND REINSERTION
TRANSIENT RESPONSEMAX1645B toc01
ChargingVoltage() = 16000mV
ChargingCurrent() = 1000mA
CCI
CCI
BATTERY REMOVEDBATTERY INSERTED
CCVCCV
CCICCV
16V
15V
1.25V
CCV
CCI
IBATT
BATT
0.75V
0.25V
2ms/div
LOAD-TRANSIENT RESPONSE
(STEP-IN LOAD CURRENT)MAX1645B toc02
ChargingCurrent() = 3.0A
0 TO 2A LOAD STEP, VBATT = 20V
ISOURCE LIMIT = 2.5A
CCS
CCSCCS
15.5V
15.0V
2.75V
2.25V
1.75V
0.75V
400μs/div
CCI
CCICCI
CCS
CCI
BATT
LDO LINE REGULATION
MAX1645B toc03
VDCIN (V)
LDO
(V)
ILOAD = 0
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX1645B toc06
TEMPERATURE (°C)
REF
(V)
ELECTRICAL CHARACTERISTICS (continued)(Circuit of Figure 1, VDD= +3.3V, VBATT= +16.8V, VDCIN= +18V, TA
= -40°C to +85°C, unless otherwise noted. Guaranteed by design.)
Note 1:Guaranteed by meeting the SMB timing specs.
Note 2:The charger reverts to a trickle-charge mode of ICHARGE= 128mA below this threshold.
Note 3:Voltage difference between CCV and CCI or CCS when one of these three pins is held low and the others try to pull high.
PARAMETERSYMBOLCONDITIONSMINTYPMAXUNITSSDA Output Data Valid from SCLtDV1µs
Maximum Charge Period Without
a ChargingVoltage() or
Charging Current() Loaded
tWDT140210s
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current LimitingEFFICIENCY vs. BATTERY CURRENT
(VOLTAGE-CONTROL LOOP)
MAX1645B toc07
BATTERY CURRENT (mA)
EFFICIENCY (%)
A: VDCIN = 20V, ChargingVoltage() = 16.8V
B: VDCIN = 16V, ChargingVoltage() = 8.4V
EFFICIENCY vs. BATTERY CURRENT
(CURRENT-CONTROL LOOP)
MAX1645B toc08
ChargingCurrent() (CODE)
EFFICIENCY (%)
A: VDCIN = 20V, VBATT = 16.8V
B: VDCIN = 16V, VBATT = 8.4V
OUTPUT VI CHARACTERISTICS
MAX1645B toc09
LOAD CURRENT (mA)
DROP IN BATT OUTPUT VOLTAGE (%)150020005001000250030003500
ChargingVoltage() = 16800mV
ChargingCurrent() = 3008mA
0.38000400012,00016,00020,000
BATT VOLTAGE ERROR
vs. ChargingVoltage() CODEMAX1645B toc10
ChargingVoltage() (CODE)
BATT VOLTAGE ERROR (%)
IBATT = 0
MEASURED AT AVAILABLE CODES10005001500200025003000
CURRENT-SETTING ERROR
vs. ChargingCurrent() CODEMAX1645B toc11
ChargingCurrent() (CODE)
BATT CURRENT ERROR (%)
VBATT = 12.6V
MEASURED AT AVAILABLE CODES
SOURCE/BATT CURRENT vs. LOAD CURRENT
WITH SOURCE CURRENT LIMIT
MAX1645B toc12
LOAD CURRENT (A)
SOURCE/BATT CURRENT (A)
IIN
IBATT
VCLS = 2V
RCSS = 40mΩ
VBATT = 16.8V
SOURCE CURRENT LIMIT = 2.5A
ChargingCurrent() = 3008mA
ChargingVoltage() = 18432mV
SOURCE/BATT CURRENT vs. VBATT
WITH SOURCE CURRENT LIMIT
MAX1645B toc13
VBATT (V)
SOURCE/BATT CURRENT (A)
IIN
IBATT
ILOAD = 2A
VCLS = 2V
RCSS = 40mΩ
ChargingVoltage() = 18432mV
ChargingCurrent() = 3008mA
SOURCE CURRENT LIMIT = 2.5A
Typical Operating Characteristics (continued)(Circuit of Figure 1, VDCIN= 20V, TA = +25°C, unless otherwise noted.)
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Pin Description
PINNAMEFUNCTIONDCINDC Supply Voltage InputLDO5.4V Linear-Regulator Voltage Output. Bypass with a 1µF capacitor to GND.CLSSource Current-Limit InputREF4.096V Reference Voltage OutputCCSCharging Source Compensation Capacitor Connection. Connect a 0.01µF capacitor from CCS to GND.CCIBattery Current-Loop Compensation Capacitor Connection. Connect a 0.01µF capacitor from CCI to GND.CCVBattery Voltage-Loop Compensation Capacitor Connection. Connect a 10kΩ resistor in series with a 0.01µF
capacitor to GND.GNDGroundBATTBattery Voltage OutputDACDAC Voltage OutputVDDLogic Circuitry Supply Voltage Input (2.8V to 5.65V)THMThermistor Voltage InputSCLSMB Clock InputSDASMB Data Input/Output. Open-drain output. Needs external pullup.INTInterrupt Output. Open-drain output. Needs external pullup.PDLPMOS Load Switch Driver OutputCSINBattery Current-Sense Negative InputCSIPBattery Current-Sense Positive InputPGNDPower GroundDLOLow-Side NMOS Driver OutputDLOVLow-Side NMOS Driver Supply Voltage. Bypass with 0.1µF capacitor to GND.LXInductor Voltage Sense InputDHIHigh-Side NMOS Driver OutputBSTHigh-Side Driver Bootstrap Voltage Input. Bypass with 0.1µF capacitor to LX.CSSNCharging Source Current-Sense Negative InputCSSPCharging Source Current-Sense Positive InputPDSCharging Source PMOS Switch Driver OutputCVSCharging Source Voltage Input
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Detailed DescriptionThe MAX1645B consists of current-sense amplifiers, an
SMBus interface, transconductance amplifiers, reference
circuitry, and a DC-DC converter (Figure 2). The DC-DC
converter generates the control signals for the external
MOSFETs to maintain the voltage and the current set by
the SMBus interface. The MAX1645B features a voltage-
regulation loop and two current-regulation loops. The
loops operate independently of each other. The voltage-
regulation loop monitors BATT to ensure that its voltage
never exceeds the voltage set point (V0). The battery cur-
rent-regulation loop monitors current delivered to BATT to
ensure that it never exceeds the current-limit set point
(I0). The battery current-regulation loop is in control as
long as BATT voltage is below V0. When BATT voltage
reaches V0, the current loop no longer regulates. A third
loop reduces the battery-charging current when the sum
of the system (the main load) and the battery charger
input current exceeds the charging source current limit.
Setting Output VoltageThe MAX1645B voltage DAC has a 16mV LSB and an
18.432V full scale. The SMBus specification allows for a
16-bit ChargingVoltage() command that translates to a
1mV LSB and a 65.535V full-scale voltage; therefore,
the ChargingVoltage() value corresponds to the output
voltage in millivolts. The MAX1645B ignores the first 4
LSBs and uses the next 11 LSBs to control the voltage
DAC. All codes greater than or equal to 0x4800
(18432mV) result in a voltage overrange, limiting the
charger voltage to 18.432V. All codes below 0x0400
(1024mV) terminate charging.
Setting the Charge CurrentThe MAX1645B charge-current DAC has a 3.2mV to
150.4mV range. The SMBus specification allows for a
16-bit ChargingCurrent() command that translates to a
0.05mV LSB and a 3.376V full-scale current-sense volt-
age. The MAX1645B drops the first 6 LSBs and uses
the remaining 6 MSBs to control the charge-current
DAC. All codes above 0x0BC0 result in an overrange
condition, limiting the charge current-sense voltage to
150.4mV. All codes below 0x0080 turn off the charging
current. Therefore, the charging current (ICHARGE) is
determined by:
ICHARGE= VDACI/ RCSI
where VDACIis the current-sense voltage set by
ChargingCurrent(), and RCSIis the battery current-
sense resistor (R2 in Figure 1). When using a 50mΩ
current-sense resistor, the ChargingCurrent() value cor-
responds directly to the charging current in milliamps
(0x0400 = 1024mA = 52.2mV/50mΩ).
Input Current LimitingThe MAX1645B limits the current drawn by the charger
when the load current becomes high. The device limits
the charging current so the AC adapter voltage is not
loaded down. An internal amplifier, CSS, compares the
voltage between CSSP and CSSN to the voltage at
CLS/20. VCLSis set by a resistor-divider between REF
and GND.
The input source current is the sum of the device cur-
rent, the charge input current, and the load current. The
device current is minimal (6mA max) in comparison to
the charge and load currents. The charger input cur-
rent is generated by the DC-DC converter; therefore, the
actualsource current required is determined as follows:
ISOURCE= ILOAD+ [(ICHARGE✕VBATT)/ (VIN✕η)]
where ηis the efficiency of the DC-DC converter (typi-
cally 85% to 95%).
VCLSdetermines the threshold voltage of the CSS com-
parator. R3 and R4 (Figure 1) set the voltage at CLS.
Sense resistor R1 sets the maximum allowable source
current. Calculate the maximum current as follows:
IMAX= VCLS/ (20 ✕R1)
(Limit VCSSP - VCSSNto between 102.4mV and
204.8mV.)
The configuration in Figure 1 provides an input current
limit of:
IMAX= (2.048V / 20) / 0.04Ω= 2.56A
LDO RegulatorAn integrated LDO regulator provides a +5.4V supply
derived from DCIN, which can deliver up to 15mA of
current. The LDO sets the gate-drive level of the NMOS
switches in the DC-DC converter. The drivers are actu-
ally powered by DLOV and BST, which must be con-
nected to LDO through a lowpass filter and a diode as
shown in Figure 1. Also see the MOSFET Driverssec-
tion. The LDO also supplies the 4.096V reference and
most of the control circuitry. Bypass LDO with a 1µF
capacitor.
VDDSupplyThis input provides power to the SMBus interface and
the thermistor comparators. Typically connect VDDto
LDO or, to keep the SMBus interface of the MAX1645B
active while the supply to DCIN is removed, connect an
external supply to VDD.
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current LimitingLOAD
ADAPTER IN
MAX1645B
CVS
DCIN
REF
CLS
GND
DAC
CCV
CCI
CCS
PDS
CSSP
CSSN
LDO
DHI
DLOV
BST
PGND
DLO
CSIP
CSIN
PDL
BATT
THM
VDD
SCL
SDA
INT
BATTERY
HOST
1N4148
1μF
R13
1kΩ
C23
0.1μF
1μF
100kΩ
100kΩ
0.1μF
0.01μF
FDS6675D1
1N5821
22μF
22μFR1
0.04Ω
C20, 1μF
C19, 1μF
R14
4.7Ω
R15
4.7Ω
1μFD3
CMPSH3
R12
33Ω
C16
0.22μF
C14
0.1μFN1
FDS6680
FDS6612A
22μHD2
1N5821
10kΩ
C12
1μFR8
10kΩ
10kΩ
R10
10kΩ
C13
1.5nF
10kΩ
0.05Ω
FDS6675C4
22μF
22μF
C18
0.1μF
R16
R11
C24
0.1μF
10kΩ
R17
10kΩ
R18
10kΩ
C11
1nF
C10
1nF
Figure 1. Typical Application Circuit
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current LimitingLVC
GMS
PDS
REF
PDL
CSS
CSSP
CSSN
CLS
CSIP
CSIN
VDD
SCL
SDA
THM
CSI
BATT
GMI
GMV
SMB
DACI
DACV
TEMP
DC-DC
DHI
BST
DHI
DLOV
DLO
PGND
CCS
CCI
CCV
CVS
BATT
PDS
PDL
DCIN
LDO
REF
GND
DAC
DLO
MAX1645B
INT
Figure 2. Functional Diagram
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Operating ConditionsThe MAX1645B changes its operation depending on
the voltages at DCIN, BATT, VDD,and THM. Several
important operating states follow:
AC Present.When DCIN is >7.5V, the battery is con-
sidered to be in an AC present state. In this condi-
tion, both the LDO and REF function properly and
battery charging is allowed. When AC is present, the
AC_PRESENT bit (bit 15) in the ChargerStatus() reg-
ister is set to 1.
Power Fail.When DCIN is
in the power-fail state, since the charger does not
have enough input voltage to charge the battery. In
power fail, the PDS input PMOS switch is turned off
and the POWER_FAIL bit (bit 13) in the
ChargerStatus() register is set to 1.Battery Present.When THM is <91% of VDD, the
battery is considered to be present. The MAX1645B
uses the THM pin to detect when a battery is con-
nected to the charger. When the battery is present,
the BATTERY_PRESENT bit (bit 14) in the
ChargerStatus() register is set to 1 and charging can
proceed. When the battery is not present, all of the
registers are reset. With no battery present, the
charger performs a “float” charge to minimize con-
tact arcing on battery connection. The “float” charge
still tries to regulate the BATT pin voltage at 18.32V
with 128mA of current compliance.Battery Undervoltage.When BATT <2.5V, the bat-
tery is in an undervoltage state. This causes the
charger to reduce its current compliance to 128mA.
The content of the ChargingCurrent() register is unaf-
fected and, when the BATT voltage exceeds 2.7V,
normal charging resumes. ChargingVoltage() is unaf-
fected and can be set as low as 1.024V.VDDUndervoltage.When VDD<2.5V, the VDDsup-
ply is in an undervoltage state, and the SMBus inter-
face does not respond to commands. Coming out of
the undervoltage condition, the part is in its Power-
On Reset state. No charging occurs when VDDis
under voltage.
SMBus Interface
The MAX1645B receives control inputs from the SMBus
interface. The serial interface complies with the SMBus
specification (refer to the System Management Bus
Specification from Intel Corporation). Charger function-
ality complies with the Intel/Duracell Smart Charger
Specification for a Level 2 charger.
The MAX1645B uses the SMBus read-word and write-
word protocols to communicate with the battery being
charged, as well as with any host system that monitors
the battery-to-charger communications as a Level 2
SMBus charger. The MAX1645B is an SMBus slave
device and does not initiate communication on the bus.
It receives commands and responds to queries for sta-
tus information. Figure 3 shows examples of the SMBus
write-word and read-word protocols, and Figures 4 and
5 show the SMBus serial-interface timing.
Each communication with this part begins with the
MASTER issuing a START condition that is defined as a
falling edge on SDA with SCL high and ends with a
STOP condition defined as a rising edge on SDA with
SCL high. Between the START and STOP conditions,
the device address, the command byte, and the data
bytes are sent. The MAX1645B’s device address is
0x12 and supports the charger commands as
described in Tables 1–6.
Battery Charger Commands
ChargerSpecInfo()
The ChargerSpecInfo() command uses the read-word
protocol (Figure 3b). The command code for
ChargerSpecInfo() is 0x11 (0b00010001). Table 1 lists
the functions of the data bits (D0–D15). Bit 0 refers to the
D0 bit in the read-word protocol. The MAX1645B com-
plies with Level 2 Smart Battery Charger Specification
Revision 1.0; therefore, the ChargerSpecInfo() command
returns 0x09.
ChargerMode()
The ChargerMode() command uses the write-word
protocol (Figure 3a). The command code for
ChargerMode() is 0x12 (0b00010010). Table 2 lists the
functions of the data bits (D0–D15). Bit 0 refers to the
D0 bit in the write-word protocol.
To charge a battery that has a thermistor impedance in
the HOT range (i.e., THERMISTOR_HOT = 1 and
THERMISTOR_UR = 0), the host must use the
ChargerMode() command to clear HOT_STOP after the
battery is inserted. The HOT_STOP bit returns to its
default power-up condition (1) whenever the battery is
removed.
ChargerStatus()
The ChargerStatus() command uses the read-word
protocol (Figure 3b). The command code for
ChargerStatus() is 0x13 (0b00010011). Table 3
describes the functions of the data bits (D0–D15). Bit 0
refers to the D0 bit in the read-word protocol.
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
Figure 3. SMBus Write-Word and Read-Word Protocols
Preset to
0b0001001
D7 D0D15 D8ChargerMode() = 0x12
ChargingCurrent() = 0x14
ChargerVoltage() = 0x15
AlarmWarning() = 0x16
Preset to
0b0001001
Preset to
0b0001001
D7 D0D15 D8ChargerSpecInfo() =
0x11
ChargerStatus() =
0x13
ACKMSB LSB8 bits
ACKCOMMAND
BYTEMSB LSB7 bitsSLAVE
ADDRESSSMSB LSB8 bits
ACK
LOW
DATA
BYTEMSB LSB8 bits
ACK
HIGH
DATA
BYTEWrite-Word Format
b) Read-Word Format
Legend:
S = Start Condition or Repeated Start ConditionP = Stop Condition
ACK = Acknowledge (logic low)NACK = NOTAcknowledge (logic high)= Write Bit (logic low)R = Read Bit (logic high)
MASTER TO SLAVE
SLAVE TO MASTER
HIGH
DATA
BYTE
NACK
8 bits1b
MSB LSB1
LOW
DATA
BYTE
ACK
8 bits1b
MSB LSB0
SLAVE
ADDRESSR
7 bits1b
MSB LSB1
ACK
COMMAND
BYTEACK
8 bits1b
MSB LSB0ACKSLAVE
ADDRESSW
7 bits1b
MSB LSB0
The ChargerStatus() command returns information
about thermistor impedance and the MAX1645B’s inter-
nal state. The latched bits, THERMISTOR_HOT and
ALARM_INHIBITED, are cleared whenever BATTERY_
PRESENT = 0 or ChargerMode() is written with
POR_RESET = 1. The ALARM_INHIBITED status bit can
also be cleared by writing a new charging current OR
charging voltage.
MAX1645B
Advanced Chemistry-Independent, Level 2
Battery Charger with Input Current Limiting
START
CONDITION
MOST SIGNIFICANT
ADDRESS BIT (A6)
CLOCKED INTO SLAVE
A5 CLOCKED
INTO SLAVE
A4 CLOCKED
INTO SLAVE
A3 CLOCKED
INTO SLAVE
tHIGHtLOWtHD:STA
tSU:STAtSU:DATtHD:DAT
SCL
SDA
tSU:DATtHD:DAT
tDV
SLAVE PULLING
SDA LOW
tDV
MOST SIGNIFICANT BIT
OF DATA CLOCKED
INTO MASTER
ACKNOWLEDGE
BIT CLOCKED
INTO MASTER
R/W BIT
CLOCKED
INTO SLAVE
SCL
SDA
Figure 4. SMBus Serial Interface Timing—Address
Figure 5. SMBus Serial Interface Timing—Acknowledgment
