MAX1645AEEI-T ,Advanced-Chemistry-Independent, Level-2 Battery Chargers with Input Current LimitingApplications♦ 3A max Battery Charge CurrentNotebook Computers♦ 6-Bit Charge Current Setting Point-o ..
MAX1645BEEI ,Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current LimitingFeaturesThe MAX1645B is a high-efficiency battery charger Input Current Limitingcapable of chargin ..
MAX1645BEEI ,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, ..
MAX1645BEEI ,Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current LimitingApplications 3A (max) Battery Charge CurrentNotebook Computers 6-Bit Charge-Current Setting Point ..
MAX1645BEEI+ ,Advanced Chemistry-Independent, Level 2 Battery Charger with Input Current LimitingApplications♦ 3A (max) Battery Charge CurrentNotebook Computers♦ 6-Bit Charge-Current Setting Point ..
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, ..
MAX4397SCTM ,Audio/Video Switch For Dual SCART ConnectorsFeaturesThe MAX4397 dual SCART switch matrix routes audio♦ Video Outputs Drive 2V into 150ΩP-P and ..
MAX4397SCTM+ ,Audio/Video Switch for Dual SCART ConnectorsFeaturesThe MAX4397 dual SCART switch matrix routes audio♦ Video Outputs Drive 2V into 150ΩP-P and ..
MAX4399CTK ,Audio/Video Switch for Three SCART ConnectorsApplicationsCVBS RGBSTBENCODERSatellite ReceiversTV SCARTR/L AUDIO R/L AUDIO CONNECTORSatellite Set ..
MAX4399CTK+ ,Audio/Video Switch for Three SCART ConnectorsApplicationsRGBCVBSSTBENCODERSatellite ReceiversTV SCARTR/L AUDIOR/L AUDIO CONNECTORSatellite Set-T ..
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 ..
MAX1645AEEI-T
Advanced-Chemistry-Independent, Level-2 Battery Chargers with Input Current Limiting
General DescriptionThe MAX1645 are high-efficiency battery chargers capa-
ble of charging batteries of any chemistry type. It uses the
Intel System Management Bus (SMBus) to control volt-
age and current charge outputs.
When charging lithium-ion (Li+) batteries, the MAX1645
automatically transition from regulating current to regu-
lating voltage. The MAX1645 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 MAX1645 stop
receiving charging voltage/ current commands.
The MAX1645 employs a next-generation synchronous
buck control circuity that lowers the minimum input-to-
output voltage drop by allowing the duty cycle to
exceed 99%. The MAX1645 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
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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
MAX1645
MAX1645A
19-1566; Rev 2; 1/01
PART
MAX1645EEI-40°C to +85°C
TEMP. RANGEPIN-PACKAGE28 QSOP
Typical Operating Circuit appears at end of data sheet.SMBus is a trademark of Intel Corp.
Pin ConfigurationOrdering Information
MAX1645AEEI-40°C to +85°C28 QSOP
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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.........................................-60°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
8V < VDCIN< 28V
VCVSreferred to VBATT, VCVSrising
VPDS= VCSSP- 2V, VDCIN= 16V
PDS = CSSP
IPDS= 0
0 < VDCIN< 6V, VDD= 5V, VSCL= 5V,
VSDA= 5V
VCVSreferred to VBATT
VCVSreferred to VBATT, VCVSfalling
When the SMB res-
ponds to commands
8V < VDCIN< 28V
8V < VDCIN< 28V
When AC_PRESENT
switches
When ICHARGEdrops to 128mA
8V < VDCIN< 28V, 0 < ILDO< 15mA
0 < IREF< 200µA
CONDITIONS-150-100-50VPDL-OFFPDL Load Switch Turn-Off
Threshold1050PDS Turn-Off Current100150300PDS Turn-On Current81012PDS Output Low Voltage, PDS
Below CSSP100200300VPDS-HYSPDS Charging Source Switch
Threshold Hysteresis50100150VPDS-OFFPDS Charging Source Switch
Turn-Off Threshold2.42.8BATT Undervoltage Threshold
(Note 2)4.0664.0964.126VREFREF Output Voltage1.76IDCINDCIN Supply Current828VDCIN80150IDDVDDQuiescent Current
2.12.5V2.552.8VDDUndervoltage Threshold2.85.65VDDInput Voltage Range
(Note 1)0.72DCIN Supply Current Charging
Inhibited7.57.85DCIN Undervoltage Threshold77.45.155.45.65VLDOLDO Output Voltage
UNITSMINTYPMAXSYMBOLPARAMETERDCIN rising
DCIN falling
VDDrising
VDDfalling
DCIN Typical Operating Range
GENERAL SPECIFICATIONS
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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.)
CCV/CCI/CCS Clamp Voltage
(Note 4)VCCV= VCCI= VCCS= 0.25V to 2V 150300600mV
61.6128194.4VBATT= 1V,
RCSI= 50mΩ
VBATT= 1V,
RCSI= 50mΩ
MAX1645A
CSSN Input Bias Current-10035100mAVCSSP = CCSSN = VDCIN= 0 to 28V
VCLS= 2.048V
VCLS= 4.096V
ChargingCurrent() =
0x0080
ChargingCurrent() =
0x0BC0
DCIN Source Current Limit
(Note 3)
CLS Input Bias Current-10.051µA
Battery Voltage-Error Amp
Transconductance0.1110.2220.444µA/mV
Battery Current-Error Amp
Transconductance0.512µA/mV
Input Current-Error Amp
Transconductance0.512
PARAMETERSYMBOLMINTYPMAXUNITS12.49212.59212.692VBATT Full-Charge VoltageV0
CVS Input Bias Current620µA
BATT Charge Current (Note 3)I0
2.7983.0083.218A
61.6128194.4mA
4.7145.125.526A
PDL Turn-Off Current
PDL Load Switch Threshold
HysteresisVPDL-HYS100200300mV
612mA
PDL Turn-On Resistance50100150kΩ
BATT Undervoltage Charge
Current128200
BATT/CSIP/CSIN Input Voltage
Range020V
Total BATT Input Bias Current-700700µA
Total BATT Quiescent Current-100100µA
Total BATT Standby Current-55µA
CSSP Input Bias Current-1005401000µA
CSSP/CSSN Quiescent Current-11µA
Battery Voltage-Error Amp DC
Gain200500V/V
µA/mV
VCLS= VREF/2 to VREF
From BATT to CCV, ChargingVoltage() =
0x41A0, VBATT= 16.8V
From CSIP/SCIN to CCI, ChargingCurrent() =
0x0BC0, VCSIP- VCSIN= 150.4mV
CONDITIONSChargingVoltage() = 0x20D0
MAX1645
ChargingVoltage() = 0x3130
ChargingVoltage() = 0x41A0
VCVS= 28V
ChargingVoltage() = 0x1060
RCS = 50mΩ
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V
RCSS= 40mΩ
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V, charge inhibited
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V, VDCIN= 0
VCSSP = VCSSN = VDCIN= 0 to 28V
VCVSreferred to VBATT
VCSSP = VCSSN= 28V, VDCIN= 0
VCSSN- VPDL= 1V
From BATT to CCV
From CSSP/CSSN to CCS, VCLS= 2.048V,
VCSSP- VCSSN= 102.4mV
PDL to GND
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current LimitingVSDA= 0.4V
All 4 comparators, VDD= 2.8V to 5.65V
VDD= 2.8V to 5.65V, VTHMfalling
VDD= 2.8V to 5.65V, VTHMfalling
DLO high or low, VDLOV= 4.5V
DHI high or low, VBST- VLX= 4.5V
VDD= 2.8V to 5.65V, VTHMfalling
VDD= 2.8V to 5.65V, VTHM falling
RCSI= 50mΩ
VDLOV= VLDO, DLO low
VDCIN= 28V, VBATT= VLX= 20V
VDCIN= 0, VBATT= VLX= 20V
VTHM= 4% of VDDto 96% of VDD,
VDD= 2.8V to 5.65V
DHI high
CONDITIONS6SDA Output Low Sink Current-11SDA/SCL Input Bias Current220SDA/SCL Input Hysteresis1.4SDA/SCL Input High Voltage0.6SDA/SCL Input Low VoltageThermistor Comparator
Threshold Hysteresis7.59Thermistor Underrange
Threshold
% of VDD23.525Thermistor Hot Threshold 75.577Thermistor Cold Threshold
89.59192.5Thermistor Overrange Threshold -11THM Input Bias Current51015tONMaximum On-Time11.251.5tOFFMinimum Off-Time614DLO Output Resistance6 14DHI Output Resistance5.06.07.0Inductor Peak Current Limit5 10DLOV Supply Current9999.99Maximum Duty Cycle200500LX Input Bias Current1LX Input Quiescent Current615BST Supply Current
UNITSMINTYPMAXSYMBOLPARAMETERIINT= 1mA
VINT= 5.65V252001INTOutput High Leakage
INTOutput Low Voltage0tHD:DATSDA Hold Time from SCL250tSU:DATSDA Setup Time from SCL4tHIGHSCL High Period4.7tLOWSCL Low Period4.7tSU:STAStart Condition Setup Time
from SCL4tHD:STAStart Condition Hold Time
from SCL
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.)
% of VDD
% of VDD
% of VDD
% of VDD
DC-TO-DC CONVERTER SPECIFICATIONS
THERMISTOR COMPARATOR SPECIFICATIONS
SMB INTERFACE LEVEL SPECIFICATIONS(VDD= 2.8V to 5.65V)
SMB INTERFACE TIMING SPECIFICATIONS(VDD= 2.8V to 5.65V, Figures 4 and 5)
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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.)
CONDITIONSUNITSMINTYPMAXSYMBOLPARAMETER140175210tWDT
Maximum Charge Period
Without a ChargingVoltage() or
Charging Current() Loaded1tDVSDA Output Data Valid from SCL
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.)
PARAMETERSYMBOLMINMAXUNITSLDO Output VoltageVLDO5.155.65VDCIN Undervoltage Threshold 7.85V
DCIN Supply Current Charging
Inhibited2mA
VDDInput Voltage Range
(Note 1)2.85.65V
VDDUndervoltage Threshold2.8V2.1
VDDQuiescent CurrentIDD150µA
DCIN Typical Operating Range VDCIN828V
DCIN Supply CurrentIDCIN6mA
REF Output VoltageVREF4.0354.157V
BATT Undervoltage Threshold
(Note 2)2.42.8V
PDS Charging Source Switch
Turn-Off ThresholdVPDS-OFF50150mV
PDS Charging Source Switch
Threshold HysteresisVPDS-HYS100300mV
PDS Output Low Voltage, PDS
Below CSSP812V
PDS Turn-On Current100300µA
PDS Turn-Off Current10mA
PDL Load Switch Turn-Off
ThresholdVPDL-OFF-150-50mV
PDL Load Switch Threshold
HysteresisVPDL-HYS100300mV
PDL Turn-Off Current6mA
CONDITIONS0 < IREF< 200µA
8V < VDCIN< 28V, 0 < ILDO< 15mA
When ICHARGEdrops to 128mA
When AC_PRESENT
switches
8V < VDCIN< 28V
8V < VDCIN< 28V
When the SMB res-
ponds to commands
VCVSreferred to VBATT, VCVSfalling
VCVSreferred to VBATT
0 < VDCIN< 6V, VDD= 5V, VSCL= 5V,
VSDA= 5V
IPDS= 0
PDS = CSSP
VPDS= VCSSP- 2V, VDCIN= 16V
VCVSreferred to VBATT, VCVSrising
VCVSreferred to VBATT
VCSSN- VPDL= 1V
8V < VDCIN< 28V
DCIN rising
DCIN falling
VDDrising
VDDfalling
GENERAL SPECIFICATIONS
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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.)Maximum Duty Cycle99%
Minimum Off-TimetOFF11.5µs
Maximum On-TimetON515ms
PARAMETERSYMBOLMINMAXUNITS12.39112.793BATT Full-Charge VoltageV0
BATT Charge Current (Note 3)I0
2.6083.408A
15.2240.8mA
DCIN Source Current Limit
(Note 3)
4.3585.882A2.0543.006
CVS Input Bias Current
PDL Turn-On Resistance50150kΩµA
BATT Undervoltage Charge
Current20200mA
BATT/CSIP/CSIN Input Voltage
Range020V
Total BATT Input Bias Current-700700µA
Total BATT Quiescent Current-100100µA
Total BATT Standby Current-55µA
CSSP/Input Bias Current-1001000µA
CSSP/CSSN Quiescent Current-11µA
Battery Voltage-Error Amp DC
Gain200V/V
CLS Input Bias Current-11µA
Battery Voltage-Error Amp
Transconductance0.1110.444µA/mV
Battery Current-Error Amp
Transconductance0.52µA/mV
Input Current-Error Amp
Transconductance0.52µA/mV
CCV/CCI/CCS Clamp Voltage
(Note 4)150600mV
CONDITIONSVBATT= 1V, RCSI= 50mΩ
ChargingVoltage() = 0x1060
ChargingVoltage() = 0x20D0
ChargingVoltage() = 0x3130
ChargingVoltage() = 0x41A0
RCSI= 50mΩ
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V, charge inhibited
RCSS= 40mΩ
Total of IBATT, ICSIP,and ICSIN;
VBATT= 0 to 20V, VDCIN= 0
VCSSP= VCSSN= VDCIN= 28V
VCSSP= VCSSN= 28V, VDCIN= 0
PDL to GND
From BATT to CCV
VCVS= 28V
VCLS= VREF/2 to VREF
From BATT to CCV, ChargingVoltage() =
0x41A0, VBATT= 16.8V
From CSIP/CSIN to CCI, ChargingCurrent() =
0x0BC0, VCSIP-VCSIN= 150.4mV
From CSSP/CSSN to CCS, VCLS= 2.048V,
VCSSP- VCSSN= 102.4mV
VCCV= VCCI= VCCS = 0.25V to 2V
ChargingCurrent() =
0x0BC0
ChargingCurrent() =
0x0080
VCLS= 4.096V
VCLS= 2.048V
CSSN Input Bias Current-100100µAVCSSP= VCSSN= VDCIN= 28V
DC-TO-DC CONVERTER SPECIFICATIONS
ERROR AMPLIFIER SPECIFICATIONS
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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.)SDA Hold Time from SCLtHD:DAT0ns
Start Condition Hold Time
from SCL
Start Condition Setup Time
from SCLtSU:STA4.7µs
tHD:STA4µs
SDA Setup Time from SCLtSU:DAT250ns
PARAMETERSYMBOLMINMAXUNITSDLO Output Resistance14Ω
DHI Output Resistance14Ω
Inductor Peak Current Limit5.07.0A
DLOV Supply Current10µA
THM Input Bias Current-11µA
Thermistor Overrange Threshold 89.592.5
Thermistor Cold Threshold 7477
LX Input Quiescent Current
LX Input Bias Current500µAµA
BST Supply Current15µA
Thermistor Hot Threshold 2225
% of VDD
Thermistor Underrange
Threshold 69
SDA/SCL Input Low Voltage0.6V
SDA/SCL Input High Voltage1.4V
SDA/SCL Input Bias Current-11µA
SDA Output Low Sink Current6mA
INTOutput High Leakage1µA
INTOutput Low Voltage200mV
SCL High PeriodtHIGH4µs
SCL Low PeriodtLOW4.7µs
CONDITIONSVDD= 2.8V to 5.65V, VTHMfalling
DLO high or low, VDLOV= 4.5V
VDD= 2.8V to 5.65V, VTHMfalling
DHI high or low, VBST- VLX= 4.5V
RCSI= 50mΩ
VDLOV= VLDO, DLO low
VTHM= 4% of VDDto 96% of VDD,
VDD= 2.8V to 5.65V
VDD= 2.8V to 5.65V, VTHMfalling
VDD= 2.8V to 5.65V, VTHMfalling
VDCIN= 28V, VBATT= VLX= 20V
VSDA= 0.4V
VDCIN= 0, VBATT= VLX= 20V
VINT= 5.65V
IINT= 1mA
DHI high
% of VDD
% of VDD
% of VDD
SMB INTERFACE LEVEL SPECIFICATIONS(VDD= 2.8V to 5.65V)
THERMISTOR COMPARATOR SPECIFICATIONS
SMB INTERFACE TIMING SPECIFICATIONS(VDD= 2.8V to 5.65V, Figures 4 and 5)
REFERENCE VOLTAGE LOAD REGULATION
MAX1645 toc05
LOAD CURRENT (μA)
REF
(V)
LDO LOAD REGULATION
MAX1645 toc04
LOAD CURRENT (mA)
LDO
(V)
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
Typical Operating Characteristics(Circuit of Figure 1, VDCIN= 20V, TA = +25°C, unless otherwise noted.)
LOAD-TRANSIENT RESPONSE
(BATTERY REMOVAL AND REINSERTION)MAX1645 toc01
ChargingVoltage() = 15000mV
ChargingCurrent() = 1000mA
CCICCI
CCI
16V
14V
12V
1.5V
CCV
CCI
IBATT
BATT
0.5V
2ms/div
CCV
CCVCCV
BATTERY REMOVEDBATTERY INSERTED
LOAD-TRANSIENT RESPONSE
(STEP IN LOAD CURRENT)MAX1645 toc02
ChargingCurrent() = 3008mA
VBATT = 16V
LOAD STEP: 0A TO 2A
ISOURCE LIMIT = 2.5A
CCSCCS
CCS
1ms/div
CCICCICCI
CCV
CCI
IBATT
BATT
LDO LINE REGULATION
MAX1645 toc03
VDCIN (V)
LDO
(V)
ILOAD = 0
REFERENCE VOLTAGE
vs. TEMPERATURE
MAX1645 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:Does not include current-sense resistor tolerance.
Note 4:Voltage difference between CCV, and CCI or CCS when one of these three pins is held low and the others try to pull high.
Maximum Charge Period
Without a ChargingVoltage() or
Charging Current() loaded
tWDT140210s
SDA Output Data Valid
from SCLtDV1µs
PARAMETERSYMBOLMINMAXUNITSCONDITIONS
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current LimitingEFFICIENCY vs. BATTERY CURRENT
(VOLTAGE-CONTROL LOOP)
MAX1645 toc07
BATTERY CURRENT (mA)
EFFICIENCY (%)
A: VDCIN = 20V, ChargingVoltage() = 16.8V
B: VDCIN = 16V, ChargingVoltage() = 8.4V
EFFICIENCY vs. BATTERY CURRENT
(CURRENT-CONTROL LOOP)
MAX1645 toc08
ChargingCurrent() (CODE)
EFFICIENCY (%)
A: VDCIN = 20V, VBATT = 16.8V
B: VDCIN = 16V, VBATT = 8.4V
OUTPUT VI CHARACTERISTICS
MAX1645 toc09
LOAD CURRENT (mA)
DROP IN BATT OUTPUT VOLTAGE (%)150020005001000250030003500
ChargingVoltage() = 16,800mV
ChargingCurrent() = 3008mA
BATT VOLTAGE ERROR
vs. ChargingVoltage() CODE
MAX1645 toc10
ChargingVoltage() (CODE)
BATT VOLTAGE ERROR (%)
IBATT = 0
MEASURED AT AVAILABLE CODES10005001500200025003000
CURRENT-SETTING ERROR
vs. ChargingCurrent() CODEMAX1645 toc11
ChargingCurrent() (CODE)
BATT CURRENT ERROR (%)
VBATT = 12.6V
MEASURED AT AVAILABLE CODES
SOURCE/BATT CURRENT vs. LOAD CURRENT
WITH SOURCE CURRENT LIMIT
MAX1645 toc12
SOURCE/BATT CURRENT (A)
IIN
IBATT
VCLS = 2V
RCSS = 40mΩ
VBATT = 16.8V
SOURCE CURRENT LIMIT = 2.5A
ChargingCurrent() = 3008mA
ChargingVoltage() = 18,432mV0
SOURCE/BATT CURRENT vs. VBATT
WITH SOURCE CURRENT LIMIT
MAX1645 toc13
SOURCE/BATT CURRENT (A)
IIN
IBATT
ILOAD = 2A
VCLS = 2V
RCSS = 40mΩ
ChargingVoltage() = 18,432mV
ChargingCurrent() = 3008mA
SOURCE CURRENT LIMIT = 2.5A
Typical Operating Characteristics (continued)(Circuit of Figure 1, VDCIN= 20V, TA = +25°C, unless otherwise noted.)
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
Pin DescriptionBattery Voltage OutputBATT9
DAC Voltage Output DAC10
Logic Circuitry Supply Voltage Input (2.8V to 5.65V) VDD11
Thermistor Voltage Input THM12
SMB Clock Input SCL13
Charging Source Compensation Capacitor Connection. Connect a 0.01µF capacitor from CCS to GND.CCS5
Battery Current-Loop Compensation Capacitor Connection. Connect a 0.01µF capacitor from CCI to GND. CCI6
Battery Voltage-Loop Compensation Capacitor Connection. Connect a 10kΩresistor in series with a 0.01µF
capacitor to GND. CCV7
Ground GND8
4.096V Reference Voltage OutputREF4
Source Current Limit InputCLS3
PIN5.4V Linear-Regulator Voltage Output. Bypass with a 1µF capacitor to GND.LDO2
DC Supply Voltage InputDCIN1
FUNCTIONNAMEInductor Voltage Sense InputLX22
High-Side NMOS Driver OutputDHI23
High-Side Driver Bootstrap Voltage Input. Bypass with 0.1µF capacitor to LX.BST24
Charging Source Current-Sense Negative InputCSSN25
Charging Source Current-Sense Positive InputCSSP26
Battery Current-Sense Positive InputCSIP18
Power GroundPGND19
Low-Side NMOS Driver OutputDLO20
Low-Side NMOS Driver Supply Voltage. Bypass with 0.1µF capacitor to GND.DLOV21
Battery Current-Sense Negative InputCSIN17
PMOS Load Switch Driver OutputPDL16
Interrupt Output. Open-drain output. Needs external pull-up.INT15
SMB Data Input/Output. Open-drain output. Needs external pull-up.SDA14
Charging Source PMOS Switch Driver OutputPDS27
Charging Source Voltage InputCVS28
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
Detailed DescriptionThe MAX1645/MAX1645A consist 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 volt-
age and the current set by the SMBus interface. The
MAX1645/MAX1645A feature 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 current-
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 cur-
rent limit.
Setting Output VoltageThe MAX1645/MAX1645A voltage DACs have a 16mV
LSB and an 18.432V full scale. The SMBus specifica-
tion allows for a 16-bit ChargingVoltage() command
that translates to a 1mV LSB and a 65.535V full-scale
voltage; therefore, the ChargingVoltage() value corre-
sponds to the output voltage in millivolts. The
MAX1645/MAX1645A ignore the first four LSBs and use
the next 11 LSBs to control the voltage DAC. All codes
greater than or equal to 0b0100 1000 0000 0000
(18432mV) result in a voltage overrange, limiting the
charger voltage to 18.432V. All codes below 0b0000
0100 0000 0000 (1024mV) terminate charging.
Setting Output CurrentThe MAX1645/MAX1645A current DACs have a 64mA
LSB and a 3.008A full scale. The SMBus specification
allows for a 16-bit ChargingCurrent() command that
translates to a 1mA LSB and a 65.535A full-scale cur-
rent; the ChargingCurrent() value corresponds to the
charging voltage in milliamps. The MAX1645/
MAX1645A drop the first six LSBs and use the next
six LSBs to control the current DAC. All codes above
0b00 1011 1100 0000 (3008mA) result in a current
overrange, limiting the charger current to 3.008A. All
codes below 0b0000 0000 1000 0000 (128mA) turn the
charging current off. A 50mΩsense resistor (R2 in
Figure 1) is required to achieve the correct CODE/cur-
rent scaling.
Input Current LimitingThe MAX1645/MAX1645A limit the current drawn by the
charger when the load current becomes high. The
devices limit 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. See also 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
MAX1645/MAX1645A active while the supply to DCIN is
removed, connect an external supply to VDD.
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current LimitingLOAD
ADAPTER IN
MAX1645A
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
C23
0.1μF
1μF
100k
100k
0.1μF
0.01μF
10k
C11
0.01μF
C10
0.01μF
FDS6675D1
1N5821
22μF
22μFR1
0.04Ω
C20, 1μF
C19, 1μF
R14
4.7Ω
R15
4.7Ω
1μFD3
1N4148
R12
33Ω
C16
0.1μF
C14
0.1μFN1
FDS6680
FDS6612A
22μHD2
1N5821
10k
C12
1μFR8
10k
10k
R10
10k
C13
1.5nF
10k
0.05Ω
FDS6675C4
22μF
22μF
C18
0.1μF
R16
R11
C24
0.1μF
Figure 1. Typical Application Circuit
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers 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
MAX1645/MAX1645A
INT
Figure 2. Functional Diagram
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current Limiting
Operating ConditionsThe MAX1645/MAX1645A change their 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
considered to be in an AC Present state. In this con-
dition, both the LDO and REF will function properly
and battery charging is allowed. When AC is pre-
sent, the AC_PRESENT bit (bit 15) in the
ChargerStatus() register is set to “1.”
Power Fail.When DCIN is < BATT + 0.3V, the part is
in the Power Fail state, since the charger doesn’t
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 MAX1645/
MAX1645A use the THM pin to detect when a battery
is connected to the charger. When the battery is pre-
sent, 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 will perform a "Float" charge to minimize
contact arcing on battery connection. "Float" charge
will still try 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 will not respond to commands. Coming out of
the undervoltage condition, the part will be in its
Power-On Reset state. No charging will occur when
VDDis under voltage.
SMBus InterfaceThe MAX1645/MAX1645A receive 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 functionality complies with the Intel/Duracell
Smart Charger Specification for a Level 2 charger.
The MAX1645/MAX1645A use the SMBus Read-Word
and Write-Word protocols to communicate with the bat-
tery being charged, as well as with any host system
that monitors the battery-to-charger communications as
a Level 2 SMBus charger. The MAX1645/MAX1645A
are SMBus slave devices and do not initiate communi-
cation on the bus. They receive commands and
respond to queries for status 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 these parts 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 MAX1645/MAX1645As’ 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
MAX1645/MAX1645A comply with level 2 Smart Battery
Charger Specification Revision 1.0; therefore, the
ChargerSpecInfo() command returns 0x01.
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 THER-
MISTOR_UR = 0), the host must use the Charger
Mode() 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 Charger
Status() 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.
The ChargerStatus() command returns information
about thermistor impedance and the MAX1645/
MAX1645A’s internal state. The latched bits, THERMIS-
TOR_HOT and ALARM_INHIBITED, are cleared when-
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current LimitingFigure 3. SMBus a) Write-Word and b) 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 bits
SLAVE
ADDRESSSMSB LSB8 bits
ACK
LOW
DATA
BYTEMSB LSB8 bits
ACK
HIGH
DATA
BYTEWrite-Word Format
b) Read-Word FormatLegend:
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
NACK8 bits1b
MSB LSB1
LOW
DATA
BYTE
ACK8 bits1b
MSB LSB0
SLAVE
ADDRESSR7 bits1b
MSB LSB1
ACK
COMMAND
BYTEACK8 bits1b
MSB LSB0
ACKSLAVE
ADDRESSW7 bits1b
MSB LSB0
ever BATTERY_PRESENT = 0 or ChargerMode() is writ-
ten with POR_RESET = 1. The ALARM_INHIBITED sta-
tus bit can also be cleared by writing a new charging
current OR charging voltage.
MAX1645/MAX1645A
Advanced Chemistry-Independent, Level 2
Battery Chargers with Input Current LimitingSTART
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
