MAX1773AEUP ,Power Source Selector for Dual-Battery SystemsMAX1773/MAX1773A19-1796; Rev 1; 1/03Power Source Selector for Dual-Battery Systems
MAX1773AEUP+ ,Power Source Selector for Dual-Battery SystemsApplications MAX1773AEUP -40°C to +85°C 20 TSSOPNotebook and Subnotebook Computers PDAs and Handy-T ..
MAX1773EUP ,Power Source Selector for Dual-Battery SystemsFeatures† The MAX1773/MAX1773A highly integrated ICs serve Patented 7-MOSFET Topology Offers Low-C ..
MAX1774EEI ,Dual, High-Efficiency, Step-Down Converter with Backup Battery SwitchoverApplications
MAX1773AEUP-MAX1773AEUP+-MAX1773EUP
Power Source Selector for Dual-Battery Systems
General DescriptionThe MAX1773/MAX1773A highly integrated ICs serve
as the control logic for a system with multiple power
sources. They directly drive external P-channel
MOSFETs to select from an AC adapter and dual bat-
tery sources for charge and discharge. The selection is
made based on the presence of the power sources and
the state of the batteries. The MAX1773/MAX1773A
detect low battery conditions using integrated analog
comparators and check for the presence of a battery
by using battery thermistor outputs.
The MAX1773/MAX1773A are designed for use with a
buck topology charger. They provide a simple and easily
controlled solution to a difficult analog power control prob-
lem. The MAX1773/MAX1773A provide most of the power
source monitoring and selection, freeing the system power
management microprocessor (µP) for other tasks. This not
only simplifies development of the power management
firmware for the µP but also allows the µP to enter standby,
thereby reducing system power consumption.
The MAX1773A is recommended for new designs.
________________________ApplicationsNotebook and Subnotebook Computers
PDAs and Handy-Terminals
Internet Tablets
Dual-Battery Portable Equipment
FeaturesPatented† 7-MOSFET Topology Offers Low-Cost
SolutionAutomatically Detects and Responds to:
Low Battery Voltage Condition
Battery Insertion and Removal
AC Adapter PresenceDirect Drive of P-Channel MOSFETsSimplifies Power Management µP FirmwareExtends Battery Life by Allowing Power
Management µP to Enter Standby4.75V to 28V AC Adapter Input Voltage RangeIntegrated LDO with 1mA Drive CapabilitySmall Footprint 20-Pin TSSOP Package
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems19-1796; Rev 1; 1/03
Ordering Information
Pin Configuration appears at end of data sheet.Covered by U.S. Patent number 5,764,032.
Typical Operating Circuit
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
ABSOLUTE MAXIMUM RATINGSStresses 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.
VBATA, VBATBto GND............................................-0.3V to +20V
VCOMAto GND........................................-0.3V to (VBATA+ 0.3V)
VCOMBto GND........................................-0.3V to (VBATB+ 0.3V)
VCHGA, VCHGB, VEXTLD, VACDETto GND..............-0.3V to +30V
VPDS, VDISA, VDISBto GND...................-0.3V to (VEXTLD+ 0.3V)
VDD, VBATSEL, VACPRES, VBATSTAT, VTCOMP,
VMINVto GND.......................................................-0.3V to +6V
VTHMA, VTHMB (Note 1)............................................ -0.3V to +6V
Continuous Current out of THMA, THMB............................20mA
IACPRES, IBATSTATSink Current..........................................30mA
Continuous Power Dissipation (TA= +70°C)
20-Pin TSSOP (derate 7.0mW/°C above +70°C)........560mW
Operating Temperature ......................................-40°C to +85°C
Storage Temperature ........................................-65°C to +150°C
Lead Temperature (soldering, 10s).................................+300°C
ELECTRICAL CHARACTERISTICS(VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
VBATSEL= 0, CCOMA= CCOMB= CDISA= CDISB= CCHGA= CCHGB= CPDS= 5nF, TA
= 0°C to +85°C,unless otherwise noted.)
Note 1:Signals on THMA and THMB below -0.3V are clamped by internal diodes limit forward diode current to maximum continuous current. When voltage
on these pins is below -0.3V.
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)(VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)(VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
VBATSEL= 0, CCOMA= CCOMB= CDISA= CDISB= CCHGA= CCHGB= CPDS= 5nF, TA
= 0°C to +85°C,unless otherwise noted.)
ELECTRICAL CHARACTERISTICS (VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
ELECTRICAL CHARACTERISTICS (continued)(VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
VBATSEL= 0, CCOMA= CCOMB= CDISA= CDISB= CCHGA= CCHGB= CPDS= 5nF, TA
= -40°C to +85°C,unless otherwise noted.)
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
Note 2:TCOMP undervoltage lockout sets the MAX1773/MAX1773A’s internal status bits for the batteries to be designated as
“absent” (VTHM_> VTCOMP).
Note 3:VACDETmust remain above 2.2V, except in power-up.
Note 4:COMA cannot sink current until VCOMB> VBATB- 2V. Likewise, COMB cannot sink current until VCOMA> VBATA- 2V.
Note 5:DISA cannot sink current until VDISB> VEXTLD- 2V. Likewise, DISB cannot sink current until VDISA> VEXTLD- 2V.
Note 6:Battery Switchover Delay starts when either VCOM_or VDIS_of the connected battery begins to rise and ends when both
VCOM_and VDIS_of the other battery have fallen 3V below their sources (Figures 1 and 2).
Note 7:Battery Action Delay starts when the connected battery’s voltage falls below 5 ✕VMINVand ends when both VCOM_and
VDIS_of the other battery have fallen 3V below their sources (Figures 1 and 2).
Note 8:Thermistor Action Delay begins when VTHM_of the connected battery rises above VTCOMPand ends when both VCOM_
and VDIS_of the other battery have fallen 3V below their sources (Figures 3 and 4).
Note 9:AC to Battery Switchover Delay begins when VACDETfalls below its threshold and ends when both VCOM_and VDIS_of the
battery being switched to have fallen 3V below their sources (Figure 5).
Note 10:Battery to AC Switchover Delay begins when VACDETrises above its threshold and ends when VDIS_of the battery being
switched from has begun to rise (Figure 6).
Note 11:CHG_ Turn-on Delay begins when VCHG_of the battery being switched from begins to rise and ends when VCHG_of the
battery being switched to begins to fall (Figures 7 and 8).
ELECTRICAL CHARACTERISTICS (continued) (VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,
VBATSEL= 0, CCOMA= CCOMB= CDISA= CDISB= CCHGA= CCHGB= CPDS= 5nF, TA
= -40°C to +85°C,unless otherwise noted.)
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
Typical Operating Characteristics(TA = +25°C, unless otherwise noted.)
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
Typical Operating Characteristics (continued)(TA = +25°C, unless otherwise noted.)
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
MAX1773/MAX1773A
Power Source Selector for
Dual-Battery Systems
Transition Time Diagrams(VCOM_GS = COM_ turn-on clamp voltage, VDIS_GS = DIS_ turn-on clamp voltage, VCHARGER = system step-down charger output.)
Figure 1. Battery Delay (Battery A to Battery B)Figure 2. Battery Delay (Battery B to Battery A)
Figure 3. Thermistor Switchover Delay (Battery A to Battery B)
Figure 4. Thermistor Switchover Delay (Battery B to Battery A)
