MAX1773A

Patented† 7-MOSFET Topology Offers Low-Cost Solution
 Automatically Detects and Responds to: Low Battery Voltage Condition Battery Insertion and Removal AC Adapter Presence
 Direct Drive of P-Channel MOSFETs
 Simplifies Power Management P Firmware
 Extends Battery Life by Allowing Power Management P to Enter Standby
 4.75V to 28V AC Adapter Input Voltage Range
 Integrated LDO with 1mA Drive Capability
 Small Footprint 20-Pin TSSOP Package

Notebook and Subnotebook Computers PDAs and Handy-Terminals Internet Tablets Dual-Battery Portable Equipment

VBATA, VBATB to GND ............................................-0.3V to +20V
VCOMA to GND........................................-0.3V to (VBATA + 0.3V)
VCOMB to GND........................................-0.3V to (VBATB + 0.3V)
VCHGA, VCHGB, VEXTLD, VACDET to GND ...............0.3V to +30V
VPDS, VDISA, VDISB to GND..................-0.3V to (VEXTLD + 0.3V)
VDD, VBATSEL, V ACPRES, VBATSTAT, VTCOMP,
VMINV to GND......................................................,,,.-0.3V to +6V
VTHMA, VTHMB (Note 1).......................................... -0.3V to +6V
Continuous Current out of THMA, THMB..............................20mA
I ACPRES, IBATSTAT Sink Current........................................30mA
Continuous Power Dissipation (TA = +70)
20-Pin TSSOP (derate 7.0mW/ above +70) ...............560mW
Operating Temperature ........................................-40 to +85
Storage Temperature ..........................................-65 to +150
Lead Temperature (soldering, 10s) ...................................+300

The 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 battery 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/MAX1773Adetect low battery conditions using integrated analogcomparators 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 problem. The MAX1773/MAX1773A provide most of the power source monitoring and selection, freeing the system power management microprocessor (P) for other tasks. This not only simplifies development of the power management firmware for the P but also allows the P to enter standby, thereby reducing system power consumption.

The MAX1773A is recommended for new designs.