19-1796; Rev 1; 1/03

Power Source Selector for

Dual-Battery Systems

General Description

Features

The MAX1773/MAX1773A highly integrated ICs serveas the control logic for a system with multiple poweroPatented 7-MOSFET Topology Offers Low-Costsources. They directly drive external P-channelSolutionMOSFETs to select from an AC adapter and dual bat-oAutomatically Detects and Responds to:

tery sources for charge and discharge. The selection isLow Battery Voltage Conditionmade based on the presence of the power sources andBattery Insertion and Removalthe state of the batteries. The MAX1773/MAX1773Adetect low battery conditions using integrated analogAC Adapter Presencecomparators and check for the presence of a batteryoDirect Drive of P-Channel MOSFETsby using battery thermistor outputs.

oSimplifies Power Management µP FirmwareThe MAX1773/MAX1773A are designed for use with abuck topology charger. They provide a simple and easilyoExtends Battery Life by Allowing Powercontrolled solution to a difficult analog power control prob-Management µP to Enter Standbylem. The MAX1773/MAX1773A provide most of the powero4.75V to 28V AC Adapter Input Voltage Rangesource monitoring and selection, freeing the system powermanagement microprocessor (µP) for other tasks. This notoIntegrated LDO with 1mA Drive Capabilityonly simplifies development of the power managementoSmall Footprint 20-Pin TSSOP Package

firmware for the µP but also allows the µP to enter standby,thereby reducing system power consumption.

Ordering Information

The MAX1773A is recommended for new designs.

________________________Applications

Notebook and Subnotebook Computers PDAs and Handy-TerminalsPin Configuration appears at end of data sheet.

Internet Tablets

Dual-Battery Portable Equipment

Covered by U.S. Patent number 5,764,032.

Typical Operating Circuit

________________________________________________________________Maxim Integrated Products1

For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at http://.

MAX1773/MAX1773A

Power Source Selector for Dual-Battery SystemsMAX1773/MAX1773A

ABSOLUTE MAXIMUM RATINGS

VBATA, VBATBto GND............................................-0.3V to +20VVCOMAto GND........................................-0.3V to (VBATA+ 0.3V)VCOMBto GND........................................-0.3V to (VBATB+ 0.3V)VCHGA, VCHGB, VEXTLD, VACDETto GND..............-0.3V to +30VVPDS, VDISA, VDISBto GND...................-0.3V to (VEXTLD+ 0.3V)VDD, VBATSEL, VACPRES, VBATSTAT, VTCOMP,

VMINVto GND.......................................................-0.3V to +6VVTHMA, VTHMB (Note 1)............................................ -0.3V to +6V

Continuous Current out of THMA, THMB............................20mAIACPRES, IBATSTATSink Current..........................................30mAContinuous Power Dissipation (TA= +70°C)

20-Pin TSSOP (derate 7.0mW/°C above +70°C)........560mWOperating Temperature ......................................-40°C to +85°CStorage Temperature ........................................-65°C to +150°CLead Temperature (soldering, 10s).................................+300°C

Note 1:Signals on THMA and THMB below -0.3V are clamped by internal diodes limit forward diode current to maximum continuous current. When voltageon these pins is below -0.3V.

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functionaloperation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure toabsolute maximum rating conditions for extended periods may affect device reliability.

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.)

2_______________________________________________________________________________________

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,

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MAX1773/MAX1773A

Power Source Selector for Dual-Battery Systems

MAX1773/MAX1773A

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.)

(VBATA= VBATB= 16.8V, CVDD= 3.3µF, VMINV= 0.93V, VEXTLD= VACDET= 28V, VTCOMP= 3V, VTHMA= VTHMB= 1.65V,

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.)

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MAX1773/MAX1773A

Power Source Selector for Dual-Battery Systems

MAX1773/MAX1773A

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.)“absent” (VTHM_> VTCOMP).

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