
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
General Description
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 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.
________________________Applications
Notebook and Subnotebook Computers
PDAs and Handy-Terminals
Internet Tablets
Dual-Battery Portable Equipment
Features
o
Patented
7-MOSFET Topology Offers Low-Cost
Solution
o
Automatically Detects and Responds to:
Low Battery Voltage Condition
Battery Insertion and Removal
AC Adapter Presence
o
Direct Drive of P-Channel MOSFETs
o
Simplifies Power Management μP Firmware
o
Extends Battery Life by Allowing Power
Management μP to Enter Standby
o
4.75V to 28V AC Adapter Input Voltage Range
o
Integrated LDO with 1mA Drive Capability
o
Small Footprint 20-Pin TSSOP Package
M
Power Source Selector for
Dual-Battery Systems
________________________________________________________________
Maxim Integrated Products
1
19-1796; Rev 1; 1/03
EVALUATION KIT
AVAILABLE
Ordering Information
Pin Configuration appears at end of data sheet.
PART
TEMP. RANGE
-40°C to +85°C
-40°C to +85°C
PIN-PACKAGE
20 TSSOP
20 TSSOP
MAX1773
EUP
MAX1773A
EUP
Covered by U.S. Patent number 5,764,032.
Typical Operating Circuit
MAX1773
MAX1773A
EXTLD
TCOMP
MINV
V
DD
THMB
BATB
CHGB
CHGA
BATSTAT
BATSEL
SYSTEM LOGIC SUPPLY
AC ADAPTER
INPUT
3.3V
BATA
COMA
DISA
COMB
DISB
THMA
PDS
ACDET
ACPRES
3.3V
BATTERY
A
BATTERY
B
OUTPUT
3.3V DC-DC
COINPUT
SYSTEM LOAD
INPUT
STEP-DOWN
COUTPUT
FROM HOST
μ
P
TO HOST
μ
P