MAX1925 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – Switch-Mode 1-Cell Li+ Chargers

19-2556; Rev 1; 10/02
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Switch-Mode 1-Cell Li+ Chargers
General Description
The MAX1925/MAX1926 single-cell lithium-ion (Li+)
switch-mode battery chargers use an external PMOS
pass element step-down configuration. Charge current
is programmable, and an external capacitor sets the
maximum charge time.
Additional features include automatic input power
detection (ACON output), logic-controlled enable, and
temperature monitoring with an external thermistor. The
MAX1925 disables charging for inputs greater than
6.1V, while the MAX1926 charges for inputs between
4.25V and 12V.
The MAX1925/MAX1926 feature two precondition levels
to restore near-dead cells. The devices source 4mA to
a cell that is below 2V while sourcing C/10 to a cell
between 2V and 3V. Full charge current is then applied
above 3V. A CHG output drives an LED to indicate
charging (LED on) and fault conditions (LED blinking).
The MAX1925/MAX1926 are available in a 12-pin
4mm ✕ 4mm thin QFN package and are specified over
the extended temperature range (-40°C to +85°C). An
evaluation kit is available to speed design.
Applications
Digital Cameras
Self-Charging Battery Packs
PDAs
Cradle Chargers
Features
o Small (4mm ✕ 4mm) Package
o 4.25V to 12V Input Range (MAX1926)
o Overvoltage Lockout at 6.1V (MAX1925)
o ±0.75% Battery Regulation Voltage
o Set Charge Current with One Resistor
o Automatic Input Power Sense
o LED (or Logic-Out) Charge Status and Fault
Indicator
o Programmable Safety Timer
o Autorestart at Cell = 4V
o Thermistor Monitor Input
Ordering Information
PART
TEMP
RANGE
PIN-
PACKAGE
INPUT
CHARGING
RANGE
MAX1925ETC
-40°C to +85°C
12 Thin QFN
4mm x 4mm
4.5V to 6.1V
MAX1926ETC
-40°C to +85°C
12 Thin QFN
4mm x 4mm
4.25V to 12V
Pin Configuration
IN INP EXT
12 11 10
CHG 1
EN 2
THRM 3
MAX1925
MAX1926
9 PGND
8 GND
7 BATT
4
5
6
ACON CT CS
THIN QFN
INPUT
4.5V TO 12V
Typical Operating Circuit
IN
LED
CHG
CT
ON
OFF
EN
INP EXT PGND
CS
MAX1925
MAX1926
ACON
BATT
GND
THRM
1-CELL
Li+
BATTERY
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