MAX1894 Datasheet, PDF (1/16 Pages) Maxim Integrated Products – Advanced Li+ Battery-Pack Protectors

19-2278; Rev 0; 4/02
Advanced Li+ Battery-Pack Protectors
General Description
The MAX1894/MAX1924 are lithium-ion/lithium-polymer
(Li+) battery-pack protector ICs for 3- or 4-series Li+ bat-
tery packs. The MAX1894/MAX1924 enhance the useful
operating life of Li+ batteries by monitoring individual cell
voltages and preventing over/undervoltage conditions.
The MAX1894/MAX1924 also protect the battery pack
against charge current, discharge current, and pack-
short fault conditions.
In case of a fault condition, on-board drivers control
external P-channel MOSFETs, which disconnect the cells
from the pack external terminals. The external protection
MOSFETs are connected in a common-source configura-
tion that does not require external pullup resistors. The
MAX1894/MAX1924 use only one current-sense resistor
to achieve the protection features. All protection thresh-
olds and delays do not require any external components
and are trimmed at the factory.
If any cell voltage drops below the undervoltage thresh-
old, the MAX1894/MAX1924 disconnect the pack from
the load and power down to prevent deep discharge of
the pack. The MAX1894/MAX1924 offer a trickle-charge
feature, which provides a low-current path to safely
charge a deeply discharged pack. The MAX1894/
MAX1924 also have two logic-level inputs, which can be
used by a microcontroller to disable the protection
MOSFETs and to put the device in shutdown. The
MAX1894/MAX1924 have low quiescent current (30µA
typ) and ultra-low shutdown current (0.8µA typ) to pre-
vent deep-cell discharge.
The MAX1894X is designed for 4-series battery packs,
without hysteresis on the protection thresholds. The
MAX1924V and MAX1924X include hysteresis for the 3-
and 4-series packs, respectively.
Applications
3- or 4-Series Li+ Battery Packs
Features
o Protect Against Cell Overvoltage
Factory Programmable Limits from 4V to 4.4V
Accurate to ±0.5%
o Protect Against Cell Undervoltage
Factory Programmable Limits from 2V to 3.2V
Accurate to ±2.0%
o Protect Against Charge, Discharge, and Pack-
Short Current Faults
o Automatically Trickle Charges Deeply Discharged
Cells
o Fully Integrated MOSFET Drivers Do Not Require
Pullup Resistors
o 0.8µA (typ) Shutdown Supply Current Prevents
Deep Discharge of Cells
o 30µA (typ) Operating Supply Current
o 28V (max) Input Voltage
o Available in Small 16-Pin QSOP Package
Pin Configuration
TOP VIEW
B4P 1
V_CC 2
B3P 3
IC3 4
B2P 5
IC2 6
B1P 7
IC1 8
MAX1894
MAX1924
16 SRC
15 DSO
14 CGO
13 TKO
12 SHDN
11 CTL
10 PKN
9 BN
QSOP
Ordering Information
PART
TEMP RANGE PIN-PACKAGE
MAX1894XEEE
-40°C to +85°C 16 QSOP
MAX1924VEEE
-40°C to +85°C 16 QSOP
MAX1924XEEE
-40°C to +85°C 16 QSOP
*Contact factory for alternative threshold voltages.
Typical Applications Circuits appear at end of data sheet.
CELLS
4
3
4
OVERVOLTAGE
4.25V*
4.35V*
4.35V*
OVERVOLTAGE
THRESHOLD HYSTERESIS
No
Yes
Yes
________________________________________________________________ Maxim Integrated Products 1
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