19-2278; Rev 0; 4/02
Advanced Li+ Battery-Pack Protectors
General Description
Features
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.
ꢀ Protect Against Cell Overvoltage
Factory Programmable Limits from 4V to 4.4V
Accurate to ±±.ꢀ5
ꢀ Protect Against Cell Undervoltage
Factory Programmable Limits from 2V to 3.2V
Accurate to ±2.±5
ꢀ Protect Against Charge, Discharge, and Pack-
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.
Short Current Faults
ꢀ Automatically Trickle Charges Deeply Discharged
Cells
ꢀ Fully Integrated MOSFET Drivers Do Not Require
Pullup Resistors
ꢀ ±.8µA (typ) Shutdown Supply Current Prevents
Deep Discharge of Cells
ꢀ 3±µA (typ) Operating Supply Current
ꢀ 28V (max) Input Voltage
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.
ꢀ Available in Small 16-Pin QSOP Package
Pin Configuration
TOP VIEW
B4P
1
2
3
4
5
6
7
8
16 SRC
15 DSO
V
CC
CGO
14
B3P
IC3
B2P
IC2
B1P
IC1
13 TKO
12 SHDN
11 CTL
10 PKN
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.
MAX1894
MAX1924
9
BN
Applications
QSOP
3- or 4-Series Li+ Battery Packs
Ordering Information
OVERVOLTAGE
THRESHOLD HYSTERESIS
PART
TEMP RANGE
PIN-PACKAGE
CELLS
OVERVOLTAGE
MAX1894XEEE
MAX1924VEEE
MAX1924XEEE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
16 QSOP
16 QSOP
16 QSOP
4
3
4
4.25V*
4.35V*
4.35V*
No
Yes
Yes
*Contact factory for alternative threshold voltages.
Typical Applications Circuits appear at end of data sheet.
________________________________________________________________ Maxim Integrated Products
1
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.