19-2323; Rev 1; 9/03
Low-Power, Single/Dual-Level Battery Monitors
with Hysteresis
General Description
The MAX6427鈥揗AX6438 are single/dual-level battery mon-
itors with internal hysteresis. These devices are offered with
single (MAX6427/MAX6428/MAX6429, MAX6433/
MAX6434/MAX6435) or dual (MAX6430/MAX6431/
MAX6432, MAX6436/MAX6437/MAX6438) low-battery out-
put indicators, which can be used to indicate three battery
conditions: battery is good (operate system in normal
mode), battery is weak (operate system in low-power
mode), or battery is empty (disable the system).
These devices are ideal for monitoring single lithium-ion
(Li+) cells or multicell alkaline/NiCd/NiMH power supplies.
When the power-supply voltage drops below the specified
low threshold, the low-battery output asserts. When the
voltage rises above the specified high threshold, the low-
battery output is deasserted following a 140ms minimum
timeout period. The timeout period ensures that the supply
voltages have stabilized before power-converter or micro-
processor activity is enabled.
The MAX6427鈥揗AX6438 family is available with several
monitoring options. The MAX6427/MAX6428/MAX6429
offer factory-trimmed battery-monitor thresholds, with a sin-
gle low-battery output. The MAX6430/MAX6431/MAX6432
also feature factory-trimmed thresholds, but have two low-
battery outputs.
The MAX6433鈥揗AX6438 have user-adjustable threshold
voltages permitting the user to select the hysteresis range,
and consequently the sensitivity of the system to noise. A
wide hysteresis range also prevents chattering that can
result due to battery recovery after load removal. Single
low-battery outputs are supplied by the MAX6433/
MAX6434/MAX6435 and dual low-battery outputs by the
MAX6436/MAX6437/MAX6438.
The MAX6427鈥揗AX6438 family is available with three out-
put logic options for convenient interface with system
power circuitry or microprocessors. The family is offered in
small SOT23 and SOT143 packages and is fully specified
over temperature.
Features
o
Factory-Trimmed or User-Adjustable Threshold
Options
Factory-Trimmed Low Thresholds from 1.6V to
2.1V or 2.6V to 3.1V in 100mV Increments
(MAX6427鈥揗AX6432)
Factory-Trimmed High Thresholds from 2.3V to
2.6V or 3.3V to 3.6V in 100mV Increments
(MAX6427鈥揗AX6432)
User-Adjustable Low/High Thresholds with
615mV Internal Reference (MAX6433鈥揗AX6438)
o
Low Current (1碌A, typ)
o
Single or Dual Low-Battery Outputs
o
Push-Pull
LBO,
Open-Drain
LBO,
and Open-Drain
LBO Options
o
140ms Minimum LBO Timeout Period
o
Immune to Short Battery Voltage Transients
o
Guaranteed Valid LBO Logic State to BATT = 1.0V
o
-40掳C to +85掳C Operating Temperature Range
o
Small 3, 4, 5 and 6-Pin SOT Packages
o
No External Components Required
(MAX6427鈥揗AX6432)
MAX6427鈥揗AX6438
Ordering Information
PART
MAX6427_
_UR-T
鈥?/div>
The
TEMP RANGE
-40掳C to +85掳C
PIN-PACKAGE
3 SOT23-3
Ordering Information continued at end of data sheet.
MAX6427鈥揗AX6432 are available with factory-trimmed
battery-monitor thresholds. Select the desired thresholds
using Tables 1 or 2 and enter the corresponding letters in
the part number by replacing 鈥淿 _鈥?
Note:
There are 26 standard versions with a required order
minimum of 2500 pieces. Sample stock is generally held on
the standard versions only (see Standard Versions Table).
Required order increment is 10,000 pieces for nonstandard
versions. Contact factory for availability. All devices avail-
able in tape-and-reel only.
________________________Applications
Battery-Powered Systems (Single-Cell Li+ or
Two/Three-Cell NiMH, NiCd, Alkaline)
Cell Phones/Cordless Phones
Portable Medical Devices
Electronic Toys
Pagers
PDAs
MP3 Players
Pin Configurations
TOP VIEW
LBO
1
(LBO)
MAX6427
MAX6428
MAX6429
BATT
2
3
GND
SOT23-3
( ) ARE FOR THE MAX6429.
Typical Operating Circuit appears at end of data sheet.
Pin Configurations continued at end of data sheet.
1
________________________________________________________________
Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim鈥檚 website at www.maxim-ic.com.
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