DS2438

Smart Battery Monitor

FEATURES

♦Unique 1-Wire® interface requires only one port pin for communication

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Provides unique 64-bit serial number

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Eliminates thermistors by sensing battery temperature on-chip

♦On-board A/D converter allows monitoring of battery voltage for end-of-charge and endof-discharge determination

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On-board integrated current accumulator facilitates fuel gauging

♦Elapsed time meter in binary format

♦40-byte nonvolatile user memory available for storage of battery-specific data

♦Reverts to low-power sleep mode on battery pack disconnect (feature disabled on DS2438AZ)

♦Operating range -40ºC to +85ºC

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Applications include portable computers, portable/cellular phones, consumer electronics, and handheld instrumentation PIN ASSI

PIN DESCRIPTION

DQ - Data In/Out

VAD - General A/D input

VSENS+ - Battery current monitor input (+)

VSENS- - Battery current monitor input (-)

VDD - Power Supply (2.4V to 10.0V)

GND - Ground NC - No connect

DESCRIPTION

The DS2438 Smart Battery Monitor provides several functions that are desirable to carry in a battery pack: a means of tagging a battery pack with a unique serial number, a direct-to-digital temperature sensor which eliminates the need for thermistors in the battery pack, an A/D converter which measures the battery voltage and current, an integrated current accumulator which keeps a running total of all current going into and out of the battery, an elapsed time meter, and 40 bytes of nonvolatile EEPROM memory for storage of important parameters such as battery chemistry, battery capacity, charging methodology and assembly date. Information is sent to/from the DS2438 over a 1-Wire interface, so that only one wire (and ground) needs to be connected from a central microprocessor to a DS2438. This means that battery packs need only have three output connectors: battery power, ground, and the 1-Wire interface.