DS2764 High-Precision Li+ Battery Monitor With 2-Wire Interface

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Figure 2. Block Diagram

DETAILED DESCRIPTION

The DS2764 high-precision Li+ battery monitor is a data-acquisition, information-storage, and safety-protection

device tailored for cost-sensitive battery pack applications. This low-power device integrates precise temperature,

voltage, and current measurement, nonvolatile (NV) data storage, and Li+ protection into the small footprint of

either a TSSOP package or flip-chip package. The DS2764 is a key component in applications including remaining

capacity estimation, safety monitoring, and battery-specific data storage.

Through its 2-Wire interface, the DS2764 gives the host system read/write access to status and control registers,

instrumentation registers, and general-purpose data storage. The 7-bit slave address is field programmable, thus

allowing up to 128 devices to be distinctly addressed by the host system.

The DS2764 is capable of performing temperature, voltage, and current measurement to a resolution sufficient to

support process monitoring applications such as battery charge control, remaining capacity estimation, and safety

monitoring. Temperature is measured using an on-chip sensor, eliminating the need for a separate thermistor.

Bidirectional current measurement and accumulation are accomplished using either an internal 25m

W sense

resistor or an external device.

EEPROM memory is provided to save important battery data in true NV memory that is unaffected by severe

battery depletion, accidental shorts, or ESD events. 40 bytes are partitioned into two 16-byte blocks and one 8-byte

block. Each block can be individually locked or write protected to provide additional security for unchanging battery

data. The lock operation is permanent and thus converts rewritable EEPROM to read only memory. Devices

ordered with the unique 64-bit ID option do not have access to the 8 byte block, only the two 16 byte blocks of

EEPROM are available.

2-Wire

INTERFACE

THERMAL

SENSE

MUX

VOLTAGE

REFERENCE

ADC

REGISTERS AND

USER MEMORY

25m

W

SDA

CHIP GROUND

+

-

LOCKABLE EEPROM

TEMPERATURE

VOLTAGE

CURRENT

ACCUM. CURRENT

STATUS/CONTROL

Li+ PROTECTION

IS1

IS2

SNS

IS2

IS1

CC

DC

PLS

PS

TIMEBASE

INTERNAL SENSE RESISTOR

CONFIGURATION ONLY

DS2764

SCL