DS2755: High-Accuracy Battery Fuel Gauge with Snapshot

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Figure 2. FUNCTIONAL DIAGRAM

1-WIRE

INTERFACE

AND

ROM ID

VOLTAGE

REFERENCE

THERMAL

SENSE

ADC

DQ

VIN

TIMEBASE

M

U

X

-

+

LOCKABLE EEPROM

BLOCKS

SRAM

TEMPERATURE

VOLTAGE

CURRENT

ACCUM. CURRENT

STATUS / CONTROL

chip ground

SNS

IS2

VSS

IS1

VDD

COMPARATORS

PIO

BIAS

DETAILED PIN DESCRIPTION

PIN

NAME

DESCRIPTION

1

VIN

Battery voltage sense input. Voltage measurement performed on VIN input and

displayed in Voltage Register.

2

VSS

Device ground and current sense resistor connection. VSS attaches to battery end

of sense resistor.

3

PIO

General purpose programmable I/O pin or optional interrupt output.

4

VDD

Input supply: +2.5V to +5.5V input range. Bypass VDD to VSS with 0.1

μF.

5

IS1

Current sense filter input 1

6

IS2

Current sense filter input 2

7

SNS

Sense resistor connection. SNS attaches to pack end of current sense resistor.

8

DQ

Serial interface data I/O pin. Bidirection data transmit and receive at 16kbps or

143kbps. Optional interrupt output.

POWER MODES

The DS2755 has two power modes: Active and Sleep. While in Active mode, the DS2755 continuously measures

current, voltage and temperature. Current accumulation and monitoring for under voltage also occur continuously in

Active

mode. In Sleep mode, the DS2755 ceases these activities. The DS2755 enters Sleep mode when PMOD =

1 AND either of the following occur:

(DQ low used indicate that the pack has been disconnected or that the host system is signaling the

DS2755 to enter Sleep mode.)

power is first applied.