Features

➤ Conservative and repeatable

measurement of available charge

in rechargeable batteries

➤ Designed for portable equipment

such as power tools with high discharge

rates

➤ Designed for battery pack integration

- 120μA typical standby current

(self-discharge estimation mode)

- Small size enables implementations

in as little as 1

2

square inch of PCB

➤ Direct drive of LEDs for capacity

display

➤ Self-discharge compensation using

internal temperature sensor

➤ Simple single-wire serial communications

port for subassembly

testing

➤ 16-pin narrow SOIC

General Description

The bq2011 Gas Gauge IC is intended

for battery-pack installation to maintain

an accurate record of available

battery charge. The IC monitors a

voltage drop across a sense resistor

connected in series between the negative

battery terminal and ground to

determine charge and discharge activity

of the battery. The bq2011 is

designed for systems such as power

tools with very high discharge rates.

Battery self-discharge is estimated

based on an internal timer and temperature

sensor. Compensations for

battery temperature and rate of

charge or discharge are applied to

the charge, d i s charge, and

selfdischarge calculations to provide

available charge information across

a wide range of operating conditions.

Initial battery capacity is set using

the PFC and MODE pins. Actual

battery capacity is automatically

“learned” in the course of a discharge

cycle from full to empty and

may be displayed depending on the

display mode.

Nominal available charge may be directly

indicated using a five-segment

LED display. These segments

are used to indicate graphically the

nominal available charge.

The bq2011 supports a simple singleline

bidirectional serial link to an external

processor (common ground). The

bq2011 outputs battery information in

response to external commands over the

serial link. To support subassembly

testing, the outputs may also be controlled

by command. The external processor

may also overwrite some of the

bq2011 gas gauge data registers.

The bq2011 may operate directly

from four cells. With the REF output

and an external transistor, a simple,

inexpensive regulator can be built to

provide VCC from a greater number

of cells.

Internal registers include available

charge, temperature, capacity, battery

ID, and battery status.