www.ti.com

Gas Gauging

LED Display

LifeTime Data Logging Features

Authentication

Power Modes

CONFIGURATION

Oscillator Function

bq20z80

bq20z80A

SLUS782 – JULY 2007

FEATURE SET (continued)

The bq20z80 uses the Impedance Track™ Technology to measure and calculate the available charge in battery

cells. The achievable accuracy is better than the coulomb counting method over the lifetime of the battery and

there is no full charge discharge learning cycle required.

See Theory and Implementation of Impedance Track Battery Fuel-Gauging Algorithm application note

(SLUA364) for further details.

The bq20z80 can drive 3-, 4-, or 5- segment LED display for remaining capacity indication.

The bq20z80 offers a lifetime data logging array, where all important measurements are stored for warranty and

analysis purposes. The data monitored includes:

• Lifetime maximum temperature

• Lifetime minimum temperature

• Lifetime maximum battery cell voltage

• Lifetime minimum battery cell voltage

• Lifetime maximum battery pack voltage

• Lifetime minimum battery pack voltage

• Lifetime maximum charge current

• Lifetime maximum discharge current

• Lifetime maximum charge power

• Lifetime maximum discharge power

• Lifetime maximum average discharge current

• Lifetime maximum average discharge power

• Lifetime average temperature

The bq20z80 supports authentication by the host using SHA-1.

The bq20z80 supports 3 different power modes to reduce power consumption:

• In Normal Mode, the bq20z80 performs measurements, calculations, protection decision, data update in 1

second intervals. Between these intervals, the bq20z80 is in a reduced power stage.

• In Sleep Mode, the bq20z80 performs measurements, calculations, protection decision, data update in

adjustable time intervals. Between these intervals, the bq20z80 is in a reduced power stage.

• In Shutdown Mode the bq20z80 is completely disabled.

The oscillator of the bq20z80 can be set up for internal or external operation. On power up, the bq20z80

automatically attempts to start the internal oscillator. If a 100-k

Ω resistor is not connected to ROSC (pin 33),

then it attempts to start the oscillator using an external 32.768-kHz crystal.

NOTE

Install either the 100-k

Ω ROSC resistor or the 12-pF, 32.768-kHz crystal. Do not

install both.

9

Submit Documentation Feedback