Charge Status Output, STAT Pin

Control Bits in Charge Mode

bq24150

bq24151

battery voltage is still above recharge threshold, the battery is present and the charge done is detected.

However, if the battery voltage is below battery recharge threshold, the battery is absent. Under this condition,

the charge parameters (such as input current limit) are reset to the default values and charge resumes after a

battery is replaced.

Battery Detection at Power Up

The bq24150 has a unique battery detection scheme during the start up of the charger. At VBUS power up, if the

timer is in 32-minute mode, the bq24150 starts a 32ms timer when exiting from short circuit mode to PWM

yet expired, the bq2150 determines battery is not present; then stops charging and immediately goes to the high

impedance mode. However, if the 32ms timer is expired when the recharge threshold is reached, the charging

process continues as a normal battery charging process. This unique feature makes bq24150 compatible with

USB charging specifications.

Battery Short Protection

The STAT pin is used to indicate operation conditions for bq24150/1. STAT is pulled low during charging and

EN_STAT bit in control register (00H) is set to "1". Under other conditions, the STAT pin acts as a high

impedance (open-drain) output. Under fault conditions, a 128-

µs pulse is sent out to notify the host. The status of

STAT pin at different operation conditions is summarized in Table 1. The STAT pin can be used to drive an LED

or communicate to the host processor.

Table 1. STAT Pin Summary

Charge State

STAT

Charge in progress and EN_STAT=1

Low

Other normal conditions

Open-drain

Charge mode faults: Timer fault, sleep mode, VBUS 128-

µs pulse, then open-drain

or battery overvoltage, poor input source, VBUS

UVLO, no battery, thermal shutdown

Boost mode faults: Timer fault, over load, VBUS or

128-

µs pulse, then open-drain

battery overvoltage, low battery voltage, thermal

shutdown

CE Bit (Charge Mode)

The bit of CE in control register is used to disable or enable the charge process. A low logic level (0) on this bit

enables the charge and a high logic level (1) disables the charge.

RESET Bit

The bit of RESET in control register is used to reset all the charge parameters. Writing '1" to RESET bit resets all

the charge parameters to default values and RESET bit is automatically cleared to zero once the charge

parameters are reset. It is designed for charge parameter reset before charge starts, and it is not recommended

to set the RESET bit when charging or boosting in progress.

OPA_Mode Bit

OPA_MODE is the operation mode control bit. When OPA_MODE = 0, the bq24150/1 charges the related

operation modes if HZ_MODE is set to "0", refer to Table 2 for detail.

Copyright © 2008, Texas Instruments Incorporated

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