BQ24150 Datasheet, PDF (19/39 Pages) Texas Instruments – Fully Integrated Switch-Mode One-Cell Li-Ion Charger with Full USB Compliance and USB-OTG Support

bq24150
bq24151
www.ti.com ...................................................................................................................................................................................................... SLUS824 – JUNE 2008
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
delay of T_INT, as shown in Figure 23. This function ensures that the charge parameters are reset whenever the
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
charge mode. If the battery voltage is charged to recharge threshold (V_(OREG) – V_(RCH)) and the 32ms timer is not
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
During the normal charging process, if the battery voltage is lower than the short-circuit threshold, V_(SHORT), the
charger operates in linear charge mode with a lower charge rate of I_(SHORT), as shown in Figure 22.
Charge Status Output, STAT Pin
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
battery overvoltage, low battery voltage, thermal
shutdown
128-µs pulse, then open-drain
Control Bits in Charge Mode
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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