BQ24157S Datasheet, PDF (19/45 Pages) Texas Instruments – Full USB Compliance and USB-OTG Support

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bq24157S
SLUSB76B – FEBRUARY 2013 – REVISED MAY 2015
Feature Description (continued)
8.3.11 Charge Status Output, STAT Pin
The STAT pin is used to indicate operation conditions. STAT is pulled low during charging when EN_STAT bit in
control register (00H) is set to 1. Under other conditions, STAT pin behaves as a high impedance (open-drain)
output. Under fault conditions, a 128-µs pulse will be sent out to notify the host. The status of STAT pin at
different operation conditions is summarized in Table 2. The STAT pin can be used to drive an LED or
communicate to the host processor.
Table 2. STAT Pin Summary
Charge State
Charge in progress and EN_STAT = 1
Other normal conditions
Charge mode faults: Timer fault, sleep mode, VBUS 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
Stat
Low
Open-drain
128-μs pulse, then open-drain
128-μs pulse, then open-drain
8.3.12 Control Bits in Charge Mode
8.3.12.1 CE Bit (Charge Mode)
The CE bit in the 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.
8.3.12.2 RESET Bit
The RESET bit in the Battery Termination/Fast Charge Current register is used to reset all the charge
parameters. Writing 1 to the RESET bit will reset all the charge parameters to default values except the safety
limit register, and RESET bit is automatically cleared to 0 when the charge parameters are reset. It is designed
for charge parameter reset before charge starts and TI does not recommended to set the RESET bit while
charging or boosting are in progress.
8.3.12.3 OPA_MODE Bit
OPA_MODE is the operation mode control bit. When OPA_MODE = 0, the IC operates as a charger; if
HZ_MODE is set to 0, refer to Table 3 for details. When OPA_MODE = 1 and HZ_MODE = 0, the IC operates in
boost mode.
OPA_MODE
0
1
X
Table 3. Operation Mode Summary
HZ_MODE
Operation Mode
Charge (no fault)
0
Charge configure (fault, V_bus > UVLO)
High impedance (V_bus < UVLO)
0
Boost (no faults)
Any fault go to charge configure mode
1
High impedance
8.3.13 Control Pins in Charge Mode
8.3.13.1 CD Pin (Charge Disable)
The CD pin is used to disable the charging process. When the CD pin is low, charge is enabled. When the CD
pin is high, charge is disabled and the charger enters high impedance (Hi-Z) mode.
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