BQ25601 Datasheet, PDF (19/60 Pages) Texas Instruments – I2C Controlled 3-A, Single-Cell Battery Charger for High Input Voltage and Narrow Voltage DC (NVDC) Power Path Management

bq25601
www.ti.com
SLUSCK5 – MARCH 2017
8.4.4 Boost Mode Operation From Battery
The device supports boost converter operation to deliver power from the battery to other portable devices
through USB port. The boost mode output current rating meets the USB On-The-Go 500 mA output requirement.
The maximum output current is up to 1.2 A. The boost operation can be enabled if the conditions are valid:
1. BAT above V_{OTG_BAT}
2. VBUS less than BAT+V_SLEEP (in sleep mode)
3. Boost mode operation is enabled (OTG_CONFIG bit = 1)
4. Voltage at TS (thermistor) pin is within acceptable range (V_BHOT < V_TS < V_BCOLD)
5. After 30-ms delay from boost mode enable
in boost mode, the device employs 1.4 MHz step-up switching regulator.
During boost mode, the status register VBUS_STAT bits is set to 111, the VBUS output is 5.15 V by default and
the output current can reach up to 1.2 A, selected through I²C (BOOST_LIM bit). The boost output is maintained
when BAT is above V_{OTG_BAT} threshold.
When OTG is enabled, the device starts up with PFM and later transits to PWM to minimize the overshoot. The
PFM_DIS bit can be used to prevent PFM operation in either buck or boost configuration.
8.4.5 Host Mode and Default Mode
8.4.5.1 Host Mode and Default Mode in bq25601
The bq25601 is a host controlled charger, but it can operate in default mode without host management. in default
mode, the device can be used as an autonomous charger with no host or while host is in sleep mode. When the
charger is in default mode, WATCHDOG_FAULT bit is HIGH. When the charger is in host mode,
WATCHDOG_FAULT bit is LOW.
After power-on-reset, the device starts in default mode with watchdog timer expired, or default mode. All the
registers are in the default settings. During default mode, any change on PSEL pin will make real time IINDPM
register changes.
in default mode, the device keeps charging the battery with default 10-hour fast charging safety timer. At the end
of the 10-hour, the charging is stopped and the buck converter continues to operate to supply system load.
Writing a 1 to the WD_RST bit transitions the charger from default mode to host mode. All the device parameters
can be programmed by the host. To keep the device in host mode, the host has to reset the watchdog timer by
writing 1 to WD_RST bit before the watchdog timer expires (WATCHDOG_FAULT bit is set), or disable watchdog
timer by setting WATCHDOG bits = 00.
When the watchdog timer expires (WATCHDOG_FAULT bit = 1), the device returns to default mode and all
registers are reset to default values except IINDPM, VINDPM, BATFET_RST_EN, BATFET_DLY, and
BATFET_DIS bits.
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