Datasheet

Start Safety Timer
Charge Done?
I
CHG
< I
TERM
No
STAT = Hi
Update STAT
bits
I2C Read/Write
performed?
Start 30 second
watchdog timer
No
Yes
30s timer expired?
No
Yes
Received SW watchdog
RESET?
No
Yes
Safety timer expired?
No
Yes
Safety timer
fault
Charging suspended
Enter suspended
mode
Fault indicated in
STAT registers
Yes
Charge Done?
I
CHG
< I
TERM
No
STAT = Hi
Update STAT
bits
Yes
Reset 30 second
watchdog timer
Reset to default
values in I2C
register
Restart 27min
safety timer
Safety timer expired?
Safety timer
fault
Charging suspended
Fault indicated in
STAT registers
No
Yes
bq24160, bq24160A
bq24161, bq24161B
bq24163, bq24168
SLUSAO0E –NOVEMBER 2011–REVISED NOVEMBER 2013 www.ti.com
Safety Timer and Watchdog Timer (bq24160/ bq24161/ bq24161B/ bq24163 only)
At the beginning of charging process, the bq24160/1/1B/3 starts the safety timer. This timer is active during the
entire charging process. If charging has not terminated before the safety timer expires, charging is disabled, the
charge parameters are reset to the default values and the CE bit is written to a “1”. The length of the safety timer
is selectable using the I
2
C interface. A single 128μs pulse is sent on the STAT and INT outputs and the STATx
bits of the status registers are updated in the I
2
C. In DEFAULT mode, the safety timer can be reset and a new
charge initiated by removing/inserting the input supply or toggling the CD pin. In HOST mode, the CE bit is set to
a '1' when the safety timer expires. The CE bit must be cleared to a '0' in order to resume charging and clear the
safety timer fault. The safety timer duration is selectable using the TMR_X bits in the Safety Timer Register/ NTC
Monitor register. Changing the safety timer duration resets the safety timer. This function prevents continuous
charging of a defective battery.
In addition to the safety timer, the bq24160/1/1B/3 contain a watchdog timer that monitors the host through the
I
2
C interface. Once a read/write is performed on the I
2
C interface, a 30-second timer (t
WATCHDOG
) is started. The
30-second timer is reset by the host using the I
2
C interface. This is done by writing a “1” to the reset bit
(TMR_RST) in the control register. The TMR_RST bit is automatically set to “0” when the 30-second timer is
reset. This process continues until the battery is fully charged or the safety timer expires. If the 30-second timer
expires, the IC enters DEFAULT mode where the default register values are loaded, the safety timer restarts at
27 minutes and charging continues. The I
2
C may be accessed again to reinitialize the desired values and restart
the watchdog timer. The watchdog timer flow chart is shown in Figure 24.
Figure 24. The Watchdog Timer Flow Chart for bq2416x
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Product Folder Links: bq24160 bq24160A bq24161 bq24161B bq24163 bq24168