FUNCTIONAL DEVICE OPERATION
OPERATING MODES
Charger Attach
CHRGRAW is pulled high with corresponding interrupt and sense bits CHGDETI and CHGDETS. This is equivalent to
plugging in a charger. BP should be above BPON. The charger turn on event is dependent on the charge mode selected. For
details on the charger detection and turn on, see Battery Interface and Control.
Battery Attach
BP crossing the BPON threshold which corresponds to attaching a charged battery to the product. A corresponding BPONI
interrupt is generated, which can be cleared by software or when cycling through the Off mode. Note that BPONI is also
generated after a successful power cut and potentially when applying a charger.
USB Attach
VBUS pulled high with corresponding interrupt and sense bits BVALIDI and BVALIDS. This is equivalent to plugging in a USB
cable. BP should be above BPON and the battery voltage above BATTON. For details on the USB detection, see Connectivity.
RTC Alarm
TOD and DAY become equal to the alarm setting programmed. This allows powering up a product at a preset time. BP should
be above BPON. For details and related interrupts, see Clock Generation and Real Time Clock.
System Restart
System restart may occur after a system reset. This is an optional function, see also the following Turn Off events section. BP
should be above BPON.
TURN OFF EVENTS
Power Button Press
User shut down of a product is typically done by pressing the power button connected to the PWRONx pin. This will generate
an interrupt (PWRONxI), but will not directly power off the part. The product is powered off by the processor's response to this
interrupt, which will be to pull WDI low. Pressing the power button is therefore under normal circumstances not considered as a
turn off event for the state machine.
Note that software can configure a user initiated power down via a power button press for transition to a low power off mode
(Memory Hold or User Off) for a quicker restart than the default transition into the Off state.
Power Button System Reset
A secondary application of the PWRON pin is the option to generate a system reset. This is recognized as a Turn Off event.
By default, the system reset function is disabled but can be enabled by setting the PWRONxRSTEN bits. When enabled, a 4
second long press on the power button will cause the device to go to the Off mode and as a result the entire application will power
down. An SYSRSTI interrupt is generated upon the next power up. Alternatively, the system can be configured to restart
automatically by setting the RESTARTEN bit.
Thermal Protection
If the die gets overheated, the thermal protection will power off the part to avoid damage. A Turn On event will not be accepted
while the thermal protection is still being tripped. The part will remain in Off mode until cooling sufficiently to accept a Turn On
event. There are no specific interrupts related to this other than the warning interrupts.
Under-Voltage Detection
When the voltage at BP drops below the under-voltage detection threshold UVDET, the state machine will transition to Off
mode if PCUT is not enabled, or if the PCT timer expires when PCUT is enabled.
TIMERS
The different timers as used by the state machine are in Table 25. This listing does not include RTC timers for timekeeping.
A synchronization error of up to one clock period may occur with respect to the occurrence of an asynchronous event. The
duration listed below is therefore the effective minimum time period.
13892
Analog Integrated Circuit Device Data
Freescale Semiconductor
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FREESCALE [ Freescale ]
