13892 datasheet(61/158 Pages) FREESCALE

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FUNCTIONAL DEVICE OPERATION

OPERATING MODES

Analog Integrated Circuit Device Data



Freescale Semiconductor

MC13892

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 Datasheet(PDF) 61 Page - Freescale Semiconductor, Inc

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