Motorola D10 Service Manual page 65

BenQ
3.4 System power on/off Sequence
3.4.1 Power on
There are three conditions that system can power on.
-On button pushed: a falling edge is detected on PWON pin and the
-Set Alarm: a rising edge is detected on RTC_ALARM (RTCINT)
-Charger plugged: VCHG > VBAT + 0.4V is detected
When these conditions occur in the power on state, the hardware
power on sequence starts:
1. Enable local oscillator OSCAS (~ 100KHz)
2. Enable band-gap (VREF and IREF)
3. Check if Main Battery voltage is greater than 3.2V
4. Enable charge pump (VAUX ~ 5.8V)
5. Enable LDO regulators (R1, R1B, R2, R2B and R3)
6. Set ON_OFF pin to 'H'.
7. NRESET pin is set from 'L' to 'H'
8. 13MHz clock oscillator is enabled (Ulysse's task)
3.4.2 Power off in normal mode
When system is powered off in normal mode by long pressing
power-on key, the power off sequence will be executed:
1. Start watchdog timer during 150us and disable DC/DC
2. Set ON_OFF pin to 'L'
3. Disable all the regulators
4. Disable the band-gap
5. Disable the local oscillator OSCAS
3.4.3 Power off in emergency mode
When the main battery voltage is detected lower than 2.7V, the
following sequence is executed:
1. Set INT1 (FIQ) to 'L'
2. Start watchdog timer during 150us and disable DC/DC
3. Set ON_OFF pin to 'L'
4. Disable all the regulators
5. Disable the band-gap
6. Disable the local oscillator OSCAS
debouncing time is greater than 30ms.
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