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3. TECHNICAL BRIEF
LGE Internal Use Only
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3.5 Power ON/OFF
3.5.1 ON/OFF Switching Sequence
After the ON-trigger (either from ON_OFF1/2 pin or charger) SGR PMU Subsystem follows a well-
defined startup sequence to ensure a proper system start up.
State power supply is connected and ON is triggered: (enter point of System Startup Statem Machine)
• ON_OFF1 is low (or ON_OFF2 is high, or VCH>3.2V)
• VRTC is active
• I2C_INT is high
• On-chip oscillator calibrated and running, reference and bias calibrated and running Startup
Sequence from System Startup State Machine
• Start SD1 in active mode
• After time TE1 start SD2 in active mode
• After TDEL1 delay, start LDOs in the sequence: VRF1, VIO, VPLL, VAUX (all started with delay to
each other)
• After TE2 delay (settling of the DCXO) force signal I2C_INT to low. Comparator for VAUX voltage
supervision is enabled
• After TE3 (settling S-GOLDradio Power Management Unit GPIOs) RESET_N/RESET2_N are
released
Summary of Contents for KC550
Page 1: ...Date May 2008 Issue 1 0 Service Manual Model KC550 Service Manual KC550 Internal Use Only ...
Page 182: ...Note ...
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