Only For Training And Service Purposes - LG GM200 Service Manual

3.2.2 Power ON/OFF
CSPORT interface, power management control interface and the circuit that generates
power up RESET pulses (RESET2P8 and RESET1P8) for use by the DBB chip.
All regulators except the USB interface regulator are powered from the main battery.
The USB regulator is powered from USB VBUS.
And the user presses KEYON which puts the AD6725-ATLAS3HLITE power management system into
ACTIVATION state (see definitions below) and signals DBB software that it's time to wake up and operate
using the KEYOUT signal. RPWROM is using for booting up though PIF.
D 1 0 6
1
P W R O N
2
R P W R O N
K D R 3 3
3.2.3Power On Reset Generator
The power-on reset signals (RESET1P8 and RESET2P8) are asserted based on the VCORE (if VAPPCFG = 0),
VMEM, VEXT, and VPLL regulators. RESET1P8 and RESET2P8 are low when reset is enabled and high when
reset is disabled.
When the outputs of all four regulators reach their corresponding threshold voltages, reset will be disabled
after a nominal reset period of 130ms.
The outputs of all four regulators must remain at or above their corresponding threshold voltages for the
duration of the reset period for reset to be disabled (pulled high).
The nominal 130ms reset period is restarted whenever all four regulators reach their threshold voltages. The
nominal reset period of 130ms can be extended by connecting an external capacitor to CRST. This capacitor
is charged using a small current when reset is enabled. Once the capacitor reaches the threshold, reset is
disabled.
Reset will be enabled immediately if any one of the four regulators falls below their corresponding threshold
voltages. In addition, reset will be enabled if VBAT falls below VRTC. The PWREN signal is the logical AND of
all the state controls that enable or disable many of the regulators on the chip. If the regulators enabled by
PWREN are
disabled by PMT state controls described below then PWREN must go low.
When PWREN goes low reset will be immediately enabled causing RESET1P8 and RESET2P8 to be pulled low.
When reset is enabled, both RESET1P8 and RESET2P8 are actively pulled low.
CRST is also actively pulled low when reset is enabled.
LGE Internal Use Only
Copyright © 2009 LG Electronics. Inc. All right reserved.

Only for training and service purposes

3
D B B O N
P
R 1 3 0
1 V
4 7 K
Figure. 3-2-4 GM200 power on/off circuit diagram
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O W E R K E Y
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3. TECHNICAL BRIEF
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1 1 6
5 0
LGE Internal Use Only