Power Block - LG E900 Service Manual

3.9 Power Block

3.9.1 General
QSD8650 is covered by PM7540(Qualcomm PMIC) and TPS65023 (TI BUCK).
PM7540 cover the power of QSD8650, memory, RF block(RTR6280), USIM and TCXO.
Major power components are :
PM7540(U405) : Phone main PMIC
TPS65023(U401) : Core voltage source
AAT2862(U508) : LCD BLT Charge Pump
LM2759(U704) : Camera Flash driver
NUS5530(Q400) : main power path switch( battery charging circuit)
MAX14528(U404) : OVP( Over voltage protection) IC
3.9.2 PM7540
The PM7540 device (Figure) integrates all wireless handset power management. The power
management portion accepts power from all the most common sources – battery, external charger,
adapter, coin cell back-up – and generates all the regulated voltages needed to power the
appropriate handset electronics. It monitors and controls the power sources, detecting which
sources are applied, verifying that they are within acceptable operational limits, and coordinates
battery and coin cell recharging while maintaining the handset electronics supply voltages. Eight
programmable output voltages are generated using low dropout voltage regulators, all derived from
a common trimmed voltage reference.
A dedicated controller manages the TCXO warm-up and signal buffering, and key parameters (under-
voltage lockout and crystal oscillator signal presence) are monitored to protect against detrimental
conditions.
QSD8650 device controls and statuses the PM7540 IC using Single Serial Bus Interface (SSBI)
supplemented by an Interrupt Manager for time-critical information. Another dedicated IC Interface
circuit monitors multiple trigger events and controls the power-on sequence.
Copyright © 2010 LG Electronics. Inc. All right reserved.
Only for training and service purposes
- 41 -
3. TECHNICAL BRIEF
LGE Internal Use Only