Power Block - LG GM750 Service Manual

3. Technical Brief

3.10. Power Block

3.10.1. General
MSM7200A, included RF, is fully covered by PM7540(Qualcomm PMIC). PM7540 cover the
power of MSM7200A, MSM memory, RF block, Bluetooth, USIM and TCXO.
Major power components are :
PM7540(U403) : Phone power supply
BD6083GUL(Sub-pcb:U502) : LCD Backlight charge pump
3.10.2 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.
MSM 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.
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