Power Block - LG KS20 Operating Instructions Manual

3. TECHNICAL BRIEF

3.9. Power Block

3.9.1. General
MSM7200, included RF, is fully covered by PM7540(Qualcomm PMIC). PM7540 cover the power of
MSM7200, MSM memory, RF block, Bluetooth, USIM and TCXO. Major power components are :
PM7540(U304) : Phone power supply
MAX8645Y(U702) : LCD Backlight/Flash charge pump
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.
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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