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Only for training and service purposes
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3. TECHNICAL BRIEF
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3.10 Power Block
3.10.1. General
MSM7227, included RF, is fully covered by PM7540 (Qualcomm PMIC). PM7540 cover the power of MSM7227,
MSM memory, RF block, Bluetooth, USIM and TCXO.
Major power components are :
PM7540 (U403) : Phone main PMIC
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-wire SBI(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.
