LG U250, Service Manual

Page: 26 / 175

3. TECHNICAL BRIEF
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3.5.4 PMIC Functional Block Diagram (U300 : PM6650-2M)
• Input power management
- Valid external supply attachment and removal detection
- Supports unregulated (closed-loop) external charger supplies and USB supplies as input power
sources
- Supports lithium-ion main batteries
- Trickle, constant current, constant voltage, and pulsed charging of the main battery
- Supports coin cell backup battery (including charging)
- Battery voltage detectors with programmable thresholds
- VDD collapse protection
- Charger current regulation and real-time monitoring for over-current protection
- Charger transistor protection by power limit control
- Control drivers for two external pass transistors and one external battery MOSFET - MOSFET is
optional
- Voltage, current, and power control loops
- Automated recovery from sudden momentary power loss
• Output voltage regulation
- One boost (step-up) switched-mode power supply (SMPS) for driving white LEDs and hosting
USBOTG
- Three buck (step-down) switched-mode power supplies that efficiently generate MSMC, MSME,
and PA (or second MSMC) supply voltages
- Supports dynamic voltage scaling (DVS) for MSMC and PA
- Eleven low dropout regulator circuits with programmable output voltages, implemented using three
different current ratings: 300 mA (two), 150 mA (six), and 50 mA (three). These can be used to
power MSMA, MSMP, RFRX1, RFRX2, RFTX, SYNT, TCXO, WLAN, MMC, USB, and RUIM
circuits.
- All regulators can be individually enabled/disabled for power savings
- Low power mode available on MSMA and MSMP regulators
- All regulated outputs are derived from a common bandgap reference-close tracking
• Integrated handset-level housekeeping functions reduces external parts count, size, cost
- Analog multiplexer selects from 8 internal and up to 18 external inputs
- Multiplexer output’s offset and gain are adjusted, increasing the effective ADC resolution
- Adjusted multiplexer output is buffered and routed to an MSM device ADC
- Dual oscillators - 32.768 kHz off-chip crystal and on-chip RC assures MSM device sleep clock
- Crystal oscillator detector and automated switch-over upon lost oscillation
- Real time clock for tracking time and generating associated alarms
- On-chip adjustments minimize crystal oscillator frequency errors
- Circuits control TCXO warm-up and synchronize, deglitch, and buffer the TCXO signal
- TCXO buffer control for optimal QPH/catnap timing
- Three-stage over-temperature protection (smart thermal control)