LG HB620 Service Manual page 28

■ 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)
■ Integrated handset-level user interfaces
- Four programmable current sinks recommended as keypad backlight, LCD backlight, camera
flash, and general-purpose drivers
- Vibration motor driver programmable from 1.2 to 3.1V in 100 mV increments
- Speaker driver with programmable gain, turn-on time, and muting; differential operation (drives
external 8 Ω speakers with volume controlled 500 mW)
Copyright © 2008 LG Electronics. Inc. All right reserved.
Only for training and service purposes
3. TECHNICAL BRIEF
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LGE Internal Use Only