LG GX500 Service Manual page 42

GX500 Operational Description
General Features
• Software controlled charging of Lithium-Ion batteries
• Different low power modes for very low power consumption
• Temperature monitoring with built-in over-temperature warning.
Switched Power Supplies
• Two fully integrated step-down converters with PFM low power modes:
– 400 mA high efficiency step-down converter (SD1) with 1.5 V output voltage
– 300 mA high efficiency step-down converter (SD2) with 1.8 V output voltage
• One step-up converter:
– 5.6 V ... 25 V, 120 mA step-up converter (SU1) for the main LCD backlight, keypad backlight and photo
flash.
Linear Low Dropout (LDO) Regulators
• General Purpose LDOs:
– 2.9 V, 150 mA, ultra low drop (VAUX)
– 2.62 V, 100 mA (VIO)
– 1.8 V / 2.9 V, 22 mA, ultra low drop (VSIM)
– 1.8 V / 2.9 V, 150 mA, ultra low drop (VMME)
– 2.8 V, 140 mA, ultra low drop (VVIB)
– 3.1 V, 40 mA, ultra low drop (VUSB)
• Low Noise LDOs:
– 2.5V, 220 mA (VAUDIOa)
– 2.85 V, 20 mA (VRF1)
– 1.5 V, 80 mA (VRF2)
– 2.85 V, 150 mA (VRF3)
Low Power LDOs
• 1.5 V, 20 mA (VPLL)
• 2.0 V, 4 mA (VRTC).
LED Control
• 3x PWM modulated control signal
• Current Sink Support for photo flash LED driver
• Support for serial connected LEDs
• Support for Trickle and Indicator LED.
Audio Amplifier
• Battery driven 400 mW differential audio amplifier for driving 8 ohm loudspeaker
• Three gain stages including overdrive for ringing tones
• >90 dB PSRR (4 kHz).
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