Sanyo VPC-J4 Service Manual

Contents

– 4 –1-3. ST1 POWER CIRCUIT DESCRIPTION1. OutlineThis is the main power circuit, and is comprised of the follow-ing blocks.Switching power controller (IC501)Analog system power output (Q5001, T5001)Digital 1.8 V power output (L5006)Digital 3.3 V power output (L5005)LCD 15 V power output (Q5015, L5007)LED backlight power output (Q5003, L5009)5 V system power output (L5004)4.7 V lens system power output (IC955, Q9552, L9551)2. Switching ControllerThis is the basic circuit which is necessary for controlling thepower supply for a PWM-type switching regulator, and is pro-vided with five built-in channels, only CH1 (analog systempower output), CH2 (LCD 15 V power output), CH_M (digital3.3 V system power output), CH_SD (digital 1.8 V systempower output), CH3 (LED back light power output) and CH_SU(5 V system power output) are used. Feedback from 15.0 V(A) (CH1), 15 V (L) (CH2), 3.3 V (D) (CH_M), 1.8 V (D)(CH_SD), LED backlight output (CH3) and 5 V (CH_SU) powersupply outputs are received, and the PWM duty is varied sothat each one is maintained at the correct voltage setting level.2-1. Short-circuit ProtectionIf output is short-circuited for the length of time setting insideIC501, all output is turned off. The control signal (P ON) arerecontrolled to restore output.3. Analog System Power Output15.0 V (A), -7.6 V (A) and 3.45 V (A) are output. Feedback forthe 15.0 V (A) is provided to the switching controller (Pin (3)of IC501) so that PWM control can be carried out.4. Digital 1.8 V Power Output1.8 V (D) is output. Feedback for the 1.8 V (D) is provided tothe switching controller (Pins (9) of IC501) so that PWM con-trol can be carried out.5. Digital 3.3 V Power Output3.3 V (D) is output. Feedback for the 3.3 V (D) is provided tothe swiching controller (Pin (13) of IC501) so that PWM con-trol can be carried out.6. LCD 15 V Power OutputLCD 15 V (L) is output. Feedback for the 15 V (L) is providedto the swiching controller (Pin (31) of IC501) so that PWMcontrol can be carried out.7. LED Backlight Power OutputA constant current flows to LCD 8.5 V (L) power and the back-light LEDs. Feedback for the voltage of R5047 and R5048are provided to the power controller (Pin (39) of IC501) sothat PWM control can be carried out.8. 5 V System Power Output5 V is output. Feedback for the 5 V is provided to the swichingcontroller (Pin (17) of IC501) so that PWM control can becarried out.9. 4.7 V Lens System Power OutputLens power (4.7 V) is output. Feedback for the BOOST 4.7 Vis provided to the swiching controller (Pin (1) of IC955) sothat PWM control can be carried out.