Service Manual
19
8.3 U850 (LD7552B, PWM Power Controller)
Pin Symbol I/O Description
1 GND Ground
2 COMP I Voltage feedback pin,by connecting a photo-coupler
to close the control loop and achieve the regulation
3 VCC I Supply voltage pin
4 RT I This pin is to program the switching frequency. By
connecting a resistor to ground to set the switching
frequency.
5 NC Unconnected pin
6 CS I Current sense pin,connect to sense the MOSFET
current.
7 VCC I Supply voltage pin
8 Out O Gate drive output to drive the external MOSFET
8.4 U1 (INL833, CCFL Inverter controller IC)
Pin Symbol I/O Description
1 VSEN I Voltage Sense Feedback
2 SSTCMP I Capacitor for Soft-Start and loop Compensation
3 CT I Timing Resistor and Capacitor for Operation and
Striking Frequency
4 RT I Timing Resistor for Striking Frequency
5 GNDA Signal Ground
6 PDR2 O High Side Driver Output2
7 GNDP Power Ground
8 NDR2 O Low Side Driver Output2
9 NDR1 O Low Side Driver Output1
10 PDR1 O High Side Driver Output1
11 VDDA I Input Power Pin
12 TIMER I Timing Capacitor for Delay Timer
13 PWM I Ecternal PWM Dimming Input
14 ISEN I Current Sense Feedback
15 OVPT I Over-Voltage Protection Threshold Voltage
16 ENA I IC Enable/Disable
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