Dell 1909Wf, Service Manual, Page: 24 / 71

Service Manual
23
8.3 U850 (LD7575, Power Controller)
Pin Symbol I/O Description
1 RT This pin is to program the switching
frequency
2 COMP
I Voltage feedback pin,By connecting a
photo-coupler to close the control loop
and achieve the regulation
3 CS I Current sence pin
4 GND
5 OUT
O PWM output ,Gate drive output to drive
the external MOSFET
6 VCC I Power supply
7 NC Unconnected pin
8 HV I PWM output
8.4 U1 ( INL836, CCFL Inverter controller IC)
Pin Symbol I/O Description
1 SST_CMP I Enable, soft start time and
compensation of current error amplifier
2 RT I Timing capacitor to set operating
frequency
3 GNDA Ground
4 DRV2 O N MOSFET Driver output
5 DRV1 O N MOSFET Driver output
6 VDDA I Supply voltage input
7 VSEN_DIM I Voltage sense, input analog signal for
PWM driving control
8 ISEN I Lamp current detection & control