- 23 –
ViewSonic Corporation
Confidential - Do Not Copy
VX712
PIN Function
SG6841 (IC901)
:
This highly integrated PWM controllers, Low start up current 30 uA. The
circuit unit has functions such as over-current protection, over-temperature protection,
over-voltage protection, output short-circuit protection and etc. The function of each pin
and the inside circuit diagram are as follows
:
Pin/ No.
Pin
Name
Function
Pin Description
1 GND Ground
Ground.
2 FB
Feedback
The signal from external compensation circuit is feed into
this pin. The PWM duty cycle is determined by this FB pin
and current sense signal from Pin 6.
3 VIN Start-Up
This pin is pulled high to the rectified line input through a
resistor for start-up. Since the start-up current requirement
for SG6841 is very small, a large start-up resistance can
be used to minimize power loss. Under normal operation,
this pin is also used to detect line voltage to compensate
for constant output power limit for universal AC input.
4 Ri
Reference
Setting
A resistor from RI pin to ground will generate a constant
current source for SG6841. This current is used to charge
an internal capacitor and hence the switching frequency
are determined. Increasing the resistance will decrease the
current source and reduce the switching frequency,. A 26k
Ω
resistor R1 creates a 50uA constant current L1 and
generates 65kHz switching frequency.
Содержание VX712
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Страница 44: ... 44 ViewSonic Corporation Confidential Do Not Copy VX712 Sep2 Inpute the S N and execute Enter ...
Страница 45: ... 45 ViewSonic Corporation Confidential Do Not Copy VX712 ...
Страница 46: ... 46 ViewSonic Corporation Confidential Do Not Copy VX712 Sep3 Key the Enter and write the data ...
Страница 47: ... 47 ViewSonic Corporation Confidential Do Not Copy VX712 Sep4 If ddc program OK and show data compare ok ...
Страница 48: ... 48 ViewSonic Corporation Confidential Do Not Copy VX712 5 7 Packing For Shipping ...
Страница 50: ... 50 ViewSonic Corporation Confidential Do Not Copy VX712 6 Troubleshooting Flow Chart ...
Страница 69: ... 69 ViewSonic Corporation Confidential Do Not Copy VX712 9 Exploded Diagram And Spare Parts List ...
Страница 75: ... 75 ViewSonic Corporation Confidential Do Not Copy VX712 11 Block Diagram Scaler RTD2523 Include ADC OSD etc ...
Страница 81: ... 81 ViewSonic Corporation Confidential Do Not Copy VX712 12 6 Audio ...
Страница 83: ... 83 ViewSonic Corporation Confidential Do Not Copy VX712 13 3 KEYBOARD TOP VIEW 13 4 KEYBOARD BUTTON VIEW ...
Страница 84: ... 84 ViewSonic Corporation Confidential Do Not Copy VX712 13 5 POWER PCB TOP VIEW ...
Страница 85: ... 85 ViewSonic Corporation Confidential Do Not Copy VX712 13 6 POWER PCB BUTTON VIEW ...
Страница 86: ... 86 ViewSonic Corporation Confidential Do Not Copy VX712 13 7 AUDIO PCB BUTTON VIEW ...