Page 62 - GIGABYTE Service Manual-v3.0-110101

3.2.7 VCC_PLL1

VCC_PLL1 circuit is separated into 4 sections:
MOSFET

Low Power Quad Operational Amplifiers
Feedback circuit
Over Voltage Controller

Figure 3-16: VCC_PLL1
MOSFET Section:
The section Includes Q16 and R, C. The output VCC_PLL1 (1.5V) depends on input

VCC3 and control gate which input from U18. If control gate fail, we can measure the
voltage across resistor R106 to confirm any resistor broken or U18 pin14 fail. Also
need to measure impedance on pin 1 of Q16.
Low Power Quad Operational Amplifiers Section:
The section Includes U18 and R, C. The output pin 14 depends on pin 12,13 which

pin 12 input from VCC_PLL1_EN and divided voltage of 2_5LEVEL, and pin 13
feedback circuit , over voltage circuit VCC_PLL1_OV.
Feedback circuit Section:

The section Includes R471, R459 and C257, EC7. For the feedback pin 13, we can read
a voltage of 1.5V. This pin also connects to VCC_PLL1_OV for over voltage from
U10.
Over Voltage Controller Section:
The section Includes U10 which is three voltage channel console, the uP6262 is a high

precision voltage console consisting of three sets I2C programmable current DACs.

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