W83627HF/ F/ HG/ G
50KΩ
50KΩ + 34KΩ
V = VCC ×
≅ 2.98V
in
where VCC is set to 5V.
The Pin 61 is connected to 5VSB voltage. W83627HF monitors this voltage and the internal two serial
resistors are 17K Ω and 33K Ω so that input voltage to ADC is 3.3V which less than 4.096V of ADC
maximum input voltage.
7.3.2 Monitor negative voltage：
The negative voltage should be connected two series resistors and a positive voltage VREF （is
equal to 3.6V）. In the Figure 8.2, the voltage V2 and V3 are two negative voltage which they are -
12V and -5V respectively. The voltage V2 is connected to two serial resistors then is connected to an-
other terminal VREF which is positive voltage. So as that the voltage node N12VIN can be obtain a
posedge voltage if the scales of the two serial resirtors are carefully selected. It is recommanded from
Winbond that the scale of two serial resistors are R3=232K ohm and R4=56K ohm. The input voltage
of node N12VIN can be calculated by following equation.
232KΩ
232KΩ + 56KΩ
N12VIN = (VREF + V2 ) × (
) +V2
Where VREF is equal 3.6V.
If the V2 is equal to -12V then the voltage is equal to 0.567V and the converted hexdecimal data is set
to 35h by the 8-bit ADC with 16mV-LSB.This monitored value should be converted to the real negative
votage and the express equation is shown as follows.
N12VIN −VREF × β
V2 =
1− β
Where β is 232K/（232K+56K）. If the N2VIN is 0.567 then the V2 is approximately equal to -12V.
The another negative voltage input V3 （approximate -5V） also can be evaluated by the similar
method and the serial resistors can be selected with R5=120K ohms and R6=56K ohms by the Win-
bond recommended. The expression equation of V3 With -5V voltage is shown as follows.
N5VIN −VREF × γ
V3 =
1− γ
Where the γ is set to 120K/（120K+56K）. If the monitored ADC value in the N5VIN channel is
0.8635, VREF is 3.6V and the parameter γ is 0.6818 then the negative voltage of V3 can be evalated
to be -5V.
Publication Release Date: June 09, 2006
- 33 -
Revision 2.27
WINBOND [ WINBOND ]
