W83783S_07 WINBOND [Winbond], W83783S_07 Datasheet - Page 16

• Manufacturer Part Number: W83783S_07
• Description: Winbond H/W Monitoring IC
• Manufacturer: WINBOND [Winbond]

6.3.2 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 11, the voltage V3 and V4 are two negative voltages which they are -12V and -
5V respectively. The voltage V3 is connected to two serial resistors then is connected to another
terminal VREF which is positive voltage. So the voltage node N12VIN can obtain a positive voltage if
the scales of the two serial resistors are carefully selected. It is recommended from Winbond that the
scale of two serial resistors are R5=232K ohms and R6=56K ohm. The input voltage of node -12VIN
can be calculated by following equation.
If the V
to 35h by the 8-bit ADC with 16mV-LSB.This monitored value should be converted to the real negative
voltage and the express equation is shown as follows.
Where
Another negative voltage input V6 (approximate -5V) also can be evaluated by the similar method and
the serial resistors can be selected with R7=120K ohms and R8=56K ohms by the Winbond
recommended. The expression equation of V6 With -5V voltage is shown as follows.
VREF=3.6V and the parameter
5V.
β
is set to be 120K / (120K+56K). If the monitored ADC value in the N5VIN channel is 0.8635,
5
β
is equal to -12V then the voltage is equal to 0.567V and the converted hexdecimal data is set
is 232K/(232K+56K). If the N2VIN is 0.567 then the V5 is approximately equal to -12V.
N VIN
12
β
=
is 0.6818 then the negative voltage of V6 can be evaluated to be -
(
V
VREF
V
where VREF is equal 3.6V.
5
6
=
=
N VIN
N VIN
12
+
5
V
5
) (
- 12 -
1
1
×
−
−
−
−
VREF
VREF
232
γ
β
K
232
Ω
×
×
Publication Release Date: August 21, 2007
+
γ
K
β
Ω
56
K
Ω
)
+
V
5
W83783S
Revision 1.0