W83697HF/F
9.3 Analog Inputs
The maximum input voltage of the analog pin is 4.096V because the 8-bit ADC has a 16mv LSB. Really,
the application of the PC monitoring would most often be connected to power suppliers. The CPU V-core
voltage ,+3.3V ,battery and 5VSB voltage can directly connected to these analog inputs. The +12V,-12V
and -5V voltage inputs should be reduced a factor with external resistors so as to obtain the input range.
As Figure 9.2 shows.
Pin 100
VCOREA
Pin 99
VCOREB
Positive Inputs
Pin 98
Pin 97
Pin 74
Pin 61
+3.3VIN
AVCC(+5V)
VBAT
5VSB
R1
+12VIN
Pin 96
V1
8-bit ADC
with
16mV LSB
Positive Input
Negative Input
R2
R3
N12VIN
N5VIN
Pin 95
Pin 94
V2
V3
R5
R6
R4
R
10K, 1%
VREF
Pin 101
VTIN3
Pin 102
Pin 103
Pin 104
Typical Thermister Connection
VTIN2
VTIN1
R
THM
10K, 25 C
**The Connections of VTIN1 and VTIN2
are same as VTIN3
Figure. 9.2
9.3.1 Monitor over 4.096V voltage:
The input voltage +12VIN can be expressed as following equation.
R 2
1 2 V I N = V1 ´
R1
R
2
+
The value of R1 and R2 can be selected to 28K Ohms and 10K Ohms, respectively, when the input
voltage V1 is 12V. The node voltage of +12VIN can be subject to less than 4.096V for the maximun input
range of the 8-bit ADC. The Pin 97 is connected to the power supply VCC with +5V. There are two
functions in this pin with 5V. The first function is to supply internal analog power in the W83697HF and
the second function is that this voltage with 5V is connected to internal serial resistors to monitor the
+5V voltage. The value of two serial resistors are 34K ohms and 50K ohms so that input voltage to ADC
is 2.98V which is less than 4.096V of ADC maximum input voltage. The express equation can represent
as follows.
Publication Release Date: Feb. 2002
- 85 -
Revision 0.70
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