W83791D Datasheet, PDF (26/46 Pages) Winbond – W83791D Winbond H/W Monitoring IC

W83791D
Preliminary
6.6
Analog Inputs
The maximum input voltage of the analog pin is 4.096V because the 8-bit ADC has a 16mv LSB. Actually,
the application of the PC monitoring would most often be connected to power supply. The CPU V-core
voltage,+3.3V and battery voltage can directly connect to these analog inputs. The –5V, –12V and +12V inputs
should be reduced a factor with external resistors to meet the input range. As Figure 7 shows.
R1
V1
Positive Input
Positive Inputs
12VIN
+1.8Vcore
+1.5VINR0
+3.3VIN
VINR1
VBAT
5VSB
R2
Pin 36
Pin 35
Pin 34
Pin 33
Pin 30
Pin 32
Pin 29
8-bit ADC
with
16mV LSB
V3
Negative Input
R7
V4
Typical Thermister Connection
R5
N12VIN
Pin 31
N5VIN
Pin 28
R8
R6
R
10K, 1% _VREF
Pin 37
VTIN3
Pin 38
RTHM
10K, 25 C
VTIN2
VTIN1
Pin 39
Pin 40
**The Connections of VTIN1 and VTIN2
are same as VTIN3
Figure 7.
6.6.1 Monitor over 4.096V voltage:
The input voltage +12VIN can be expressed as the following equation.
12VIN
= V₁
×
R₂
R₁ + R₂
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 should be subject to under 4.096V for the maximum input range of the 8-bit
ADC. The pin 13 and pin 29 are discretely connected to the power supply +5V and 5VSB . There are two functions
in these pins with 5V. The first function is to supply internal analog power in the W83791D and the second one is
that these voltages are all connected to internal serial resistors to monitor the +5V and 5VSB voltage.
19
Publication Release Date: Aug, 2001
Revision 0.41