W83791G Nuvoton Technology Corporation of America, W83791G Datasheet - Page 26

• Manufacturer Part Number: W83791G
• Description: IC MONITOR H/W 48-LQFP
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83791G

• Function: Hardware Monitor
• Topology: ADC
• Sensor Type: External
• Sensing Temperature: External Sensor
• Output Type: I²C™
• Output Alarm: Yes
• Output Fan: Yes
• Voltage - Supply: 4.5 V ~ 5.5 V
• Operating Temperature: 0°C ~ 70°C
• Mounting Type: Surface Mount
• Package / Case: 48-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

6.6.1
The input voltage +12VIN can be expressed as the following equation.
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/G and the second one is that these voltages are all connected to internal serial
resistors to monitor the +5V and 5VSB voltage.
6.6.2
The negative voltage should be connected to two series resistors and a positive voltage VREF (equal
to 3.6V). In the Figure 11, the voltage V3 and V4 are two negative voltages and are -12V and -5V
respectively. The voltage V3 is connected to two serial resistors as well as another positive terminal
VREF. Therefore, the voltage node N12VIN would be a positive voltage if the scale of the two serial
resistors are carefully selected. It is recommended from Winbond that the scale of the two serial
resistors are R5=232K ohms and R6=56K ohm. The input voltage of node -12VIN can be calculated
by the following equation.
where VREF is equal to 3.6V.
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
The other negative voltage input V6 (approximate -5V) can also be evaluated by the similar method
and the serial resistors can be R7=120K ohms and R8=56K ohms by the Winbond recommended.
The expression equation of V6 With -5V voltage is shown as follows.
Where the
VREF=3.6V and the parameter
5
β
Monitor over 4.096V voltage:
Monitor negative voltage:
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.
γ
is set to 120K/ (120K+56K). If the monitored ADC value in the N5VIN channel is 0.8635,
N
12
VIN
γ
=
is 0.6818, then the negative voltage of V6 can be evaluated -5V.
(
V
VREF
V
5
6
12
=
=
VIN
N
N
12
+
5
VIN
V
VIN
=
5
V
- 20 -
)
1
1
1
×
−
×
−
−
−
(
VREF
VREF
R
232
β
γ
1
R
+
2
K
232
R
Ω
×
2
×
γ
+
K
β
Publication Release Date: April 14, 2006
Ω
56
K
Ω
)
+
V
5
W83791D/G
Revision 1.1