W83697HG Datasheet, PDF (26/109 Pages) Winbond – WINBOND LPC I/O

W83697HF/ HG
6.3.1 Monitor over 4.096V voltage:
The input voltage +12VIN can be expressed as following equation.
12VIN
=
V
1
×
R
2
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 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.
V_in
=
VCC
×
50KΩ
50KΩ + 34KΩ
≅
2.98V
where VCC is set to 5V.
The Pin 61 is connected to 5VSB voltage. W83697HF 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.
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 9.2, 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 another
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 ohms and R4=56K ohm. The input voltage of node
N12VIN can be calculated by following equation.
N12VIN
=
(VREF
+
V
2
)
×
232 KΩ
( _{232KΩ + 56KΩ})
+
V
2
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.
V₂
=
N12VIN − VREF × β
1− β
Where β is 232K/(232K+56K). If the N2VIN is 0.567 then the V2 is approximately equal to -12V.
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Publication Release Date: May 30, 2005
Revision A1