W83627HF Datasheet, PDF (112/185 Pages) Winbond – WINBOND I/O

W83627HF/F
PRELIMINARY
V_in
=
VCC
×
50KΩ
50KΩ + 34KΩ
≅
2.98V
where VCC is set to 5V.
The Pin 61 is connected to 5VSB voltage. W83627HF 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.
11.3.2 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 11.2, 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
+
V₂
)
×
( ^232KΩ )
232KΩ + 56KΩ
+ V₂
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
1− β
×β
Where β is 232K/(232K+56K). If the N2VIN is 0.567 then the V2 is approximately equal to -12V.
The another negative voltage input V3 (approximate -5V) also can be evaluated by the similar
method and the serial resistors can be selected with R5=120K ohms and R6=56K ohms by the
Winbond recommended. The expression equation of V3 With -5V voltage is shown as follows.
V₃
=
N 5VIN − VREF
1−γ
×γ
Where the γ is set to 120K/(120K+56K). If the monitored ADC value in the N5VIN channel is 0.8635,
VREF=3.6V and the parameter γ is 0.6818 then the negative voltage of V3 can be evalated to be -5V.
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Publication Release Date: Jul 1999
Revision 0.53