W83627UHG Nuvoton Technology Corporation of America, W83627UHG Datasheet - Page 43

• Manufacturer Part Number: W83627UHG
• Description: IC I/O CONTROLLER 128-QFP
• Manufacturer: Nuvoton Technology Corporation of America

Specifications of W83627UHG

• Applications: PC's, PDA's
• Interface: LPC
• Voltage - Supply: 3.3V, 5V
• Package / Case: 128-XFQFN
• Mounting Type: Surface Mount
• Pin Count: 128
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

7.3.1
Input voltages greater than 2.048 V should be reduced by an external resistor divider to keep the input
voltages in the proper range. For example, input voltage V
connected to VIN0 according to the following equation:
R1 and R2 can be set to 150 KΩ and 10 KΩ, respectively, to reduce V
V.
The W83627UHG uses the same approach. Pins 12 and 97 provide two functions. One, these pins
are connected to 5VCC at +5 V to supply internal (digital / analog) power to the W83627UHG. Two,
these pins monitor 5VCC. The W83627UHG has two internal, 80-KΩ and 20-KΩ, serial resistors that
reduce the ADC-input voltage to 1 V.
Pin 61 is implemented likewise to monitor its +5 V stand-by power supply.
Pin 74 also has two internal, 20-KΩ serial resistors that reduce the ADC-input voltage to 1.65 V.
The CPUVCORE pin feeds directly into the ADC with no voltage divider since the nominal voltage on
this pin is only 1.2V.
Negative voltages are handled similarly, though the equation looks a little more complicated. For
example, negative voltage V2 (-5V) can be reduced according to the following equation:
R3 and R4 can be set to 120 KΩ and 10 KΩ, respectively, to reduce negative input voltage V
V to less than 2.048 V. Note that R4 is referenced to VREF, or 2.048V instead of 0V to allow for more
dynamic range. This is simply good analog practice to yield the most precise measurements.
Both of these solutions are illustrated in the figure above.
7.3.2
The data format for voltage detection is an eight-bit value, and each unit represents an interval of 8
mV.
up accordingly.
If the source voltage was reduced by a voltage divider, the detected voltage value must be scaled
Voltages Over 2.048 V or Less Than 0 V
Voltage Detection
V
in
V
=
VIN
in
VBAT
=
2
5
VCC
=
(
V
×
20
2
Detected Voltage = Reading * 0.008 V
×
−
80
K
. 2
20
Ω
K
048
+
20
Ω
K
VIN
20
Ω
+
K
)
×
20
0
Ω
K
R
Ω
=
K
3
V
R
Ω
≅
-32-
+
0
4
. 1
R
×
≅
65
4
R
1
V
1
+
V
R
+
. 2
, where 5VCC is set to 5V
0
2
, where VBAT is set to 3.3V
R
(+12 V) should be reduced before it is
048
2
,
whereV
0
from +12 V to less than 2.048
2
=
W83627UHG
−
5
2
from – 5