Microchip Technology MCP402XEV Manual De Usuario
MCP401X/2X Evaluation Board User’s Guide
DS51546B-page 8
© 2005 Microchip Technology Inc.
2.2.1
Evaluating the MCP4021 and MCP4011
The MCP4021/11-XXXI/SN is an 8-pin digital potentiometer device with terminals A, B
and W available on the device pins. Footprint U1 supports the 150 mil SOIC package.
Resistors R2 and R3 are 2.5 k
and W available on the device pins. Footprint U1 supports the 150 mil SOIC package.
Resistors R2 and R3 are 2.5 k
Ω
on the populated PCB, along with the 10 k
Ω
MCP4021-103I/SN digital potentiometer. This creates a “windowed” voltage divider
with a transfer function illustrated in Equation 2-1.
with a transfer function illustrated in Equation 2-1.
EQUATION 2-1:
WINDOWED POTENTIOMETER – VOLTAGE DIVIDER
CALCULATION
CALCULATION
2.2.2
Evaluating the MCP4022 and MCP4012
The MCP4022/12-XXXI/OT is a 6-pin, stand-alone digital rheostat with terminals A and
W available on the device pins. Footprint U2 supports the SOT-23-6 package. An
“INCR” command moves the wiper toward terminal A, thus causing the resistance
across the rheostat to decrease. A “DECR” command moves the wiper toward terminal
B, thus causing the resistance across the rheostat to increase.
W available on the device pins. Footprint U2 supports the SOT-23-6 package. An
“INCR” command moves the wiper toward terminal A, thus causing the resistance
across the rheostat to decrease. A “DECR” command moves the wiper toward terminal
B, thus causing the resistance across the rheostat to increase.
V
wiper
V
DD
R
wb
R3
+
(
)
⋅
R2
R3
R
nom
+
+
-------------------------------------------
5.0V
d 10k
⋅
(
)
63
⁄
2.5k
+
(
)
⋅
2.5k
2.5k
10k
+
+
---------------------------------------------------------------------
=
=
Where:
d = the wiper setting (0 to 63)
Note 1:
DO NOT populate U2 if using U1.
2:
The MCP4011 has high-voltage tolerant pins and, therefore, accepts
high-voltage Increment and Decrement commands. Since this device is
nonvolatile, the WiperLock™ Technology feature is not present.
high-voltage Increment and Decrement commands. Since this device is
nonvolatile, the WiperLock™ Technology feature is not present.
Note 1:
DO NOT populate U1 if using U2.
2:
The included MCP4021 digital potentiometer samples could be used to
evaluate the MCP4022 simply by not populating R3 and letting terminal
B float.
evaluate the MCP4022 simply by not populating R3 and letting terminal
B float.
3:
The MCP4012 has high-voltage tolerant pins and, therefore, accepts
high-voltage Increment and Decrement commands. Since this device is
nonvolatile, the WiperLock™ Technology feature is not present.
high-voltage Increment and Decrement commands. Since this device is
nonvolatile, the WiperLock™ Technology feature is not present.