Datasheet

MCP4021/2/3/4
DS21945E-page 42 © 2006 Microchip Technology Inc.
6.0 RESISTOR
Digital potentiometer applications can be divided into
two categories:
• Rheostat configuration
• Potentiometer (or voltage divider) configuration
Figure 6-1 shows a block diagram for the MCP402X
resistors.
FIGURE 6-1: Resistor Block Diagram.
Step resistance (R
S
) is the resistance from one tap
setting to the next. This value will be dependent on the
R
AB
value that has been selected. Table 6-1 shows the
typical step resistances for each device.
The total resistance of the device has minimal variation
due to operating voltage (see Figure 2-6, Figure 2-17,
Figure 2-27 or Figure 2-37).
TABLE 6-1: TYPICAL STEP RESISTANCES
Terminal A and B, as well as the wiper W, do not have
a polarity. These terminals can support both positive
and negative current.
R
S
A
R
S
R
S
R
S
B
N = 63
N = 62
N = 61
N = 1
N = 0
R
W
(1)
W
01h
Analog
Mux
R
W
(1)
00h
R
W
(1)
3Dh
R
W
(1)
3Eh
R
W
(1)
3Fh
Note 1: The wiper resistance is tap dependent.
That is, each tap selection resistance
has a small variation. This variation
effects the smaller resistance devices
(2.1 kΩ) more.
Part Number
Typical Resistance (Ω)
Total (R
AB
) Step (R
S
)
MCP402X-203E 2100 33.33
MCP402X-503E 5000 79.37
MCP402X-104E 10000 158.73
MCP402X-504E 50000 793.65