MCP4013 Microchip Technology, MCP4013 Datasheet - Page 27

• Manufacturer Part Number: MCP4013
• Description: Low-Cost 64-Step Volatile Digital POT
• Manufacturer: Microchip Technology

4.0
The MCP4011/2/3/4 devices are general purpose
digital potentiometers intended to be used in
applications where a programmable resistance with
moderate bandwidth is desired.
Applications generally suited for the MCP4011/2/3/4
devices include:
• Set point or offset trimming
• Sensor calibration
• Selectable gain and offset amplifier designs
• Cost-sensitive mechanical trim pot replacement
The digital potentiometer is available in four nominal
resistances (R
defined as the resistance between terminal A and
terminal B. The four nominal resistances are 2.1 kΩ,
5 kΩ, 10 kΩ and 50 kΩ.
There are 63 resistors in a string between terminal A
and terminal B. The wiper can be set to tap onto any of
these 63 resistors thus providing 64 possible settings
(including terminal A and terminal B).
Figure 4-1
network of the device.
calculation for the step resistance, while
illustrates the calculation used to determine the
resistance between the wiper and terminal B.
FIGURE 4-1:
© 2006 Microchip Technology Inc.
R
R
R
R
Note 1: The wiper resistance is tap dependent.
S
S
S
S
GENERAL OVERVIEW
A
B
shows a block diagram for the resistive
N = 63
N = 62
N = 61
N = 1
N = 0
That is, each tap selection resistance
has a small variation. This variation
effects the smaller resistance devices
(2.1 kΩ) more.
AB
), where the nominal resistance is
R
R
R
R
R
W
W
W
W
W
Resistor Block Diagram.
(1)
(1)
(1)
(1)
(1)
3Eh
3Fh
3Dh
01h
00h
Equation 4-1
Analog
Mux
Equation 4-2
shows the
W
EQUATION 4-1:
EQUATION 4-2:
1 LSb is the ideal resistance difference between two
successive codes. If we use N = 1 and R
Equation
increment or decrement command.
The MCP4011 device offers a voltage divider
(potentiometer) with all terminals available on pins.
The MCP4012 is a true rheostat, with terminal A and
the wiper (W) of the variable resistor available on pins.
The MCP4013 device offers a voltage divider (potenti-
ometer) with terminal B connected to ground.
The MCP4014 device is a Rheostat device with
terminal A of the resistor floating, terminal B connected
to ground, and the wiper (W) available on pin.
The MCP4011 can be externally configured to
implement any of the MCP4012, MCP4013 or
MCP4014 configurations.
4.1
A 2-wire synchronous serial protocol is used to
increment or decrement the digital potentiometer’s
wiper terminal. The Increment/Decrement (U/D)
protocol utilizes the CS and U/D input pins. Both inputs
are tolerant of signals up to 12.5V without damaging
the device. The CS pin can differenciate between two
high-voltage levels, V
additional commands without requiring additional input
pins. The high-voltage commands (V
are similar to the standard commands and are
supported for compatability to the MCP401X family of
devices.
The simple U/D protocol uses the state of the U/D pin
at the falling edge of the CS pin to determine if
Increment or Decrement mode is desired. Subsequent
rising edges of the U/D pin move the wiper.
The wiper value will not underflow or overflow.
Serial Interface
4-2, we can calculate the step size for each
MCP4011/2/3/4
N = 0 to 63 (decimal)
R
R
WB
S
=
R
R
=
IH
S
WB
R
---------
63
R
------------- -
AB
CALCULATION
AB
63
and V
CALCULATION
N
+
R
IHH
W
IHH
DS21978C-page 27
. This enables
on the CS pin)
W
= 0 in