MCP4011-103E/SN Microchip Technology, MCP4011-103E/SN Datasheet - Page 12

• Manufacturer Part Number: MCP4011-103E/SN
• Description: IC DGTL POT 10K 1CH 8SOIC
• Manufacturer: Microchip Technology

Specifications of MCP4011-103E/SN

• Package / Case: 8-SOIC (3.9mm Width)
• Taps: 64
• Resistance (ohms): 10K
• Number Of Circuits: 1
• Temperature Coefficient: 150 ppm/°C Typical
• Memory Type: Volatile
• Interface: Up/Down
• Voltage - Supply: 1.8 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Resistance In Ohms: 10K
• Number Of Pots: Single
• Taps Per Pot: 64
• Resistance: 10 KOhms
• Wiper Memory: Volatile
• Digital Interface: Serial (2-Wire)
• Operating Supply Voltage: 2.5 V or 3.3 V or 5 V
• Supply Current: 0.045 mA (Typ)
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: - 40 C
• Mounting Style: SMD/SMT
• Supply Voltage (max): 5.5 V
• Supply Voltage (min): 1.8 V
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

In the following circuit, a resistor ladder is used to create
a voltage window where Pot1 is used to trim the desired
offset for the band pass filter. This resistor ladder setting
also works with capacitor C2 to set the high pass filter
frequency.
A second potentiometer (Pot2) is used in a rheostat mode
along with R3 and R4 to control the gain of the amplifier.
The step resistance of Pot2 relative to resistors R3 and R4
determines if the gain trimming is a fine adjustment or a
course adjustment. Capacitor C1 along with Pot2, R3 and
R4 is used to set the low pass filter.
Capacitor C1 is also used for compensation of the Op Amp
and to inhibit the output from oscillating.
If capacitor C1 is not present, then the circuit is a high
pass filter, while if capacitor C2 is not present then the
circuit is a low pass filter.
Band Pass Filter with Offset and Gain Trimming
The following circuit will the use of an RC filter (Potx and
Cx) will filter at the selected frequency. that frequency is
determined by the rheostat value (R
the capacitor value (Cx). each additional stage of the RC
filter is used to enhance the roll-off characteristics for the
filter. The capacitors Cx should be the same, while the
wiper values of the Pots should be similar. The differences
would be to compensate for the slight variations of the R
values of each Pot and the variations of the capacitors.
Programmable Filter
12
V
IN
Digital Potentiometer Solutions
A
B
B
R1
Pot1
R2
W
Digital Potentiometer Design Guide
W
Pot2
A
C2
V
B
R3
IN
W
Pot1
C2
B
A
W
Pot2
BW
C1
) of the Pot and
A
+
-
+
R4
C1
-
V
V
OUT
OUT
AB
The following circuit shows a Wheatstone Bridge with
current limiting. In a Wheatstone Bridge, there are four
resistive elements. In this example, two are fixed value
(R1 and R2), there is a resistive sensor (R
there is the digital potentiometer in rheostat configuration
to calibrate the circuit due to variations of the resistive
sensor. This sensor could be for temperature or weight
measurement.
At a default condition the sensor should be a given
value, but this value will change from device to device.
To compensate for the resistive changes in the R1 plus
R
for the R2 plus Rheo2 leg of the bridge. This would be
done so that the voltages of V
desired levels. Many times this is V
Now as the conditions on the sensor change, the
resistance of the sensor will change, causing the V
voltage to change. The delta voltage between V
V
system (temperature, weight, etc.).
Rheo 1 is used in a rheostat mode to limit the current or
trim the current through the Wheatstone Bridge.
Wheatstone Bridge Trimming
Implementing a More Precise Rheostat
The R
much as ±20%, so a device with a 10 kΩ R
have an R
12 kΩ. In a system, this variation for the rheostat value
may not be desirable. This variation can be calibrated out
to make a precise rheostat, at a cost of the resolution of
the device.
If we design the application circuit where this rheostat
only operates from 0Ω to 8 kΩ, all digital potentiometer
devices (over process) will meet this requirement. Now
with calibration, we will need to ensure that the wiper
value is limited to a value where the rheostat value is the
closest resistance value to the desired rheostat target
value of 8 kΩ. The worst case (lowest) wiper value occurs
when the R
of 171. results in a resistance of 8016Ω. This results in a
resolution of approximately 7.4 bits, or 0.58%.
In potentiometer mode, the process variation of the R
value may not be an application issue since the device is
operating as a voltage divider.
BRG
SENSOR
2
AB
can then be used to determine the state of the
leg of the bridge, the Rheo2 would be modified
value of a typical digital potentiometer can vary as
AB
AB
V
BRG
value as small as 8 kΩ, as large as
value is 12 kΩ. In this case, a wiper value
2
R
SENSOR
R1
A
B
BRG
Rheo1
1
R2
Rheo2
and V
BRG
W
1
= V
BRG
SENSOR
V
AB
BRG
2
BRG
are at their
value could
2
1
BRG
.
) and then
1
BRG
and
AB
2