AD5280BRU200 查看數據表（PDF） - Analog Devices

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AD5280BRU200

15 V, I2C Compatible 256-Position Digital Potentiometers

Analog Devices 

AD5280/AD5282

Resistance Tolerance, Drift, and Temperature Coefficient

Mismatch Considerations

In a Rheostat Mode operation such as gain control, Figure 27,

the tolerance mismatch between the digital potentiometer and

the discrete resistor can cause repeatability issues among various

systems. Because of the inherent matching of the silicon pro-

cess, it is practical to apply the dual-channel device in this type

of application. As such, R1 should be replaced by one of the

channels of the digital potentiometer. R1 should be programmed

to a specific value while R2 can be used for the adjustable gain.

Although it adds cost, this approach minimizes the tolerance

and temperature coefficient mismatch between R1 and R2. In

addition, this approach also tracks the resistance drift over time.

As a result, these nonideal parameters become less sensitive to

the system variations.

B R2 A

W

Notice the circuit in Figure 28 can also be used to track the

tolerance, temperature coefficient, and drift in this particular

application. However, the characteristics of the transfer function

change from a linear to pseudo-logarithmic gain function.

R

AB

W

C1

AD8601

VO

Vi

U1

Figure 28. Nonlinear Gain Control with Tracking

Resistance Tolerance and Drift

R1*

C1

AD8601

VO

Vi

U1

*REPLACED WITH ANOTHER CHANNEL OF RDAC

Figure 27. Linear Gain Control with Tracking

Resistance Tolerance and Drift

REV. 0

–19–

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