Digital Potentiometers - Open Circuit?

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deb4523

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Alaska, USA
Does anyone know if there are momentary open circuits while using digital potentiometers or if there is a smooth transition from one setting to another?
 

synchro

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Chicago, IL
Occupation
EE
Does anyone know if there are momentary open circuits while using digital potentiometers or if there is a smooth transition from one setting to another?

Analog switches such as those inside the AD5252 consist of NMOS and PMOS FETs in parallel, and they are turned on and off by internal digital signals. There may be either overlap or non-overlap of the time that two different switches are ON when making a transition between two settings, depending on the internal timing of the control signals that drive the switches. The spec sheet doesn't provide that much detail. The output settling time is specified at 0.2 microseconds typical and therefore the duration of an open circuit condition, if present, would have to be substantially less than that value.
What is the particular concern about having a momentary open circuit? If there is such a concern then some small added capacitance may limit any voltage excursions that may occur.
 

deb4523

Member
Location
Alaska, USA
Analog switches such as those inside the AD5252 consist of NMOS and PMOS FETs in parallel, and they are turned on and off by internal digital signals. There may be either overlap or non-overlap of the time that two different switches are ON when making a transition between two settings, depending on the internal timing of the control signals that drive the switches. The spec sheet doesn't provide that much detail. The output settling time is specified at 0.2 microseconds typical and therefore the duration of an open circuit condition, if present, would have to be substantially less than that value.
What is the particular concern about having a momentary open circuit? If there is such a concern then some small added capacitance may limit any voltage excursions that may occur.

Great idea. Thanks!
 
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