Encoders vs. Potentiometers: Which one is best for programmable power supplies?

Posted on

Just lately I requested the product supervisor of TDK-Lambda’s new Z+ Collection of programmable power provides a query, “Why use rotary encoders to regulate the output voltage and present restrict instead of potentiometers?”

“The reply is comparatively easy,” he mentioned; it’s all about digital circuitry compatibility and determination”. The important thing benefit to utilizing a rotary encoder over a potentiometer is that that the digital sign produced by the encoder eliminates the necessity for the analog to digital (A/D) conversion that is required when potentiometers are used. As well as, multi-turn encoders can present extra correct and better decision set-points than potentiometers.

Let’s put this into context: if a single flip potentiometer had been for use to regulate the output voltage on a 20V rated mannequin, one full flip would usually signify 20V; this decision is comparatively low and subsequently not exact sufficient for a programmable power provide. After all, multi-turn potentiometers might be employed however these are bulkier than and never as dependable as encoders are.

Digital rotary encoders can be found with very high resolutions and might function in dual modes, together with a rough and positive mode. Within the coarse mode, the encoder operates with a decrease decision; for instance, a 20V rated mannequin would require about six turns of the encoder knob to regulate the output from zero to 20 volts. Within the positive mode, one flip equates to an roughly 40 millivolts, thereby offering a a lot greater decision and extra exact set-point.

To keep away from an inadvertent change to the voltage setting throughout use, a front panel locking feature is wanted. With an encoder, this locking operate is carried out through software and internal memory, whereas a potentiometer requires a much less dependable mechanical locking mechanism.

The Z+ programmable power provide employs two encoders as set-point controls for the output voltage and present. The encoder’s digital output feeds the unit’s memory, which retains the final set-points previous to the AC power being turned off and on, both deliberately or attributable to an unplanned power outage, and retains the output disabled till the person allows it (aka “safe-start” mode). Within the “auto-restart” mode, the Z+ power provide remembers its final output set-points and when the power is turned again on, it resumes its regular operation, which is helpful for unattended functions.

To see extra particulars together with movies in regards to the encoder pushed Z+ programmable power provides, please use this hyperlink: http://www.us.tdk-lambda.com/lp/merchandise/zplus-series.htm