Breaking News
Design How-To

Calibrate a power supply with a digital potentiometer

NO RATINGS
More Related Links
View Comments: Oldest First | Newest First | Threaded View
stricula
User Rank
Rookie
re: Calibrate a power supply with a digital potentiometer
stricula   2/16/2012 8:54:31 PM
NO RATINGS
Had a colleague try this in a design. Worked well until ESD testing. Just wanted to present that potential pitfall. Ended up re-purposing that digital pot control output to PWM into an RC filter. The RC filter output was connected to a resistor which went into the feedback node of the regulator. The micro was always reading the voltage out of the regulator. It was an obvious solution once realized that the feedback node is ideally a fixed voltage; lower value than specified = more power commanded out. Makes for an easily configurable and adjustable power supply.

sharps_eng
User Rank
Rookie
re: Calibrate a power supply with a digital potentiometer
sharps_eng   2/17/2012 8:05:21 PM
NO RATINGS
Agreed - replacing a hardware device with a digital pot which contains a bunch of registers, non-volatile or not, increases the state complexity of the system. It may make a better system, but it makes a different system which needs to be tested differently. The ESD /EMI compliance issue is just one manifestation of this. Also: make sure you choose the right version of the pot chip, you don't want your systems to be powered up first time, set at the wrong end of the pot when you want it to be set in the middle.

BicycleBill
User Rank
Rookie
re: Calibrate a power supply with a digital potentiometer
BicycleBill   2/17/2012 9:18:34 PM
NO RATINGS
Certainly, it's not a solution to every design situation, but it gives you new degrees of freedom and flexibility--and along with that, comes responsibility!

Flash Poll
Radio
LATEST ARCHIVED BROADCAST
Join our online Radio Show on Friday 11th July starting at 2:00pm Eastern, when EETimes editor of all things fun and interesting, Max Maxfield, and embedded systems expert, Jack Ganssle, will debate as to just what is, and is not, and embedded system.
Like Us on Facebook

Datasheets.com Parts Search

185 million searchable parts
(please enter a part number or hit search to begin)
EE Times on Twitter
EE Times Twitter Feed
Top Comments of the Week