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Products => Test Equipment => Topic started by: jimmc on March 14, 2016, 08:07:08 pm

Title: AD584 startup problems
Post by: jimmc on March 14, 2016, 08:07:08 pm
I've been playing with a cheap AD584 module (the one with four double links to set the output) and found an interesting problem.

When first powered up from a bench power supply, the module worked normally (set to 10v), changing to a LM78L15 based supply the output would rise to 2v and then very slowly rise to about 4v when it would jump to 10v.
Subsequent restarts were OK even after several minutes powered down. Discharging all the capacitors on the module caused the problem to reappear.
The problem appeared to be caused by a relatively large capacitor (330nF) fitted between pins 6 & 7. The data sheet suggests 10 to 100nF. I replaced the cap with 22nF which appears to have cured the fault.

Has anyone else seen this behaviour?

Title: Re: AD584 startup problems
Post by: lars on March 14, 2016, 08:14:41 pm
Yes I have two of these and both have the same behaviour. After it has reached 10V I see no problem. The outputs have been within 20ppm from stated value (at specified temperature) the last months (unpowered most of the time).