FW: [sdiy] Powering ICs from a Voltage Divider

[Simon Brouwer]

Jerry Gray-Eskue schreef:
>
>
> -----Original Message-----
> From: Jerry Gray-Eskue [mailto:jerryge at cableone.net]
> Sent: Thursday, October 15, 2009 7:20 AM
> To: Justin Owen
> Subject: RE: [sdiy] Powering ICs from a Voltage Divider
>
>
> Good question,
>
> I am looking at using a similar op amp supply voltage setup. The obvious
> concern is current levels the op amp  can handle gracefully. The second
> not
> so obvious concern is whether you will get any power on/off  transients
> while the circuit stabilizes. A third concern would be the stability of
> the
> voltage under varying load conditions, this would relate to how much
> variation the load will have and slew rate of the voltage follower.
>
> The first item, current level is easy to verify. The second is a trickier
> proposition, to be sure you may have to build it, put a storage scope on
> it
> and power cycle it several times to be sure. A bad transit could be a show
> stopping chip killer. Putting a largish cap 10 - 100 uf on the op amp
> outputs to eat fast transits may be prudent.

An opamp with unity gain feedback and a capacitive load is a recipe for
instability.

-- 
Vriendelijke groet,

Simon Brouwer