Regulator Output Noise Voltage Spec

TerryC · 22nd January 2006, 11:50 PM

Can someone tell me why the output noise voltage specification is sometimes given as volts, and other times given as volts/Vout? Specifically I'm refering to the 78XX/79XX family of fixed voltage regulators. One manufacturer will spec it as 90uv, and another manufacturer will spec the regulator as 90uv/Vout. I can't believe that one regulator can be so much better/worse than the other.

Stocker · 23rd January 2006, 03:27 AM

believe it. also, that may be one source that just left off the '/vout' part of the units...

search for (IIRC) "finessing voltage regulator noise" which is a nifty paper from Wenzel Assoc., who know about low noise stuff. Also search the forums here as this sort of topic has been discussed before.

davidsrsb · 23rd January 2006, 04:46 AM

Variable regulators noise level increases as the voltage is increased, so the V/V spec makes sense, just multiply the output voltage by this figure.

Fixed regulators like a 7805 can just give a level in Volts.

Of course the V/V figure looks better at a glance

22nd January 2006, 11:50 PM	#1
TerryC diyAudio Member Join Date: Jun 2005 Location: WA-USA	Regulator Output Noise Voltage Spec Can someone tell me why the output noise voltage specification is sometimes given as volts, and other times given as volts/Vout? Specifically I'm refering to the 78XX/79XX family of fixed voltage regulators. One manufacturer will spec it as 90uv, and another manufacturer will spec the regulator as 90uv/Vout. I can't believe that one regulator can be so much better/worse than the other.

23rd January 2006, 03:27 AM	#2
Stocker diyAudio Member Join Date: Dec 2003 Location: Austin	believe it. also, that may be one source that just left off the '/vout' part of the units... search for (IIRC) "finessing voltage regulator noise" which is a nifty paper from Wenzel Assoc., who know about low noise stuff. Also search the forums here as this sort of topic has been discussed before. __________________ Jesus loves you.

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23rd January 2006, 04:46 AM	#3
davidsrsb diyAudio Member Join Date: Dec 2005 Location: Kuala Lumpur	Variable regulators noise level increases as the voltage is increased, so the V/V spec makes sense, just multiply the output voltage by this figure. Fixed regulators like a 7805 can just give a level in Volts. Of course the V/V figure looks better at a glance