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 fmak 26th January 2006 03:10 PM

ALW Regulator Current Limit?

I have just tried a fully tested 12V unit to power a dac with a current requirement of 670mA but the unit just shuts down. I can find nonreference in the literature on current limit.

Am I overdrawing current?:confused:

 Whit 26th January 2006 04:45 PM

Andrew told me a few weeks ago that the current is limited by the preregulator.

 Darry 26th January 2006 05:08 PM

Between 200 and 500mA
To see : Alwsr rev2.9rev0051.pdf
just above figure 2 ( page10 )

Darry

 Whit 26th January 2006 08:06 PM

Look here at post #206.

 peranders 26th January 2006 08:42 PM

Re: ALW Regulator Current Limit?

Quote:
 Originally posted by fmak I have just tried a fully tested 12V unit to power a dac with a current requirement of 670mA but the unit just shuts down. I can find nonreference in the literature on current limit. Am I overdrawing current?:confused:

Do you have cooling, not :hot: LM317 or D44H11?

Max current can be calculated backwards.

Hfe 25 min, typ 100 of the D44H11

Current through driver 1V/R1 => 10 mA

That gives max current somewhere between 250-1000 mA but more like the higher value.

The very current limit is set by the LM317, check datasheet for this (1-1.5 A)

 fmak 27th January 2006 04:57 AM

Re: Re: ALW Regulator Current Limit?

------------------------------------------------------------------------------------15-17V
------------------------------------------------------------------------------------

Do you have cooling, not :hot: LM317 or D44H11? -YES
------------------------------------------------------------------------------------

Max current can be calculated backwards.

Hfe 25 min, typ 100 of the D44H11

Current through driver 1V/R1 => 10 mA

That gives max current somewhere between 250-1000 mA but more like the higher value.
------------------------------------------------------------------------------------

These values are about right; so why does my regulator shut down at 600mA?

:confused: :confused:

 peranders 27th January 2006 06:09 AM

Notice at least 250 mA but how much load can it take then?

What does "shut down" mean? A bit voltage drop or what?

Your input voltage with ripple taken into account, min voltage? It must be 15-16 V at least plus ripple.

 fmak 27th January 2006 08:38 AM

Quote:
 Originally posted by peranders Notice at least 250 mA but how much load can it take then? What does "shut down" mean? A bit voltage drop or what? Your input voltage with ripple taken into account, min voltage? It must be 15-16 V at least plus ripple.
------------------------------------------------------------------------------------
My apology; I treated a 15V regulator as though it was 12V; the thing never started even though the LED was on.

Happilly now getting 650 mA on 12 V with 18V input. Now testing geat sink temperature.

My rme dac sounds much better on ALW than LT1085 variable or manufacturer's 'good' switching supply. No hf fixx and more open!.

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