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Need cheap 40V supply OpAmp with >500mA peak output

Hi folks,

for a low-noise floating +/- 15V-supply running off +/- 18V I'm looking for a simple integrated power amplifier that can deliver about 1.5W rms power into the transformer (~15kHz sine). Interestingly there seems to be a "gap" in available amps: There are plenty of cheap 1-2W audio amps running off 5V, and then there are the big 3A L165 and friends (which, at 36V total supply, burns more than 2W quiescent power).

Of course I can go discrete; I'm just asking if I'm missing the obvious candidate.

Thanks, robert

Reply to
Robert Latest
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It's the cheap part that'll get you into trouble. For example, consider the buf634 at $4.12 qty 100 in the miniDIP package, with a low-noise opamp of your choice. Just how cheap do you want it to be?

--
 Thanks,
    - Win
Reply to
Winfield Hill

Well, ON Semi's TCA0372 fits the bill nicely for .95 at DigiKey. Except that DK is a bit difficult to order from if you're in Europe and you're ordering for a government agency (lots of red tape and steep shipping fee because of overseas order). I've added the chip to my continuously growing "DigiKey-Only" list which hasn't yet reached the threshold at which I think placing an order is justified.

robert

Reply to
Robert Latest

Farnell doesn't have it?

--
 Thanks,
    - Win
Reply to
Winfield Hill

They say they do but at their US sister company Newark, so it is either

pay ~35$ to get it in 3 days or 10$ to get it in 14 days

-Lasse

Reply to
langwadt

"Robert Latest" schrieb im Newsbeitrag news: snipped-for-privacy@mid.individual.net...

Hello Robert,

The LM675 from National or the OPA544 from TI will be your best choice. As far as I remember, the OPA544 is easier to tame.

Best regards, Helmut

Reply to
Helmut Sennewald

I remember reading a US DoD note on the requirements of AC power amplifiers feeding rectifier loads. They recommended a peak current capability equivalent to 4x to 6x the apparent VA requirement.

It might be useful to LTspice the transformer and rectifying load first, in order to see the demands placed on the driving amplifier.

--
Tony Williams.
Reply to
Tony Williams

On Wed, 13 Dec 2006 09:13:11 +0000 (GMT), Tony Williams wrote in Msg.

Good tip. Done it and it came out pretty much like I had figured with pencil and paper as I haven't really made friends with simulators yet. But it's great to be able to see the startup process!

robert

Reply to
Robert Latest

What was your rectifier/smoothing/load, and what sort of current waveshape did it draw into the primary of the transformer?

--
Tony Williams.
Reply to
Tony Williams

I would have recommended the very cheap TDA2030A (although it might have more quiescent current than you want), but here in the UK Farnell reckons that ST have stopped making it, even though the ST website says it is still "active" and available. The TDA2040 has less supply voltage rating and draws more current and costs more but Farnell do admit to having some.

Chris

Reply to
Chris Jones

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