Bad Voltage Regulator??

Development Boards Arduino
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Hi, I’ve got an arduino product that I’m moving to protoboard, I have a few LM2409 5v regulators and after frying a couple of Atmega chips I looked at the output voltage and it isn’t reducing it at all, so I’ve given 3 chips around 18v (assume they will be dead I cannot burn the bootloader to them, invalid signature, I managed on the other 2 chips that I didn’t connect to this circuit) I’ve also tried a 9v supply and the output from the regulator was 9v too.

I have 3 of the regulators and they all behave the same, are they duff?

Thanks, I’m a relative beginner

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LM2409 ??

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There is an LM240 adjustable regulator, but LM2409 doesn’t fit. The 5V version would be LM240-05 or LM240-5.

Three terminal regulators are pretty straightforward. Verify your pinout.

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LM2409 isn’t a regulator: http://www.ti.com/lit/ds/symlink/lm2409.pdf

5

Sorry for the confusion, LM2940

http://www.maplin.co.uk/p/lm2940ct-50-n … ator-av22y

Got some more and they seems to work.

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Backwards…

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Or missing ground connection …

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Wasn’t backwards, checked and double checked. Ground should have been ok too.

The Atmega chips that was supplied 12v are they dead or is there a way to bring them back? I’m getting avrdude: Device signature = 0x000000. Thanks

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Your definition of backwards and the manufacturers definition of backwards might be two different things. How about you tell us YOUR definition of backwards.

And “ground SHOULD HAVE BEEN ok too” doesn’t mean much either if you’ve got Vout = Vin.

12v on a 5v chip? If that chip had a good ground somewhere, anywhere, then ya, it’s most likely smoked.

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I looked at the specs with the tab at the back Vin was left, ground centre and Vout right. Ground was connected to the - on my 12v supply and I was reading 12v across the Vout and ground pins. Sticking one from the new batch in the same orientation and I get just under 5v and with a new atmega chip all is well now.

11

meh…alrighty then.

Any chance you could’ve static zapped the first couple of 2940’s?

Put a meter across Vin and Vout on the original 2940’s. Should get practically open one way, and about a diode drop the other way.

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No path either way on Vin - Vout. Got the first batch from China via an eBay seller, second batch from a UK supplier.

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So one was faulty and the other two circuits had shorts to earth.

Thanks for the replies

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Lm7805 would be a +5v regulator… 7809 would be a +9v reg… that’s how it got fried…