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Topic: Need help with LM2575T (Read 248 times) previous topic - next topic

fodelement

Jun 17, 2019, 04:59 am Last Edit: Jun 17, 2019, 05:01 am by fodelement
Hello all,

I am attempting to build the attached circuit found in the datasheet of the LM2575T.

The second attachment is of the PCB I built.

I am using the below items.

LM2575T-5.0/NOPB-ND

ELL-CTV331M

ECA-1HHG331

EEU-FR1C101B


1N5819 Schottky 1A 40V

I am using a 12V PSU.

The issue is on the output of the circuit, where I would expect 5V, I am getting 0.13.


This is the first time I tried anything like this, so I assume I am doing something wrong. Does anyone have any ideas?

Thanks :)








MorganS

OP's images...




D1 appears to be backwards on the PCB.

It also appears that you did not read page 12 of the datasheet "Layout guidelines." The grounds of the LM2575, C1, Cout and D1 must be very close together. You have the feedback wire cutting in between them. That datasheet is also a little sparse on layout guidelines. Sometimes they will show you a suggested PCB layout.

It's not really a chip for beginners. If you can buy it already soldered onto a module then that's always better.
"The problem is in the code you didn't post."

fodelement

#2
Jun 18, 2019, 03:17 pm Last Edit: Jun 18, 2019, 03:17 pm by fodelement
D1 appears to be backwards on the PCB.

Hello MorganS,

Thank you for your suggestion and feedback.

Swapping the polarity of D1 has resolved my issue. :)

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