LM5180EVM-S05: Vout 15V, Change is Transformer

BJ Han

Expert 2035 points

Part Number: LM5180EVM-S05
Other Parts Discussed in Thread: LM5180

Dear TI,

I'm testing the LM5180 EVM board only by changing the transformer.
Please refer to the attached Transformer specifications.
The problem is that the output is changing according to the input.
The output follows the same input. (12V Input -> 15V output / 20V input -> 23V output)
In addition, when the load is input, the output is down.
Is there a problem? Or, is the trans design wrong?
(The primary circuit does not have a fluctuating value. (Existing test board setting value)190213_EFD1515_2 SECTION 사양_10EA.xlsx

over 6 years ago

0 Arief Hernadi over 6 years ago

TI__Mastermind 23845 points

Hi,

You might want to try this EVM instead because this one is designed to have 15V output
www.ti.com/.../lm5180evm-dual

Also for transformer you can compare with this one
www.coilcraft.com/transsel_4-70.cfm

It seems that your transformer leakage inductance is quite big compared to the one on the EVM

Thanks
-Arief

0 Timothy Hegarty over 6 years ago

TI__Guru 74052 points

Hi BJ,

Please send your schematic and a completed LM5180 quickstart calculator file for your design.

Note that Coilcraft has a unity turns ratio transformer, YA9035-AL, that may be suitable for your 15V output design. However, it only provides functional grade isolation. You can contact them directly if you need samples.

Regards,

Tim

0 BJ Han over 6 years ago in reply to Timothy Hegarty

Expert 2035 points

Dear Arief and Tim,

Thanks for the confirmation.

I have not written a schematic yet.

The reason for this is that it is unclear whether the EVM board is used until it is resolved because there is a problem in the EVM Board test with the existing transformer in use. (Transformers reviewed at LT8301)

Do you have any problem with the trance specification I attached?

Or should I change the time constant value on the EVM Board?

Transformer specifications.xlsx

LM5180 PSR Flyback Quickstart Calculator(Single Output development concept).xlsx

0 BJ Han over 6 years ago in reply to BJ Han

Expert 2035 points

Dear Arief and Tim,
I have additional questions.
What does a zener diode do at the output stage?
Does it cause problems when I uninstall it?

0 Arief Hernadi over 6 years ago in reply to BJ Han

TI__Mastermind 23845 points

Hi,

The zener is to maintain the output so that you dont overvoltage your downstream device with higher voltage than that.
So i would recommend to have the zener in there as a protection device.

Thanks
-Arief

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LM5180EVM-S05: Vout 15V, Change is Transformer