LM5576 EVM, 75V, 3A Step-Down Switching Regulator Evaluation Module

Hong Tay

Other Parts Discussed in Thread: LM5576

Hi Sir/Madam,

The evaluation board provides a 5V output with a 3A current capability. Is it possible to customize the EVM to provide 5V output with 3A?

Thanks.

over 9 years ago

0 Marc Davis-Marsh over 9 years ago

TI__Genius 10115 points

Yes it is possible to customize the EVM the output voltage. I am confused by the question because the EVM has 5Vout. Although not optimized, Changing the bottom resistor R6 from 1.65k to 3.01k will quickly adjust the output voltage to 3.3V. Follow recommendations in the datasheet to adjust other components.
www.ti.com/.../getliterature.tsp

Regards,
Marc

0 Hong Tay over 9 years ago in reply to Marc Davis-Marsh

Expert 2465 points

Hi Marc,

Thanks for the reply. Sorry for the typo error. Actually I am asking for 15Vout and 3A. If to do so, can I just changed the below resistor, R6 to 0.5k ohm to get 15Vout and 3A?

Thanks.

0 Marc Davis-Marsh over 9 years ago in reply to Hong Tay

TI__Genius 10115 points

You could just adjust the resistor but the part would have very high ripple current with the inductor on the board. If you go to the 5576 product folder on ti.com. On the right you will see a webench entry. Type in your paramters and you will receive an entire recommended bom and schematic. It will look something like this.

0 Hong Tay over 9 years ago in reply to Marc Davis-Marsh

Expert 2465 points

LM5576 EVM Test Result 1.pptx

0 Hong Tay over 9 years ago in reply to Marc Davis-Marsh

Expert 2465 points

Hi Marc,

Please help to take a look on LM5576 EVM evaluation result from my end. Please refer to the power point slide attached.

Do you have any idea that why the result is different if changing the design as below?
1) inductor current with and without R7 and C11
2) diode current with and without R7 and C11
3) Vout with and without C10 - C10 is for output filtering right? Why it would affect the output voltage?

Thanks.

0 Marc Davis-Marsh over 9 years ago in reply to Hong Tay

TI__Genius 10115 points

When I recalculated on webench, it recommended a larger inductance value. Some of the issues you are seeing might be because of instability.

Try at least a 47uH inductor.

Regards,

Marc

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LM5576 EVM, 75V, 3A Step-Down Switching Regulator Evaluation Module