LMR36520:LMR36520

jiri kotal

Part Number: LMR36520

Tool/software:

Hello, I have voltage Uin=42V and Uout=24V. The connection is Rfbt=100k, Rfbb=4.3k, L=47uH, Cout= 4*22uF. When the output is loaded from 250mA to 2A, I have a ripple up to Uout=50mV. If I do not have a loaded output, then I have a ripple of Uout=130mV. Where can the problem be?

2 months ago

0 Rahil Ajani 2 months ago

TI__Expert 6560 points

Hi,

Please provide is with a schematic.

Thanks,

Rahil

0 jiri kotal 2 months ago in reply to Rahil Ajani

Prodigy 20 points

Hi Rahil Ajani,

I am sending the schematic and the PCB board. I also send output Uout=24V and ripple 107mV.

0 Rahil Ajani 2 months ago in reply to jiri kotal

TI__Expert 6560 points

Hi,

An engineer has been assigned to this. Please expect a reply mid-week.

Regards,

Rahil

0 Richard Fu22 2 months ago in reply to jiri kotal

TI__Mastermind 25070 points

Hi Jiri,

If you are using a auto-mode light-load operating mode, the output ripple will be higher due to pulse-mode switching. What is the OPN of the device?

Thanks,

Richard

0 jiri kotal 2 months ago in reply to Richard Fu22

Prodigy 20 points

Hi Richard,

I don't know what OPN means? Can you describe it to me? The DC/DC source powers inductive sensors and LED lights. So the consumption can vary from mA units to 0.5A. That depends on what the user connects to the source.

Thank you

Jiri

0 Richard Fu22 2 months ago in reply to jiri kotal

TI__Mastermind 25070 points

Hi Jiri,

I meant something like this:

If your device is not in FPWM configuration, at light load, you will see larger ripple.

Thanks,

Richard

0 jiri kotal 2 months ago in reply to Richard Fu22

Prodigy 20 points

Hi Richarde,

The LMR38520ADDAR is used in our circuit. Do you think that if we use the LMR38520FADDAR then the output voltage ripple will be the same throughout the load range (current = 0 - 2A)?

Will the output ripple be up to 50mV?

Thank you Jiri

0 Richard Fu22 2 months ago in reply to jiri kotal

TI__Mastermind 25070 points

Hi Jiri,

Yes, if you use LMR38250FADDAR, then the output voltage ripple will be the same since it will allow for the same inductor current ripple that you see at heavy load as light load. You should see the same output ripple at 50mV.

Thanks,

Richard

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LMR36520:LMR36520