TPS62480EVM-671: Output current is not Exceeding 3.74A at 3.3V Output

Samson P1

Part Number: TPS62480EVM-671

We are working on TPS62480EVM-671 module. We changed the FB resistors to 540K & 120K for VOUT=3.3V and VIN is 5V. We set the VSEL=LOW, MODE=LOW and RS pin Shorted to ground. We have connected 0.6A load resistor to check the Iout=5.5A. But the Output current is never changing beyond 3.7A.

Please let us know your thoughts on this.

over 3 years ago

0 Davor Pavlovski over 3 years ago

TI__Expert 3611 points

Hi Samson,

Could you check that the power supply you are using is not current limited at 3.7A? Does the EVM work as it should for lower current loads?

If that is not the issue, could you send the input and output voltage waveforms while you have the 0.6ohm resistor connected as a load.

Regards,
Davor

0 Samson P1 over 3 years ago in reply to Davor Pavlovski

Prodigy 100 points

Hi Davor,

Thanks for the Reply.

The input power supply is rated for 7A.

Our requirement is Vout=3.3V and Iout=6A.

Please confirm the Configuration details for 3.3V Output voltage & 6A output Current.

We connected as per the Webdesign SCH.

VSEL=Low

MODE = Low(PSM)

RS= Connected to Ground.

FB resistors: R1=540K & R2=120K

Do we require any changes for the configuration?

Regards,

Samson

0 Davor Pavlovski over 3 years ago in reply to Samson P1

TI__Expert 3611 points

Hi Samson,

For further analysis, can you please provide the waveforms of Vin, Vout and Iout during start up.

Regards,

Davor

0 Samson P1 over 3 years ago in reply to Davor Pavlovski

Prodigy 100 points

Hi Devor, Please find the snapshots.

Regards,

Samson

0 Dorian Brillet de Cande over 3 years ago in reply to Samson P1

TI__Genius 14856 points

Hello Samson,

EVM should work fine with the configuration you have.

I want to verify with you your lab setup. Could you double check your load when you do the startup?

My assumption is that directly at startup you hit the current limit and that is why you see this limitation.

What happens if you connect your load after startup?

Let me know!

Regards,
Dorian

0 Samson P1 over 3 years ago in reply to Dorian Brillet de Cande

Prodigy 100 points

Hi Dorian,

As you can see in the waveform, at start up there is no spike/transient at IOUT signal.

What is the Current limit for this IC?

Regards,

Samson

0 Dorian Brillet de Cande over 3 years ago in reply to Samson P1

TI__Genius 14856 points

Hello Samson,

Current limit for this device is 5.0A typical per phase which should be 10A output current in average.

I was suggesting this because it is specified in the datasheet the following: "if the current limit situation remains for 512 consecutive switching cycles, the peak current folds back to about 1/3 of the regular limit". Which could relate to what you see here with 3.7A.

Have you tried different load conditions at startup or after startup to see if you still see this issue coming up?

Let me know!

Thanks a lot!

Regards,
Dorian

0 Dorian Brillet de Cande over 3 years ago in reply to Dorian Brillet de Cande

TI__Genius 14856 points

Hello Samson,

Can you also capture the SW node waveform at startup and steady state?
Thanks a lot!

Regards,
Dorian

0 Dorian Brillet de Cande over 3 years ago in reply to Dorian Brillet de Cande

TI__Genius 14856 points

Hello Samson,

I haven't heard back from you!

Were you able to do the capture of the waveforms ?

Let me know!

Thanks a lot!

Regards,
Dorian

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TPS62480EVM-671: Output current is not Exceeding 3.74A at 3.3V Output