TPS82084: TPS82084SILT no output

Pavithra M

Intellectual 500 points

Part Number: TPS82084

Hi,

I have used the TPS82084SILT for 5V to 3.3V conversion with 499k as PG pull-up, R2=150k,R1=465K.

Input voltages measured are: EN,VIN are 5V

But output is zero.

The inductor above the IC is measuring 4.35V on one side(near to pin 8) and 4.27 on opposite side.

So is the IC generating output??

Output voltage is always zero even when I kept PG pin as floating

VFB is also zero.

What can be the issue?

How can I troubleshoot?

Regards,

Pavithra.

over 5 years ago

0 Chris Glaser over 5 years ago

TI__Guru**** 150650 points

Hi Pavithra,

Somehow you made 2 posts about this issue, so I deleted the other duplicate one.

Do all boards show this same issue? How many have you tested?

Can you share your schematic and PCB layout?

Can you send a waveform (from an oscilloscope) of Vin, EN, and both sides of the inductor?

0 Pavithra M over 5 years ago in reply to Chris Glaser

Intellectual 500 points

The SD is attached.

Will share the waveforms soon.

TPS82084.docx

0 Chris Glaser over 5 years ago in reply to Pavithra M

TI__Guru**** 150650 points

Thank you for the files. The schematic looks ok.

Can you just send a print screen of the PCB layout? Gerbers are difficult to view.

As well, can you measure waveforms of Vin, Vout, and both ends of the inductor?

Do all PCBs show this same issue?

0 Pavithra M over 5 years ago in reply to Chris Glaser

Intellectual 500 points

I have made only 2 PCBs of which one only I have assembled and was testing section by section.

I will receive the next board assembled in 2 days time. I will check in that new PCB also once and revert back.

0 Chris Glaser over 5 years ago in reply to Pavithra M

TI__Guru**** 150650 points

Yes, let's see if other boards show the same issue.

On the layout view, can you zoom out to see the entire input and output caps? They look rather far away from the IC and not routed directly to the pins. You can see figure 30 in the D/S for an example of where those caps need to be--closest to the device.

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TPS82084: TPS82084SILT no output