TPS63070: TPs63070 wrong output voltage

To add PG is low so something is wrong

Hello Amir,

If the feedback voltage is 1.9V, something is totally wrong. Please re-post the schematic as it is not easy to read. In addition, please check your GND connections in detail, especially the GND pin of the feedback resistor divider.

Best regards,
Brigitte

Hi,

I have attached the schematic and PCB  in pdf. I also I double check all the ground and it fine.

even the voltage divider is working since 11.5*34k/(34k+165k) = 1.965.

As I mentioned before PG (power good ) is low.

Thank you

6505.schematic.pdf

2133.pcb.pdf

Hello Amir,

Thank you very much for the schematic and layout.

In the schematic you show a 330nH inductor. It is recommended to use at least a 1uH inductor for this design.
Please check what is happening if you exchange the inductor with a 1uH or 1.5uH inductor. It is possible that the converter is instable with such a small inductor value.

If possible, please measure the switch nodes and the output voltage with an oscilloscope.

In the attached layout, the planes are not flooded, correct? You are using extremely thin thermals for the planes, if possible please increase the width of the thermals for a better layout best would be to not use thermals at all, but flood directly. Thermals are normally not needed anymore because the soldering is almost always happening in a reflow oven where the whole board is heated.

Best regards,
Brigitte

Hi Brigitte,

The plane is flooded as the datasheet mentioned and in my next batch, I will remove the thermals and flood all the way. I even change the inductor to recommended device but I am still getting 11.5V as output and 1.9 for FB.

After hours of troubleshooting, I connect 10k ohm load to the regulator which decrease the output voltage to 5.15v and FB to 0.6. The regulator is only stepping up the voltage and not down. Below is scope from the inductor Lout when input is 4.7v output voltage is 5.28V =>FB 582mV => PG = LOW

VIN

Vout

What could cause this issue? is the schematic and footprint correct.? Does the 10uF capacitor could do this.

Thank you 

Hello Amir,

Which 10uF cap are you referring to? I do not have an explanation for this behavior. Is it possible that the IC is damaged? What happens if you exchange the IC?

I do not understand the following sentence:
After hours of troubleshooting, I connect 10k ohm load to the regulator which decrease the output voltage to 5.15v and FB to 0.6.

If you want to have 4.7V on the output as you mention in your first mail and your resistor divider is working properly, at an output voltage of 5.15V you should get a FB voltage of 880mV and not 600mV. So there is something strange going on.

Please check with a different IC!

Best regards,
Brigitte

Hello Brigitte,

I change the IC but still, I am getting 11.5V output voltage when Vin is only 5V and FB is 1.9. 

I am out of idea what could be the problem. I think I found the problem I am using  TPS630701 instead of TPS63070

I order the correct one I will update you as soon I receive the correct part.

Thank you