Hi

Could you please let us know, if the chip can work normal, V5 ok? Vout OK?, and also you can double check on different boards.
If all are OK, would you please upload your schematic for review? thanks.

Frank

Hi Yuchang, I'm attaching my schematic and some scope traces.

C1 = V5, C2 = Vref, 3 = Vout Note that it is measuring on a slow 2s/div range.

You can see the trace starts with no load and changes in the middle when we add a roughly 6A load and back again to no load.

The output voltage is 1.1V but should be 0.85V, this is the same ratio as the actual Vref to the expected 2.0V Vref.

We only have one PCB to test but have change the chip a couple of times and get the same answer.

Ian.

You will see that the Vref voltage is 2.62V with no load and 2.58V with the load applied.

Hello

Circuit looks OK, it is weird, Just give some suggestion for your reference.

1, Please check layout, special 51363 package footprint, make sure the thermal pad ground, has enough via connect to system ground. I suspect if there is a offset at chip ground.

2, I checked 1pcs 51367 EVM vref which is almost same with 51363, looks vref is closet to 2V,  If you have 51363/362/367 EVM, please check the issue chip on EVM.

3, Floating Vref, check the voltage

4, change C18 to 0.22uf and check the voltage.

Yuchang

Hi Yuchang,

We're doing some checking but can't see anything wrong yet.

You mentioned a 51367 EVM PCB - I can't find this on the TI website, please can you give me more details - where can I get one please ?

Thanks,

Ian.

Hi Lan,

I am also confused now, Could you please tell me where you get the chips? TI official or from..? and which version it is?

About EVM, maybe you can ask local FAE for help first.

Yuchang

Hi Yuchang,

we got the 51363 chips as samples from the TI website so they should be ok.

As for the EVM I would happily order one if I knew what to order. There is nothing visible on the TI website for an EVM for any of the family of ICs 51362, 51363 or 51367 so I would not know what to ask a local FAE for even if I knew who to ask!

I can't continue to use this chip in my design unless I get this sorted so I'm thinking of trying a different part - I need 2 PSUs: 0.85V and 1.0V both at 10A and with remote voltage sensing and powered from 6 to 17V, could you please suggest any other parts ?

Thanks,

Ian.

Hi Yuchang,

oops, how embarrassing, I went through the board again and finally found that the GSNS pin was at 0.6V because the zero ohm resistor that should connect it to ground at the load point was for some reason open circuit. Now it's soldered across and Vref is 2.0V and the output is 0.85V as intended. Thanks for your help in looking at the circuit, it just wasn't obvious what was happening. We can continue with our design now!

Best wishes,
Ian.

Hi Lan,

Good news ~~~~
I just suspected GND offset, but havent thought GSNS circuit open accident.
and remind that take care the Vsns and GSNS routing, avoid switching noise coupling..and you can follow the layout remmendation in Datasheet.

yuchang