PTH08T220W: is getting too hot

Hello Stalker,

Thank you for the detailed information on the capacitors. Firs thing that seems concerning is why at no load the device is pulling 500mA. The device should be behaving like that. Can you provide more information on your application?

• What is your input connect to? What is the input source? I don't see on the schematic image you provided.
• Can you provide further info on the output, V_MOTOR?
• Can you provide waveforms showing VIN, VOUT, SW Node?
  • Test #1: Schematic as is. Leave R8 populated.
  • Test #2: Do not populate R8. Leave Pin 11 open.

Thanks,
Alejandro

Hi Alejandro,

Thank you for quick reply.

Input is connected to the bench Power Supply.

V_MOTOR is set to 3V; 

Desire Output Current 5-10A

Please see diagrams bellow

Regards,

Stalker

Input Voltage diagram R8 populated 

VOUT R8 populated

Switch node R8 populated

Input Voltage R8 DNP

output Voltage R8

Switching node

Two immediate notices: Vout is really noisy and SW node is behaving abnormally.

Apologies form my side, I should have been more specific -- could you provide all three signals in one single captured waveform?  I'm trying to see the behavior of the SW node along the output ripple. Also, it's hard to determine what the switching frequency is at (adjust the time-scale).

Could you please elaborate on V_MOTOR? What exactly is on the end application?

Thank you again for providing the specs.

Hi iAejandro,

please see 2 plots bellow, first plot R8 populated , second plot R8 is DNP

V_MOTOR currently is NOT connected to anything, eventually it will drive 10 small motors;

Regards,

Thanks for the waveforms. I'm noticing a lot of strange behavior. The output has about a 500mV ripple pkpk and the switching frequency varies.

Is this happening in multiple Modules? or this one device? Have you tried to isolate the module from rest of system and only monitor the device? If comfortable, please share the PCB layout files to review.

yep, happens on few modules 

I will try to replicate the following circuit on my lab bench and share with you the details. Expect a reply sometime mid next week. We are waiting on some sample material to arrive to place on our test boards. I appreciate your patience. In the meantime, we can review your PCB to double-check.

Hi iAlejandro,

Any updates?

The sample material has been delayed. I will make sure to keep you updated as soon as I received the material. Thank you for your patience!

Hello,

I received some of the material and tested on our bench. I do not get your results on our end.

We populated our test board with the same values you provided and got the following results:

• At no load, input current is at 166mA
• At 3-A, input current is at 910mA. I let the 3-A load running for more than 10min and did not experience any shutdown.

We would advise to double-check your PCB layout. Also, we noticed a high ripple on the output from the waveforms you provided. We would recommend to increase the output capacitance for an improved output ripple.

Regards,
Alejandro

iAlejando,

can you please provide image of your prototype? also do you mind to share scope plots as well, similar to what I posted above?

Thank you