TPS53679: Device not detecting on PMBUS and incorrect VREF

Kunal Chakraborty

Part Number: TPS53679
Other Parts Discussed in Thread: UCD90160, TPS536C7

Hello

We are using TPS53679 power controller device. We applied 3.3V (no 5V and 12V) but TPS53679 device is not detected by TI USB dongle. There are 2 TPS53679 devices, 1 UCD90160 and 1 TPS536C7 device on the same PMBUS. TPS536C7 and UCD90160 devices are detected. But none of the TPS53679 is detected.

Few observations regarding this:

After applying 3.3V, VREF voltage is 1.55V (pin 1)[for both TPS53679]
After that 5V is turned on for power stage. Now VREF = 2.3V (for first device) and 1.85V(for 2^nd device)

Expected VREF as per datasheet is 1.7V. Please let us know possible causes for this issue.

Regards

Kunal

over 2 years ago

0 Travis Williams over 2 years ago

TI__Expert 8960 points

Hi Kunal,

Could the devices be damaged? This is very strange behavior.

Thanks,

Travis

+1 Kunal Chakraborty over 2 years ago in reply to Travis Williams

Prodigy 20 points

Hi Travis

Here is an update on the issue. We connected ASKIP pin to En/FCCM of power stage and also the signal was pulled up to 5V with 0Ohm resistor. Actually either one of R1 and R2 should have been unmounted.

As of now we have removed R1 and the device is detected on PMBUS.

Regards

Kunal

+1 Travis Williams over 2 years ago in reply to Kunal Chakraborty

TI__Expert 8960 points

Hi Kunal,

Looks like the issue is solved, then. I'll close the thread. If you have additional questions, reply to this post to reopen the thread.

Thanks,

Travis

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TPS53679: Device not detecting on PMBUS and incorrect VREF