TSP54332 with certain date markings not working in my circuit

Sandeep Paudel

I have designed and fabricated an application powered by TSP54332.

Conditions are: Ip: 10-20V

Op: 5V

I: 2.5A

After the assembled PCB came back from my Chinese manufacturer, I found that the chip they have assembled did not work in my circuit. When I changed the IC, the circuit worked.

The chip that did not work has following markings on the SMD package:

54332

TI 07H

ZJ02 G4

I've attached my circuit for your reference:

over 11 years ago

0 Sandeep Paudel over 11 years ago

Prodigy 30 points

Can anybody help me in finding out what the problem is?

0 JohnTucker over 11 years ago in reply to Sandeep Paudel

TI__Guru**** 191445 points

You did not state anything about the nature of your problem. How many bad ICs did you test out of how many total systems? What is your distribution channel? Are you sure the ICs came from a legitimate supplier?

0 Sandeep Paudel over 11 years ago in reply to JohnTucker

Prodigy 30 points

Thanks for your prompt response.

The problem with the IC was that the output voltage is 1.7Volts instead of 5V. There was no voltage at the Soft Start pin. I tested a total of 5 such PCBs(samples). Out of 5 , 4 ICs had such markings and those 4 were showing the same problem.

I got that IC through my Chinese supplier. Are you hinting that there can be fake ICs with same part no.s?

0 JohnTucker over 11 years ago in reply to Sandeep Paudel

TI__Guru**** 191445 points

While it is rare, counterfeit ICs are not unheard of, especially if you do not purchase them thru authorized distribution channels. The lower of the SS pin voltage and the internal reference is the input to the internal error amplifier. If the SS voltage is lo, then the output voltage will be low as well. Is the device switching? is there a pulse train on the PH pin?

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TSP54332 with certain date markings not working in my circuit