TPS53353 breakdown

Lasse Dahl

Other Parts Discussed in Thread: TPS53353

We have just entered mass production of a projector where the TPS53353DQP is used as a converter for FPGA core voltage. We have already manufactured approx.100pcs without problems but now we have 3 boards of 15 where the TPS53353DQP is damaged. For the moment we have full attention on the manufacturing process but we also need to understand critical mechanisms that could cause TPS53353DQP damage. The nature of the IC damage is short circuit between Vin, LL and GND which seam to be a breakdown of both MOSFET's in the output stage.

We have measured Vin on the board during relevant processes during manufacturing but can not see any transient voltages above 15V. Max temperature of the TPS53353DQP during the manufacturing process(after soldering) is 65C

Is there any other critical conditions or settings of the TPS53353DQP that could cause breakdown of the internal output MOSFETS (e.g. cross conduction).?

over 9 years ago

0 JohnTucker over 9 years ago

TI__Guru**** 191445 points

Usually that type of failure occurs from electrical overstress such as over voltage above the abs max rating. Searching for failure information, only one case is recorded. The device was damaged such that no further analysis was completed. I suggest you submit a failing device for FA.

0 Lasse Dahl over 9 years ago in reply to JohnTucker

Prodigy 100 points

Thanks John, I will see if we have failing devices for FA. I just had a look at the LL output and the frequency changes between 490 and 520KHz. I would expect more stable fixed 500KHz pulses. When I increased load with 10A for a moment i still had the same frequency "jittering" so this seems to be load independent. I know some controllers do frequency jittering to reduce EMI but i can not see anything like that in the datasheet of this controller. Please comment

0 JohnTucker over 9 years ago in reply to Lasse Dahl

TI__Guru**** 191445 points

TPS53353 uses DCAP control. There is no internal oscillator to set the frequency. It is adaptive on time / hysteretic off time control, so the frequency and duty cycle may vary from pulse to pulse. I doubt that has any correlation to your failures.

0 Lasse Dahl over 9 years ago in reply to JohnTucker

Prodigy 100 points

Hi John,

We have some damaged devices that is relevant for failure analysis(FA). Can you please put me in contact with the right people to do FA?

Lasse

0 JohnTucker over 9 years ago in reply to Lasse Dahl

TI__Guru**** 191445 points

Who is your local FAE?

0 Lasse Dahl over 9 years ago in reply to JohnTucker

Prodigy 100 points

I do not have a direct TI FAE contact but I have now contacted our Silica FAE Håkon Helsing and he has further contacted TI and requested a failure analysis of the IC.

I have also had a closer look at the Vdd connection and probably found an unwanted connection between Vdd and Vin. The intention of routing +12V to Vdd(pin19) is to do that via a capacitor on bottom(blue) layer. The 12V plane(cyan) will short circuit Vdd almost directly to Vin(pin12-17) and probably introduce more switching noise. I have been told by FAE Jan Volkering (TI Holland) that Vdd routing is critical. Could this be the reason why the circuit break down?