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Original question:

TPS552882: TPS552882 failing with shorted VOUT

TPS552882-Q1: TPS552882-Q1 : random VOUT failure observed

Vasantha Priya S
Prodigy 40 points

Part Number: TPS552882-Q1
Other Parts Discussed in Thread: TPS552892-Q1

We are using TPS552882-Q1 as a buck-boost regulator to generate 13.6V with 3A load current.

During testing, we are observing a random VOUT (VCC_PAVDD) failure. In the failed condition:

  • VOUT collapses to 0 V

  • On probing the device, the internal MOSFET appears to be shorted (VOUT, SW2 pins are shorted)

  • No external components (inductor, capacitors, resistors, MOSFETs) are found damaged or shorted.

  • Failure is intermittent and does not occur consistently.

We have tested the design with:

  • Continuous 3 A load current

  • Repetitive load change from 1 A to 3 A every 100 ms

During these tests, no abnormal behavior was observed.

We have attached the schematic and layout images. Kindly let us know if there are any concerns in the design that could cause and  provide feedbacks to avoid this failure. 

image.png

image.png

  • 0
    TI__Mastermind 18730 points

    Hi Vasantha,

    Thank you for reaching out. Can you help check below question:

    1. What is the failure rate?

    2.What is input voltage?

    3.

    Vasantha Priya S said:
    Failure is intermittent and does not occur consistently.

    Do you mean the failure will recover?

    4.Use a multimeter to test the ESD diode for each pin. Set the multimeter to the diode mode, connect the positive probe to GND and the negative probe to each pin, and check if any pin is in an open-circuit state.

    5.Can you provide the waveforms of damage moment including SW1, SW2, Vout and inductor current?

    Regards

    Mulin

  • 0 in reply to Mulin Yuan
    Prodigy 40 points

    Hi Mulin,

    Thanks for your quick feedback. Please find the responses below.

    1.It is not failing on every unit or every test cycle. The failure is random.

    2. Our requirement is 10 V to 30 V input. Currently testing at 24 V.

    3. No. Once damaged, the IC needs to be replaced.

    4. Tested and attached the results

    IC PIN Diode Value (V)
    U13_1 0.589
    U13_2 0.756
    U13_3 0.541
    U13_4 0.646
    U13_5 0.548
    U13_6 0.548
    U13_7 0
    U13_8 0.552
    U13_9
    U13_10 0.76
    U13_11 0
    U13_12 0.651
    U13_13 0.664
    U13_14 0.628
    U13_15 1.128
    U13_16 0.553
    U13_17 0.552
    U13_18 0.552
    U13_19 0.405
    U13_20 0.553
    U13_21 0
    U13_22 0.615
    U13_23 0.477
    U13_24
    U13_25 0
    U13_26 0

    5. We are randomly facing the issue in closed mechanical, At the time of damage moment , we can't able to get the waveforms.

  • 0 in reply to Vasantha Priya S
    TI__Mastermind 18730 points

    Hi Vansatha,

    Below is my feedback:

    1.How many boards have you test in total, and how many failure happens?

    2.What is the working state of IC when failure happens? For example, during start-up, shut-down, load transient or during steady state?

    3.Pin 10 is AGND, the diode volage shouldn't be 0.76V. Can you check it is test issue or design issue?

    4.Fot the 13.6V/3A application, TPS552892-Q1 can support. Do you consider to change to TPS552892-Q1 for lower BOM cost and easy-to-design circuit?

    5.Can you describe the test cycle? What is the power sequence of the test cycle?

    6.For design check, can you provide part number of the inductor and output caps?

    Regards,

    Mulin

  • 0 in reply to Mulin Yuan
    Prodigy 40 points

    Hi Mulin,

    Please find the response

    1. We have tested 10 boards. Out of that 4 boards have failed

    2.During start up

    3.It is a test issue. It is 0V only

    4.No. We done the proto with this TPS552882-Q1, Now we are going to do mass production. Again changing to different part number in this phase means we have to test it again.

    5. First we turn on the 24V after that we will enable the 13.6V Once controller gets powered ON.
    6. Part Numbers:

    8.2uH - 7443330820 - Wurth Electronik

    56uF - RSS1E560MCN1GS - NICHICON

    47uF - CGA9N1X7R1V476M230KC - TDK Corporation

    10uF - GRM32EC72A106KE05L - MURATA

    0.1uF - CC0603KRX7R0BB104 - YAGEO

    We have attached the waveforms during startup below

    TPS552882-Q1 Waveforms (1).pdf

  • 0 in reply to Vasantha Priya S
    TI__Mastermind 18730 points

    Hi Vasantha,

    1. Do you have a chance to modify layout? The main issue is that there is no ceramic capacitors near Vout loop, so the parasitic parameters are huge and will cause large voltage spike. Recommend to put at least two ceramic capacitors near IC Vout pin. Also, there is some other issue like Vin loop, AGND-PGND connection, current sense and drive circuit. Please refer to attached file.

    5850.TPS55288 Layout Guideline.pptx

    2. About the waveforms, there is also some issues:

    EN noise: there is much EN noise in EN pin. Why EN is pulled down here? Recommend to add a 0.1uF/1uF MLCC in EN pin to filter noise. 

    From SW1 waveforms, Vin is ramping slowly and Vout is already stable during start-up. Is this the real working condition?

    Regards,

    Mulin