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TPS53355: PGOOD failing below 10Deg C

Ansuman Dutta
Prodigy 10 points
Part Number: TPS53355

Tool/software:

Hi TI Team,

We are facing issue with some boards where PGOOD is failing below 10Deg °C but are stable at 25Deg °C. Please find below observations and Circuit diagram and help in reviewing the design and suggest possible cause for this fault.

Design info:

Parameters: Vin: 12VDC, Vout: 3.3VDC, Iout(typ): ~1Amp, FSW: 650KHz, CCM.

Where used: To power rails of Intel XEON_D1527 (VCCSUS3_3, VCCCLK3_3, VCC3_3).

Observation:

1. VR_P3V3_CPLD_EN(Enable) is stable in both case 25Deg °C and 6Deg °C, i.e ~3.28VDC

2. Vout observed at C7M1 is 3.342V@ 25Deg °C and 3.280V@ 6Deg °C

3. PGOOD is observed ~3.26V@ 25Deg °C but fails ~0V@6Deg°C.

Schematic:

  • 0
    TI__Mastermind 32360 points

    Hello Ansuman, 

    Can you please provide a plot on what happen on the above conditions? i need see the PG falling by 10C. is 10C a temperature (PGOOD is failing below 10Deg °C)?

    do you VOUT, PG, IOUT(Load) and IIN when the issue happens? 

    is this board related or IC related? you can check this by doing ABA test by changing a pad unit with a known good know unit on the board that shows issues and verse versa. 

    Thanks 

    Tahar