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TPS1689EVM: Not starting up if there is load

Kei Kuwahara
Expert 8150 points
Part Number: TPS1689EVM
Other Parts Discussed in Thread: TPS1689

Hello team,

TPS1689 is not properly starting up if there is Rload of 15ohm.
(Customer has disabled TPS16851VMAR by populating R81 and R84.)

Setup Condition:
VIN: 43V
Load: 15ohm
dv/dt: 0.1V/ms

The startup waveform is below.
VOUT goes to 0V after 40ms.
What might be the problem here? Might it be thermal shutdown?

Can TPS1689 send fault status of thermal shutdown via PMBus?

Best Regards,
Kei Kuwahara

  • +1
    TI__Mastermind 36781 points

    Hello Kei,

    To protect the FET SOA, TPS1689 has 0.5A of start-up current (mentioned in EC table)

    Follow the AoA curve also in datasheet during start-up.

    That's why you see device failed start-up because thermal limit is reached.

    For your actual application, can you use PG to enable the downstream loads.

    Thanks 
    Amrit