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TPS25947: Protect issue

Bryan Chang
Prodigy 50 points
Part Number: TPS25947

Tool/software:

Dear Sir, 

The former answer from TI: 

When PD Adaptor plug in , TPS25947 is protected  

We can not understad that why does TSD trigger , the  TSD spec. Tj is 154 degree C 

And the max. inrush current is only about 4.41A  which is event smaller than O.C.P setting (6A) 

By the way we have another QA: 

1. What is the O.C.P delay time ? (When output current reach 6A remain how long then protect) 

2.  Will TPS25947 skip the inrush current protection which  duration is < 100us ? 

C1 EN

C2 CURRENT

C3 VIN

C4 VOUT 

Thanks and best regards,

Bryan 

  • 0
    TI__Mastermind 39315 points

    Hi Bryan,

    Bryan Chang said:
    We can not understad that why does TSD trigger , the  TSD spec. Tj is 154 degree C 

    Power dissipation across the device is Vin-Vout*I. Now here Vin = 20V but Vout is low. For example, during the startup, the Vin - Vout * Current will be 20V- 10V * 5A = 50W. If you check the time to TSD graph, device will go into TSD within 0.2ms. 

    Bryan Chang said:
    . What is the O.C.P delay time ? (When output current reach 6A remain how long then protect) 

    Will depend on itimer pin setting.

    Bryan Chang said:
    2.  Will TPS25947 skip the inrush current protection which  duration is < 100us ? 

    Here, it doesn't look like the device is shutting down and doing retry due to current limiting but rather due to TSD. 

    Best regards,
    Arush