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TPS25947: Input Voltage Range

Ede Caldeira
Prodigy 70 points
Part Number: TPS25947
Other Parts Discussed in Thread: TPS2640, TPS2660

Tool/software:

Hi team,

I want to use eFuse TPS259474LRPW in our application to monitor the voltage of a pure resistive load (~1.7 amps).

The response to fault is latch-off and I want to mainly use the eFuse to monitor the voltage input voltage and disable the load if the input voltage goes above 20V. 

There are 2 possible conditions:

Input voltage is 17V = eFuse is on, load is powered.

Input voltage is 24V = eFuse detects overvoltage (>20V), latches-off, load is off.

The input voltage of 24 V can be sustained for long periods of time - (e.g. 30 days).

My question is around the recommended operating voltage (23 V), and the absolute maximum voltage (28V).

The 24 V of our application is within the absolute maximum, however it is above the 23V recommended.

I would like to understand why 23V is the recommended voltage and if the limitation of the part under this condition is applicable to my application:

- Is this 23V a number based on the maximum power dissipation under clamping mode/active current ? (this will not be the case for my application, then the 1V extra won't be a problem).

- Or is it a limitation of the breaking down voltage of internal circuitries and long-term reliability?

- Is it okay to have 24 V applied permanently with the overvoltage lockout protecting the load permanently?

Thank you.

Ede.

  • +1
    TI__Mastermind 39315 points

    HI Ede,

    Ede Caldeira said:
    - Is this 23V a number based on the maximum power dissipation under clamping mode/active current ? (this will not be the case for my application, then the 1V extra won't be a problem).

    During the OV lockout state, the HFET will see this voltage across it. Since this voltage level is under the abs max voltage, the FET won't get damaged. During this state, we also don't expect any current path so other than uA leakage current, we won't have any other current. This means the power dissipation and thermals should not be any issue. Based on this, I don't expect any damage to the device in this state.

    Still this is more than recommended max of device so the device will have more stress on it and may show higher fails over lifetime. I can recommend TPS2660 or TPS2640 which are industrial eFuses with 60V abs max.

    Ede Caldeira said:
    - Or is it a limitation of the breaking down voltage of internal circuitries and long-term reliability?

    Internal circuitry is rated for higher voltage then voltage seen in your application. I don't see any concerns by design but the qual test is done only till recommended max so my primary concern is long term reliability. 

    What is your end application? If the long term reliability is of concern then I would recommend not to cross the recommended max of device.

    Best Regards,
    Arush

  • 0 in reply to Arush Gupta
    Prodigy 70 points

    Hi Arush,

    Thank you very much for your quick response. And thanks for recommending the other 2 options.

    My application is medical, unfortunately I cannot disclose any further details in this public forum.

    Your answer helped me a lot. Thanks.