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I think I can use this (TPS26623) part for my positive upply application but how about negative supply?

Bert Hennink24
Intellectual 335 points
Other Parts Discussed in Thread: TPS2662, LM5067, TLV431, TPS2399

I discovered this part which could inprove  the circuit in my aplicatiion  for positive supply.

I now use a current source to protect against wrong cable connection in the supply connection of my system.

This E-fuse like (TPS26623) could do this job in a smaller size and more efficient.

But Is there an application for use of Efuses in an negative supply rail?

For a current source circuit this is easy.

  • 0
    TI__Expert 8630 points

    Hello Bert,

    TPS2662 devices can provide protection from negative voltages on input or output. To operate with negative input voltage, negative hot swap devices like LM5067 would be suitable.

  • 0 in reply to Lokesh Ghulyani
    Intellectual 335 points

    Hi Lokesh,

    I am not looking for a hotswap device.

    I am searching for an electronic fuse for the negative branch of a symmetric supply

    And it needs also be capable of fusing at low currents (50mA)

    I know pretty hard requirement to meet. I can do it with a currentsource build around a 1.25V TLV431

    Problem is that I will loose about 2V and quite some boardspace.

    In the design there are also intrinsic safety requirements

  • 0 in reply to Bert Hennink24
    TI__Expert 8630 points

    Hello Bert,

    For current limiting or over load protection in negative supply voltage, there is no eFUSE suitable at present. LM5067 or TPS2399 with external FET would be suitable here for over current protection in negative supply rails.

  • 0 in reply to Lokesh Ghulyani
    Intellectual 335 points

    Hi Lokesh,

    Thanks for your response.

    These ar nice parts but will ik be able to creat e an accurate electronic fuse with it?

    I need to protect a physical fuse from tripping in fault condition.

    Example the physical fuse is rated 63 mA (safety requreed)

    The normal currcent from the load <40mA

    And the electronic fuse should limit the current an about 50mA (functional protection of the fuse)

    Could these devices perform with such accuracy?

    If I understand the DS the LM5067 has about 30% accuract and the TPS2399 20% or am I mistaking here?

    Greets,

    Bert

  • 0 in reply to Bert Hennink24
    TI__Guru** 105361 points

    Hi Bert,

    The current limit accuracy is +/-12% for LM5067. When the sense resistor drop exceeds the current limit threshold the device continues to power the load for a fault timer period set at the Timer pin. For you application, you can set very low timer value (10us to 100us) so that the path will break as soon as the current hits the current limit threshold instead of waiting for the circuit breaker trip.

    You can set current limit at 45mA (sense resistor = 50mV/45mA), so current will be limited between 39.6mA to 50.4mA. Please get an EVM and test as we never evaluated at such low currents.

    BR, Rakesh