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TPS1H100-Q1: Hard Short Circuit Current Limit

Kurt Schober
Prodigy 50 points
Part Number: TPS1H100-Q1

Hello,

I have been evaluating the TPS1H100-Q1 Evaluation Module (EVM)

My application is I want a high speed current limit circuit that that limits the hard short circuit current clamp to around 3.5 Amps consistently.

Currently using the EVM, and a 12VDC supply and current limit set to 2A. I apply short circuits randomly by basically scraping a stripped wire to the ground pin and occasionally the current limit allows up to 10A+ before the current is clamped. I am using a high speed scope with a tektronix current probe model A622.

It does this both when no load to hard short circuit is applied and 2A load to hard short circuit.is applied.

The reason that i want to limit the clamp current to 3.5A is that there will be no sparking at the shorting point.

Am i using the right part? or should i look at some other device.

Do you have any suggestions?

  • 0
    TI__Guru** 105361 points

    Hi Kurt,

    Welcome to E2E!

    Can you share your application use case and end product details to suggest appropriate device.

    In meanwhile, please go through the 1st chapter in http://www.ti.com/lit/ml/slyy168/slyy168.pdf to get a feel on the type of devices we have for protection based on the use case.

    BR, Rakesh

  • 0
    Prodigy 50 points

    Hello BR, Rakesh,

    The end product will be a portable 12VDC @2A Power Supply

    Regards

    Kurt Schober 

  • 0 in reply to Kurt Schober
    TI__Genius 12410 points

    Hello,

    Figure 49 in section 8.2.3 of the datasheet shows the fast trip response of the hard short to ground where the current goes higher shortly but the response of the device is typically 1us.

    Is this the type of behavior that you are doing?

    Also how much inductance are you introducing when you are shorting?

  • 0 in reply to Cameron Phillips
    Prodigy 50 points

    Hello Cameron,

    Thanks for your reply.

    Haven't got any inductance in the circuit. Just using the EVM with a short wire from output to the ground.pin.

    I have noticed though that when applying a hard short to the output the input supply drops by about 3 to 4V.

    Using a high current power supply with the current limit set to around 20A.

    How do i insert a screen shot of my scope so that i can illustrate the problem better?

    Regards

    Kurt 

  • 0 in reply to Kurt Schober
    TI__Genius 12410 points

    Hello,

    If you go to the reply page you should be able to insert media into your posts. However, if you would rather you can email me directly at c-phillips@ti.com the oscilloscope pictures so I can get a better understanding of what you are seeing on the EVM with a short circuit.

  • 0 in reply to Cameron Phillips
    Prodigy 50 points

    Hello Cameron

    Channel 1 = Current 2A/Div - Probe is 100mA/A

    Channel 2 = Volts 5V/Div

    As you can see the current limit control loses control when the input voltage to the device drops. As can be seen the voltage drop is quite significant.

    Regards

    Kurt Schober

  • 0 in reply to Kurt Schober
    Prodigy 50 points

    Hello Cameron,

    Not sure if you received the above.

    There was one typo.... Channel 1 = probe = 100mV/A 

    I have a question as well to do with the CL, currently set to 750 Ohms via the trim pot on the EVB.

    Monitoring the CL pin With respect to the actual hard short circuit current with the scope, seems indicate that CL reacts to a hard short circuit quicker than the internal FET switching, is that correct?

    Regards

    Kurt Schober