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TPS2660: TPS2660 Inrush current shutdown problem

udhay kumar
Intellectual 295 points
Part Number: TPS2660
Other Parts Discussed in Thread: TPS2663

I'm using TPS2660 for an optional parallel connected power supply design with a input voltage of 24V and 500mA (max) average current. Vuv=20V, Vov=28V and current limit is 1.93A (6K2 resistor)

I don't know the inrush current value of the load, but the TPS2660 keep on resting the output due to Inrush current for any value of dv/dt capacitor.

I need to know is there anyway to disable the inrush current limit function permanently?

  • 0
    TI__Guru** 105361 points

    Hi Udhay,

    Thanks for considering TPS2660 in your design.

    What is the Cout and the actual load. ? Can you share the filled up TPS2660 design calculator for review. It is available under TPS2660 product folder.

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Intellectual 295 points

    Hi Rakesh,

    Thanks for the speedy response.

    Unfortunately I don't have the precise answer for your question. This power supply is designed to use in a 19" rack module. We have variety of add-on boards in the maximum possible of 13 rack slots. Every board has different kind of filter capacitor value and loads. Example we have 4 relay cards with 4x8= 32 relays and the power on state condition will be vary every time. The average current is not exceeding 700mA at now.

    I can clearly understand, its very difficult to calculate the inrush current for this kind of load. Unfortunately I don't aware of the design tool of Ti, so I did all the calculation by myself and tested it at steady state condition. Only thing bothers me is the inrush current which I can't reduce to below the set current.

    So this is the reason I like to know is the any option to disable the inrush current limit function permanently?

    If no, please suggest any other option if you have. I've identified few IC's like LM5050 & LM74700 with no additional functions like OVP & OCP. At worst case I can go for that, but before I would like to get suggestion from you.

  • 0 in reply to udhay kumar
    TI__Guru** 105361 points

    Hi Udhay,

    Please test again by leaving dVdT pin open. This allows device to start in current limit mode and may help in your case.

    The other option is TPS2663. The device has thermal regulation loop and helps to start unknown loads. Please refer app note 

    https://www.ti.com/lit/an/slvaeb9/slvaeb9.pdf 

    Best Regards, Rakesh

  • 0 in reply to Rakesh
    Intellectual 295 points

    Dear Rakesh,

    Please excuse me for the delayed response. I'm not able to reply in time due to our long festival holiday.

    I'm very glad to accept your recommendation TPS2663. As you suggested I tried with TPS2660 with open dv/dt pin, but still in most of the time the supply going to hiccup.

    As I can understand from the datasheet, TPS26631 is suitable for my requirement with 2x pulse current support. I would like to receive your suggestion on this.

    I tried multiple time, but I can't get the free samples from TI, may be TI stops sample support. I feel very happy if you can help me to get few free samples for our testing. I know that this not the place to ask for the samples, but there is no other way and no response for sample request from TI.

  • 0 in reply to udhay kumar
    TI__Guru** 105361 points

    Hi Udhay,

    Can you share test waveform for TPS2660 with dv/dt pin OPEN.

    For sample related questions, can you please submit request at ticsc.service-now.com/.../

    Best Regards, Rakesh