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LM5069: Input/Output capacitor and diode

Kuramochi Tadahiko
Guru 28715 points
Part Number: LM5069

Hi,

My customer is considering to use LM5069 as current limit SW controller.

In this case, are input/output capacitors and diodes required?

If yes, what is important parameter to select these component?

Best Regards,

Kuramochi 

  • 0
    TI__Expert 5940 points

    TQ,

    You need a small Cin capacitor, 0.1uF placed at the Rsns + terminal, not at the Vin pin.  Cout is what ever your system capacitance is.  Go to www.ti.com/hotswap to download the latest design calculator tool to assist in component selection.  There are excellent tutotial videos and app notes located there also.

    Brian

  • 0 in reply to Brian Daugherty
    TI__Expert 5940 points
    TQ,

    Regarding the diodes, you refer to the input TVS and output Schottky I assume. Yes, you need those to protect against Vin overshoot and Vout undershoot when a fast FET turn off is peformed during a fault on the output. Vin will rise to the point of destroying the IC without a TVS and Vout pin can be damaged when Vout drops below ground.

    Brian
  • 0 in reply to Brian Daugherty
    Guru 28715 points

    Brian-san,

    Thank you for your help!

    I have additional questions.

    >at the Rsns + terminal,

    Could you show me the point of terminal in detail?

    I don't understand "terminal".

    > Go to www.ti.com/hotswap to download the latest design calculator tool

    I couldn't find the calculator tool on above URL...

    Is it exist on the below screenshot?

    Best Regards,

    Kuramochi

  • 0 in reply to Kuramochi Tadahiko
    TI__Expert 5940 points

    Kuramochi,

    Place the capacitor at the positive side of the resistor (current entering resistor), right at the pad.  This filters both sides of the resistor and prevents DM signal from triggering current protection and also prevents Vin - Vsns from exceeding the device rating of +/- 0.3v.  See figure 43 and the abs max table for further explanation. 

    The calculator tool is under the "Tools and Software" tab.

    Brian