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LM51561: RSL

Part Number: LM51561

Hi,

RSL is restricted under 1kΩ on the app note as below;

https://www.tij.co.jp/jp/lit/an/snva866/snva866.pdf?ts=1617326502422&ref_url=https%253A%252F%252Fwww.tij.co.jp%252Fproduct%252Fjp%252FLM5156

What is this restriction caused by?

Best Regards,

Kuramochi

  • Hello Kuramochi,

    The maximum value for RSL is in LM51561 2 kohm.

    Best regards,
    Brigitte

  • Hi Brigitte-san,

    Thank you for your reply.

    What is the 2kΩ limit caused by?

    Best Regards,

    Kuramochi

  • Hello Kuramochi,

    Please have a look at Figure 8-5 in the datasheet at page 9. As you can see, the current limit is with the external RSL resistor dependent on the duty cycle and if you see the slope of this dependency with a 1 kohm resistor, a value bigger than this makes the current sense signal measurement very inaccurate and extremely dependent on this resistor. So I would even say that keeping this resistor below 1 kohm makes sense.

    But if the customer wants to use even higher resistors, this is possible, but most probable, at higher duty cycles no output current will be available.

    Best regards,
    Brigitte