LM7310: How to calculate soft-start when added a series resistor to CdVdt

Tamio Yokokura

Part Number: LM7310

Hi, LM73100 support team

In LM73100EVM schematic, a series resistor is added to a capacitor on dVdt pin. This series resistor is not considered in Design_Calculator. In this case, how to calculate the soft-start time?

Regards,

Tamio

over 2 years ago

0 Kunal Goel over 2 years ago

TI__Guru* 79181 points

Hi Tamio, Formula will remain same with and without resistor.

Regards

Kunal Goel

0 Tamio Yokokura over 2 years ago in reply to Kunal Goel

TI__Expert 3960 points

Hi, Kunal

I understood that the same formula can use for without a resistor. By the way, what purpose is a series resistor?

Thanks

Tamio

0 Kunal Goel over 2 years ago in reply to Tamio Yokokura

TI__Guru* 79181 points

Hi Tamio,

It is for limiting current through a FET between dvdt and VOUT. There is switch that short dvdt to VOUT after startup is complete.

Regards

Kunal Goel

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LM7310: How to calculate soft-start when added a series resistor to CdVdt