Part Number: LMR23610
Hello,
I selected the LMR23610 regulator for a low current step-down application. This is a 1A-capable regulator. My load is light, typically about 50mA-75mA. The circuit looks like the reference circuits in the datasheet and the recommended circuits in Webench. Given my specs (Vin = 9-20V, Iout = 1A or less), Webench recommended component values and I used them to build a circuit. The input capacitors recommended by Webench have an ESR spec that goes as low as 2 milliohms, and there are two of these caps in parallel.
Circuit measurements show high inrush current (input current transient on power-on). Supplying 12VDC to the input, I see transient currents of 15A or higher in a roughly triangular shape that rises faster than it falls. The entire transient is about 100us from start to finish. I suspect that the ESR of these caps is responsible for this inrush.
Some questions:
1. Is the inrush likely caused by the low ESR of the input caps?
2. Is selecting a capacitor with higher ESR an effective strategy for reducing the inrush?
Thanks
Carl