I am using this LDO to step down from 14V to 5V with a maximum output load current of 150mA.
The above is the schematic of my LDO. I want to measure the inrush current of the LDO.
But since I have an output capacitor of 1uF, I think the output capacitor will also contribute some inrush current.
I want to understand about inrush current. I have read and understood that the inrush current is caused by uncharged capacitors getting charged during start-up. Hence, the high inrush current during starting of the power supplies.
Question 1 :
My 1uF is placed at the output. So, when I need to measure the inrush current of the LDO, should I measure the current at the input pin 1 of the LDO or at the pin 8 of the LDO during start-up? (I think both scenarios are not that different, since in LDO, the input current is same as the output current as LDO just has an internal pass MOSFET or transistor- Am I correct?)
I have a doubt in this too. To measure the exact inrush current, should I take a wire (very low resistance) from the output pin 8 of the LDO and connect it to the 1uF capacitor and measure the current through this wire using a current probe and note it down as the inrush current? Is this approach correct?
Question 2 :
In DC-DC converters, for example, buck converters, say TPS54260, the input inrush current and output inrush current are different, right? In this case, how to measure the inrush currents at the input and output?