Large instantaneous power supply draw

[jdhar]

Hi there,

I am designing a circuit, and using a 3A Switcher for my power supply. I am using an ultrasonic sensor that says it can draw up to 2A when active. How should I protect this from bringing the rest of my rails down? Is Bulk capacitance/series resistance good enough, or should I filter out my other devices more than just a simple decoupler?

 

[IanP]

To supply this sensor build a low-pass filter consisting of an inductor (≈100µH rataed for at least 2A) and after inductor a couple of capacitors: 100nF + 2000µF (1000µF per 1A, rated for voltage you use in this circuit) as de-coupling capacitors.

 

[jdhar]

Thanks Ian.. are there any resources you can point me to that show how you handle this stuff? I have seen some RLC filters before,but I don't know how to design around them.

 

[IanP]

Here you have some usefull links to power filters:
**broken link removed**
**broken link removed**

 

[jdhar]

Those are great links IanP, thanks a lot!