Switching Regulators - Do they need filter inductors?

[sam_thornley]

I try to avoid using linear regulators in battery powerd portables. So I built a MC34063 switcher on some perf board to supply +5v to a Genesis 3 board. Works fine but it ended up too big to fit into my case. So i picked up some sample PTH08080's set to supply my +5v. As they are nice and small. The datasheet for the MC34063 says for digital circuits use a 1uH inductor on the output.

So my question is do other switching regs like the PTH08080 need a filter inductor on their output? Or can i just hook it stright up?...like most people do for powering their N64's.

I just don't want a constant faint pwm whine on my audio.

[Mario]

Check out the datasheet for the PTH08080. I think it says a 100uF cap on the output will help with that.

[sam_thornley]

Thanks Mario, i totally forgot about that optional 100uf capacitor on the data sheet. So i set my PTH board to +5v with a 300ohm resistor, added my two 100uf caps wired it up to my genesis 3 board. All works perfectly with no audio interference or anything . I just didn't realise how nice clean and stable those PTH08080 regs are. I've had regulators in the past that produce a dirty/squeaky pwm output.