Inverting Output DC-DC Regulator Options

[pacmann]

I want to find a inverting output dc-dc regulator that I can get assembled from JLCPCB with output of -18v, 150 mA max in my circuit. My input is 5v.
NCP3063 is supposed to be newer version of MC33063 but is not stocked. Is there a regulator better or more efficient than MC33063 for this circuit?

Thx!

[T3sl4co1l]

Use a Cuk converter, any boost/flyback regulator will do.  Only some support negated inputs so you'll need to add an inverting op-amp to get the correct feedback polarity.

CS5171 family comes to mind.

Tim

[pacmann]

Thanks. What determines the max output current for the CS5171? Its has a 1.5 A switch but their example circuit only shows 75 mA output current.

[mariush]

They have MC34063ADR2G available nearly 50k+ parts :  https://jlcpcb.com/partdetail/Onsemi-MC34063ADR2G/C32078
if it does 150mA or not... not sure. There's online calculators or formulas in datasheet you can use.

*33063 is also available but you'll have to be careful here... unless I'm confusing it with some other code, I think some 33063 chips don't support inverting, only buck/boost.

[T3sl4co1l]

Thanks. What determines the max output current for the CS5171? Its has a 1.5 A switch but their example circuit only shows 75 mA output current.

That's a charge pump circuit, not a switched inductor circuit.  Possibly that's as much current as can be sunk through the output capacitor (follow the diodes).

Cuk uses two inductors, preferably coupled, and has dynamics same as any boost/flyback.

Tim

[Faringdon]

Here is a cuk with neg output in LTspice the free sim...