# Do all switching converter ICs support multiple topologies?

I'm trying to design a low-noise power supply for small-signal audio (+/-12-15V, ~1A). As part of this, I'm investigating advanced SMPS topologies like the SEPIC and Ćuk converters. Few controller/converter ICs mention support for these topologies in their datasheets, and the ones that do (such as the LM5001) seem to support a more common topology as well, usually boost. I also found an EE Times article on how to design a negative buck converter using a boost converter IC, and an app note that implements a buck-boost converter using a buck converter IC. What I have not found is a general list of which topologies are supported by each type of controller/converter. Thus, I have two questions:

1. Can all converter ICs be used to implement multiple topologies?

2. If so, which topologies are supported by each type of basic converter IC (buck, boost, etc.)?

## 1 Answer

An SMPS controller1 IC may support multiple converter topologies. But a single IC almost never supports all common converter types.

There is a family of converters derived from boost converter: flyback, SEPIC, boost proper. A controller that can do boost, usually can do the rest of the boost family too. Usually, one controller can't do both buck family and boost family.

1 SMPS controller IC drives external power switches. SMPS converter IC has power switches on board. Converter ICs tend to be less versatile than controllers.

• So the difference in transfer functions doesn't matter? – Adam Haun Feb 22 '16 at 21:06
• Closed loop feedback adjusts to transfer function ( $\frac{1}{1-D}$ for boost vs. $\frac{D}{1-D}$ for SEPIC ). Although I suspect that feedback loop compensation (external to the IC) may be different. – Nick Alexeev Feb 22 '16 at 21:28