Interleaved boost PFCs are a more efficient and complex option than the traditional boost PFC. The interleaved boost PFC offers improvements to system efficiency, but at the cost of additional components. The gate driver requirements for an interleaved boost system are very similar to that of the boost system, except an additional channel is needed for the second MOSFET. To drive the two MOSFETs required for this topology, a dual-channel low-side gate driver such as the UCC27624 is often used. Figure 2-2 shows an example of an interleaved boost circuit.

Figure 2-2 Interleaved Boost Converter PFC With Parallel Boost Converters and a Diode Rectifier Bridge

Overall, by interleaving two boost circuits into one interleaved boost PFC there is a reduction in electromagnetic interference (EMI) and the boost inductor size. However, this comes with the tradeoff between a reduction in inductor size or a reduction in switching frequency. Reducing the switching frequency can help reduce the size of the EMI filter, but requires a larger inductor which increases magnetic volume. Also, the root mean squared (RMS) current in the boost capacitor is greatly reduced due to interleaving, but with that comes added cost and complexity.

The UCC27624 is often used in interleaved boost PFC circuit designs. The UCC27624 is dual-channel to account for driving both MOSFETs and is a non-isolated low-side gate driver. The UCC27624 can drive the high power MOSFETs that are used in the interleaved boost topologies due to the high output current capabilities of 5A sink and 5A source and is 30V rated. This driver’s propagation delay of 17ns and delay matching of 1ns as well as the rise time of 6ns and fall time of 10ns on the output channels helps to achieve the maximum efficiency that is required of these systems. UCC27624 also features UVLO and a -10V tolerance on the inputs for increased system robustness.