The synchronous buck converter is a common DC/DC converter used in HVAC systems, and are also used in HVAC end equipment, such as thermostats, controllers, and sensors. Synchronous buck converters increase efficiency by replacing the diode referenced to ground in a regular buck topology with a switching power device. This DC/DC converter topology uses a switching power device on the low-side and high-side, requiring a half-bridge driver. Figure 4-1 shows an example of a synchronous buck converter.

Figure 4-1 Synchronous Buck Converter with UCC27301A-Q1

The UCC27311A-Q1 can be used to drive the switching power devices in a synchronous buck converter. The driver has a high drive strength of 4.5A peak source current and 3.7A peak sink current. This high drive strength allows for a fast rise and fall time, which reduces switching losses and ultimately increase the efficiency of the switching converter. The UCC27311A-Q1 also has negative voltage handling on the input pins for added robustness. The UCC27301A-Q1 is a similar driver to the UCC27311A-Q1, but has interlock for added protection against cross-conduction. Both the UCC27311A-Q1 and UCC27301A-Q1 have an integrated bootstrap diode.