As automobiles advance technologically, manufacturers are integrating more features for driver and passenger convenience and safety. One of these components of the body electronics and lighting system includes smart glass for the sunroof, sun visors, side windows and the driver’s Heads Up Display. In many of these applications, a Polymer Dispersed Liquid Crystal (PDLC) glass is used. These PDLCs typically operate with an excitation voltage of 40Vac to 80Vac, making PDLCs a potential candidate for a 120V half-bridge gate driver. Figure 2-7 shows an example of a PDLC smart glass block diagram.

In these PDLC smart glass systems, the power stage uses an H bridge with an LC filter to create the waveform needed to power the PDLC at 50Hz to 60Hz. This is done by switching at 100kHz to 500kHz with a PWM signal controlled by the MCU. To achieve high switching frequencies, a half-bridge driver with fast switching characteristics is needed. The UCC27282-Q1 features fast switching capabilities with 16ns typical propagation delays and 1ns of typical delay matching abilities. The UCC27282-Q1 also is capable of 12ns rise times and 10ns fall times with a 1nF load. Figure 2-8 shows an example of the H-bridge configuration in the PDLC system utilizing two of the UCC27282-Q1.