16.5.2.8.2 Output Override Behavior in Complementary Output Mode with PWMxL’s Max On-time Adjustment

In many topologies, PWMxL is used to control a synchronous rectifier switch which allows the power filter to freewheel during the off time. While in Discontinuous Conduction mode, however, it may not be desirable to keep the fully synchronous operation or completely turn off using FET body diodes for rectification. A better way to emulate diode operation is by actively driving the FET during the conducting phase and turning it off when the switch current crosses zero. This technique is common and widely used as an effective efficiency enhancement. With increasing CPU performance, low-side on-time estimation can be implemented in firmware to eliminate the need for external circuitry, thus reducing the additional analog peripherals. The PGxTRIGF register is, therefore, allocated to provide for this functionality. By properly programming this register, the PWML’s on-time is turned off upon its trigger event.