The gate driver is used to control the external N-Channel MOSFET by setting the GATE to ANODE voltage to the corresponding mode of operation. According to the ANODE to CATHODE voltage, there are three defined modes of operation that the gate driver operates under: forward regulation, full conduction mode, and reverse current protection. Forward regulation mode, full conduction mode, and reverse current protection mode are described in more detail in the Regulated conduction Mode, Full Conduction Mode, and Reverse Current Production Mode sections. Figure 8-2 depicts how the modes of operation vary according to the ANODE to CATHODE voltage of the LM74703-Q1. The threshold between forward regulation mode and conduction mode is when the ANODE to CATHODE voltage is 50 mV. The threshold between forward regulation mode and reverse current protection mode is when the ANODE to CATHODE pin voltages are –11 mV.

Figure 8-2 Gate Driver Mode Transitions

Before the gate driver is enabled, the following three conditions must be achieved:

• The EN pin voltage must be greater than the specified input high voltage.
• The VCAP+ to VCAP– voltage must be greater than the undervoltage lockout voltage.
• The ANODE voltage must be greater than V_ANODE POR rising threshold.

If the above conditions are not achieved, then the GATE pin is internally connected to the ANODE pin, assuring that the external MOSFET is disabled. Once these conditions are achieved, the gate driver operates in the correct mode depending on the ANODE to CATHODE pin voltage.