The gate driver is used to control the external N-Channel MOSFET by setting the appropriate GATE to SRC voltage.

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

• The EN/UVLO pin voltage must be greater than the specified input high voltage.
• The VCAP to VS voltage must be greater than the undervoltage lockout voltage.
• The VS voltage must be greater than VS POR rising threshold.

If the above conditions are not achieved, then the GATE pin is internally connected to the SRC pin, assuring that the external MOSFET is disabled. After these conditions are achieved, the gate driver operates in the conduction mode enhancing the external MOSFET completely.

The controller offers two gate drive variants. LM74502 with typical peak gate drive strength of 60 μA is suitable to achieve smooth start-up with inherent inrush current control due to its lower gate drive strength.

LM74502H with its 11 -mA typical peak gate drive strength is suitable for applications which need faster turn on such as load switch applications.

LM74502, LM74502H SRC pin is capable of handling negative voltage which also makes it suitable for load disconnect switch applications with loads which are inductive in nature.