SNOSDE5A December 2021 – May 2022 LM74502 , LM74502H
PRODUCTION DATA
The important MOSFET electrical parameters are the maximum continuous drain current ID, the maximum drain-to-source voltage VDS(MAX), the maximum gate-to-source voltage VGS(MAX) and the drain-to-source On resistance RDSON.
The maximum continuous drain current, ID, rating must exceed the maximum continuous load current. The maximum drain-to-source voltage, VDS(MAX), must be high enough to withstand the highest differential voltage seen in the application. This requirement would include any anticipated fault conditions. The maximum VGS LM74502 can drive is 13.9 V, so a MOSFET with 15-V minimum VGS rating must be selected. If a MOSFET with VGS rating < 15 V is selected, a zener diode can be used between GATE to SRC pin to clamp VGS to safe level.
To reduce the MOSFET conduction losses, lowest possible RDS(ON) is preferred. Selecting a MOSFET with RDS(ON) that gives VDS drop 20 mV to 50 mV provides good trade off in terms of power dissipation and cost.
Thermal resistance of the MOSFET must be considered against the expected maximum power dissipation in the MOSFET to ensure that the junction temperature (TJ) is well controlled.