I have a irf510 n channel fet which im using to switch the low side of the load of around 4 amps at 12v the problem is the fet is heating up too hot i have around 9v on the gate and the drain to source resistance is .4ohm which is rds(on) of around .45ohm according to the datasheet.Ive tried putting 12v on the gate still the fet is getting too hot,any ideas ?