The MOSFET being used to interface a CMOS logic system to a lamp rated at 24V, 12A.
An extract from the datasheet for the MOSFET is shown below:
VGS /V (max)
ID /A (max)
PTOT /W (max)
gM /S (typical)
rDSON
15
15
90
1.2
0.15
(a) Calculate the minimum value of VGS required to enable the lamp to operate at its rated current.
(b) Calculate the power dissipated in the MOSFET when the lamp is operating at its rated current.
(c) The maximum output current available from the logic system is 30mA. Explain why an NPN transistor would be unsuitable for this application.