AOD448 is 30V? 75A tube, driven by 4.5V, a little high.
Lamp tubes such as AOD442, AO34 16 can be used, and the voltage can be driven by 2.5V, which is only 26 ohms. The current is 2 to 3 amps. No problem.
You can also use IRF540N, 1A, which is no problem at all. At that time, as a precision constant current source, the accuracy could be controlled to 1mA. But heat dissipation is very important. There should be enough heat sinks and small fans. A voltage of 3-5V is enough. High level drive (actually equivalent to PWM).
Extended data:
MOS tube switch circuit:
1, p-channel MOS transistor switching circuit
Due to the characteristics of PMOS, when Vgs is less than a certain value, it will turn on, which is suitable for the case that the source is connected to VCC (high-side drive). It should be noted that Vgs refers to the voltage between the gate G and the source S, that is, the gate turns on when it is lower than the power supply by a certain voltage, not the voltage relative to the ground. However, due to the large internal resistance of PMOS, it is only suitable for low power. N-channel MOS tube is still used for high power.
2.n-channel mos transistor switching circuit
The characteristic of NMOS is that it will turn on when Vgs is greater than a certain value, which is suitable for the case of source grounding (low-side driving), as long as the gate voltage is greater than Vgs given in the parameter manual, the drain D is connected to the power supply and the source S is grounded. It should be noted that Vgs refers to the voltage difference between the gate G and the source S. Therefore, when NMOS is used as a high-side driver, when the drain D and the source S are connected, the potentials of the drain D and the source S are equal, so the gate G must be higher than the voltage of the source S and the drain D before the drain D and the source S can continue to be connected.
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