Most of the definitions of "active" components that I have found define them as components able to control current flow. A switch fits this definition, but I am just curious to see opinions on this.
Electronic – Is a switch considered an active component
switches
Related Solutions
You can just use the PMOS, and use a pin switched from output low to high impedance (e.g. input) to switch it on/off:
The 10kΩ resistor holds the FET off when the ON-OFF signal is left floating (i.e. your pin is an input/high impedance)
Then when the pin is driven low, the gate is pulled to ground and the FET turns on. You need to make sure the P-ch MOSFET you use has a suitably low Vgs(th) (turn on voltage threshold - some can be quite high) so you want a "logic level" MOSFET.
Simulation:
There are some issues with using extremely high frequencies to switch LEDs: The LED junction capacitance becomes a factor, and intensity drops significantly as the LED does not get the required excitation time per pulse.
LEDs have a minimum rise time specified, refer to the datasheet of the LED concerned to determine yours.
In other words, the light will be dimmer than at lower frequencies, and PWM dimming will be much less linear than with lower frequencies.
Assuming that the frequency for controlling the LED can be dropped much lower, an alternative approach is to use a high current rated latching serial-in-parallel-out power shift register like the Texas Instruments TPIC6A595.
This shift register has a high enough current rating, 350 mA per channel, to be able to sink the 200 mA per LED load described. What it lacks is the speed to handle the 120/125 MHz signal rates mentioned in one of OP's comments.
The benefit of this approach is that it requires a small number of control pins from your controller, and since the device is cascadeable, increasing the LED count does not increase required pin count.
If an even higher current drive is required, it is simple to drive two MOSFET arrays like the Hitachi 4AK21 from each shift register. This array is rated at 8 Amperes per channel (so long as per-channel dissipation is under 4 watts across Rdson=0.12 Ohms).
Best Answer
A switch is a passive component.
The main difference between active and passive, is that active components require a power source to perform their function, i.e. using electricity to control electricity as in a transistor. They can be a source of power in the circuit or provide an electrical switching function. They can provide amplification, whereas a passive component cannot.
So Valves(Tubes), Transistors, SCRs, LEDs, Diodes, ICs, etc are all active devices.
Passive devices are things like Resistors, Capacitors, Inductors, Transformers, Thermistor, Speaker, Microphone, etc.
To be honest I think the definition is a bit muddy, and I've never seen a formal definition that satisfies me completely, but the above is the usual sort of answer. For example, take the diode - this often causes a bit of debate on how it should be classified (I think it probably has to be an active device) Either way I think it doesn't really matter much as long as you get the general idea.