I am considering some new alternatives for a circuit that sends a slow Arduino PWM signal to a SSR which controls an electric heating element.
Right now, the circuit consists of a low side switch with NPN transistor (2N3904). That configuration is fine for many situations, but sometimes the output is used for something besides driving a SSR. In those instances it would be more convenient if the load were tied to ground and the 5V side were switched.
So I am looking at a high side switch instead. Right now I have the replacement circuit tentatively drawn with a PNP (2N3906) and 1K current limiting resistor between the gate and Arduino pin D10 (see attachment). (Note, there are obviously two outputs shown in the figure, but I will arrange them both the same).
Would an IRLML5203 p-channel be a suitable replacement for the 2N3906? As the figure shows, it has to carry max. 200mA.
If I use a p-mosfet, I (think I) know that the current limiting resistor isn't needed between D10 and the gate. But do I need a pullup to keep the gate high until D10 is done being configured as an input? Is there any other reason to have a pullup on the gate?
Any suggestions about a more suitable mosfet, and/or circuit configurations would be really appreciated.