A softer start with an IRLZ44N
The LED bench lights and controller I built awhile back has been going well, excepting a bit of inrush current when I turn on the AC/DC converter.
Great Scott did a video and great explanation for a circuit to address this problem, using a Solid State Relay (SSR) and a few simple components to throttle the inrush from an inverter.
The issue for me and using his circuit is that I don't want to make a soft starter for an AC device (inverter), but rather a DC device (LED lights).
The SSR and Great Scott's circuit will work (despite the online naysayers), but will just latch the LEDs once when it has soft started the circuit, which is in truth all I need it to do. When it is not being used it is turned off - I don't turn it on and off during use.
Despite that, and because I'm a bit quirky at times, I wanted to try another avenue and so I designed via the simulator an analogous DC appropriate circuit built around the IRLZ44N N-channel Mosfet.
A Mosfet is voltage activated, not current activated like a BJT, and so I used a couple of 100k resistors in a voltage divider configuration to reduce the 20V coming in from the AC/DC converted to just 10V. According to the data sheet, the IRLZ44N should then be wide open!
The 10V is then channelled via an RC circuit to the gate of the mosfet. The RC combo gives the time it takes for the mosfet to fully open according to these calculations.
After a quick prototype and some testing of this simple little circuit in situ I soldered it all up on a PCB and shoved it into the LED supply box - and it works!
I probably should have spent some time looking into the horrible hot glue mess for the display, but...quirky!
No comments:
Post a Comment