If you’re not familiar with the 555 timer ... PWM applications are out. The MIC1557, on the other hand, combines TRIGger and THRESHold into a single “T/T” pin, and adds a chip select ...

As it turns out, the ever-useful 555 timer chip does the job admirably. It’s a simple enough circuit, the threshold pin is pulled high so the output goes high, and the PWM drive from an Arduino ...