I may be re-inventing the wheel, but haven't come across this circuit before for generating PWM pulses using an absolute minimum of components; just one CMOS Schmitt gate (e.g. CD40106, CD4093, 74HC14) and four passives :-

It can generate duty cycles voltage-controlled from ~ 10%-90% (your mileage may vary, depending on the Schmitt hysteresis). The penalty for simplicity is that the pulse frequency varies, at 50% duty-cycle being about twice the frequency at 10% or 90%. For many applications, e.g. LED dimming and motor speed control, such variation is unimportant.
Enjoy!

 

Nice little circuit. One thing - for any particular control voltage value, both the frequency and pulse width percentage vary with the temperature of the chip die, and vary from one chip to another. As you say, there are applications where this doesn't matter, but it is something to keep in mind.

ak

 

I like that circuit.
Can't get much simpler than that to generate a PWM signal for non-critical applications.