So the switch-mode constant current drivers shouldn't be pwm'ed?
So are you saying the ZTX851 would be better to use than a logic level mosfet but still not better than getting a constant current source with a dedicated pwm pin?
Can I build this circuit instead of buying a different pwm constand current driver?
ZTX851 isn't a good part. The drive requirement for 300ma Ic is quite substantial for a mcu, and if you cannot deliver that much current, you see Vce going up and power dissipation up.
According to his formula to find the resistor value for R3 I should be using a 1.5ohm resistor, do these exist?
Yes. Don't forget that the resistor will be a little heater, too. At 350mA it will produce over 1/2 a Watt of heat. I'd get at least a 2W resistor to give it a chance of not burning your fingers.
Please enter a valid email to subscribe
We need to confirm your email address.
To complete the subscription, please click the link in the
email we just sent you.
Thank you for subscribing!
via Egeo 16