Will it work ??

Hi All ,

I'm wondering , will this circuit be able to drive a stepper motor 3 A ? actually i tried to find this detail in the datasheet of Tip 122 but couldn't find it .

please help me

https://www.imagesco.com/articles/picstepper/03.html

watzmann

The TIP120/TIP121/TIP122 NPN Epitaxial Darlington Transistors data sheet states Collector Current (DC) 5 A for continuous so I don't see why it won't drive 3 amps pulse to stepper motor coils. The pulse current rating is 8 amps.

Ron

The TIP122 has a max saturation voltage loss of 2.0V at 3A when its base current is 12mA.
But the CD4050 cannot source 12mA when its supply is only 5V, its minimum source current is only 3mA. It needs at least a 10V supply plus series current-limiting resistors.

EDIT:
You know what? The CD4050 is not needed because the PIC has plenty of output current. Then there must be 150 ohm current-limiting rersistors from an output of the PIC to the base of the TIP122.

Contrary to what the author says, the diode built in to the TIP122 will not protect it from inductive flyback. The diode needs to be across the coil, cathode to +V.