scr gate resistor choice

[yougarage]

Hi!
I need to drive a SCR with a microcontroller, so I' figuring out which gate resistor to use.
The scr is a BT151, the datasheet shows a typical gate trigger current of 2mA to 15mA max.
The microcontroller has 50 mA push pull capability.
Based on these data, a 220 ohm resistor should give about 22mA gate current.
Are my calculations right?
Can I avoid using a gate pulldown resistor because the mcu has push pull output?

 

[crutschow]

The data you didn't include in your resistor calculation is the SCR gate input voltage.

Yes, you shouldn't need a gate pulldown resistor if the output is push-pull.

 

[yougarage]

You are right, the gate trigger voltage is 0.6 v typical, 1.5 max