Simple DC motor PWN speed control

[microzone]

      Recently I have read a Simple DC motor PWN speed control circuit from
http://www.electronics-lab.com/projects/motor_light/038/index.html. Inside the article and below the word of important, there have mention that "the drain (or collector) current must be equal to maximum motor current (at power supply voltage, when it is blocked)". May I know what is mean by maximum motor current? Can I check it from the data sheet (Which part of a data sheet, can you please guide me?) or measure from the 12V DC motor.  Thanks for your kind help

 

[audioguru2]

A permanent magnet motor has its max current when its shaft is stalled. When mechanically overloaded and when it begins to run. It also has a very high current at the moment its direction is reversed.
The max current is the supply voltage divided by the motor's resistance.

 

[ZomBiE]

And be sure that your speed controller can stand twice that "shot-circuit" current when testing. PWM is tricky in some situations.