Re: Camtronics 5A Stepper Motor Driver Board - Power Supply Current Requirements?

Tim Goldstein wrote:

> That is a good question and I don't know the real answer. From my
> experience the input current draw is less than the total of what each axis
> is set for added together (3 axis's set at 5 amp each draws less than 15
> amp).

This is because a 'chopping' type stepper motor driver is really a special
case of a 'buck' (or step-down) switching power supply. So, the input
current (at higher voltage) is always less than the output current (at lower
voltage). So, if you are using a 5 V, 5 A stepper (that's 5 Amps for each
of 2 windings) and are in full step mode where both windings are always
energized, you have 5 x 2 = 10 A x 5 V = 50 VA or Watts out. If the
main power supply is 24 Volts, it draws I = P / V, or 50 / 24, or
approximately 2 Amps. Various losses in the chopper will cause the
current draw to be a bit higher. So, that is how 2 amps in can be turned
into 10 amps out.

Jon