Product Description:

The 303 servo amplifier is produced by Copley Controls within the DC Servo Amplifiers series. The module conditions command inputs and delivers controlled bidirectional current to DC motors, allowing tight velocity and position loops in industrial automation. By converting reference voltages from a motion controller into pulse-width-modulated power, it serves as the interface between low-power control electronics and electromechanical actuators on conveyors, pick-and-place heads, and similar axes.

At the analog front end, the current monitor produces 2.0 A/V, letting external controllers read actual motor current without isolation stages. Command scaling aligns with a normal output level of +5 V across a 1.87 kΩ source, while a reset pull-up of 100 kΩ establishes a logic-high state for the fault line. Power is switched at 22 kHz, a frequency that keeps ripple outside most servo bandwidths and works with the amplifier’s small-signal bandwidth of 3 kHz. The output bridge presents only 0.26 Ω of resistance. The rated load inductance is 250 µH, so the internal servo preamplifier gain of 210 helps maintain stable current regulation without audible noise.

Continuous operation is allowed until the chassis reaches 83 °C, after which shutdown is initiated. For high-demand moves, peak current can be supplied for one second in unipolar mode before foldback reduces the drive output. The R8 network uses a 10 kΩ resistor to set the maximum current threshold. Load matching assumes a motor resistance of 2.5 Ω in conjunction with the rated inductance. During saturation, the bridge has a voltage drop of only 3.12 V, conserving the available bus voltage. The amplifier disables if the supply rails fall to 16 V. Speed feedback scaling pairs an 8 V tachometer signal with a 10 V reference, keeping velocity loops linear and allowing the controller to respond consistently to changes in motor speed.