Product Description:

The 4212D is a single-axis amplifier produced by Copley Controls for its DC Servo Amplifiers series. It drives torque-controlled DC servo motors in automated machinery by converting a regulated DC bus into pulse-width-modulated current that follows a controller’s command. Through its PWM/Dir interface, the unit accepts direction and duty-cycle signals from motion controllers, allowing compact velocity or position loops to be implemented in industrial robots, pick-and-place heads, or material-handling axes.

The amplifier can source up to 6 A of continuous motor current, which is sufficient for medium-frame servomotors that perform sustained work without overheating the drive stage. For acceleration or disturbance rejection, it supports a peak current of 12 A for brief intervals, providing extra torque before current limiting engages. The power section works with supplies as high as 125 VDC, so it can be connected to common 24–120 V battery or bulk supplies while keeping the switching devices within their ratings. Internally, the transistors commutate at a PWM switching frequency of 25 kHz; this ultrasonic rate minimizes audible noise and lowers ripple current in the motor windings. The current loop has a bandwidth of 3 kHz, allowing the amplifier to track fast command changes and reject load disturbances in multi-kilohertz servo systems. A 100 percent modulation range allows the full bus voltage to appear across the motor when the duty cycle reaches its limits, maximizing its speed potential.

The unit remains operational down to 22 VDC, permitting low-voltage startup or battery sag without triggering an undervoltage fault. Motor inductance can range from 200 µH up to 40 mH, providing flexibility when the drive is paired with different coil designs. An internal sensor trips at 70 °C to protect the power devices, and the control circuitry automatically reenables the output after a 200 ms self-reset interval if the fault clears. The ±15 VDC auxiliary outputs can power encoders or external signal-conditioning devices, while the ±6 V current monitor and reference outputs mirror instantaneous motor current for analog feedback to host controllers. The aluminum case measures 3.0 × 4.3 × 1.0 inches and can be bolted to panels that provide the heat sinking required for continuous operation.