EM-323 is a one-quadrant PWM power controller designed for brushed DC motors and resistive loads. Its high-efficiency power stage provides adjustable output in one direction.
The PWM frequency can be selected between 2 kHz and 16 kHz. The higher frequency is intended for inductive loads such as DC motors, while the lower frequency can be used with resistive loads such as lamps.
The output is compensated against supply-voltage variations. Adjustable RxI load compensation also helps reduce motor-speed variation caused by changes in mechanical load, particularly at low speeds.
The EM-323 controls power in one direction. It is intended for applications that require adjustable forward motor operation or proportional control of a resistive load without electronic reversing.
Motor direction can be changed only by an external reversing circuit if bidirectional operation is required.
Two PWM frequencies are available. The 16 kHz setting is intended for inductive motor loads and provides quiet operation above the normal audible range.
The 2 kHz setting is intended for resistive loads such as lamps. The correct frequency mode should be selected according to the connected load.
The output is controlled using a 0–5 V or 0–10 V analog command signal. The control range can be adjusted to match the available command source.
The maximum output-voltage range can be configured between 5 V and 33 V, allowing the controller output to be matched to the connected motor or load.
The controller compensates the output against variations in the supply voltage. This helps maintain the selected output-voltage level when an unregulated power supply or battery voltage changes.
Adjustable RxI compensation increases the motor voltage as motor current rises. This compensates for part of the voltage drop caused by motor winding resistance and helps reduce motor-speed loss when mechanical load increases.
The function is especially useful at low motor speeds, where winding-resistance losses represent a larger proportion of the available motor voltage.
Separate start and stop ramps provide smooth output changes. Both ramp times can be adjusted between immediate response and 2.5 seconds.
The start ramp reduces sudden current and mechanical shock when the motor starts. The stop ramp lowers the output gradually when the command is removed or reduced.
The adjustable current limit protects the controller, motor and mechanical system against excessive current and torque.
The current limit can be set between 0.1 A and 8 A. The controller reduces its output when the selected current limit is reached.
The NPN fault output can supply a maximum current of 50 mA. It can be connected to an external controller, indicator or other compatible monitoring circuit.
An on-board 2.2 kΩ pull-up resistor can be connected using switch SW1 when the application requires a defined high level without an external pull-up resistor.
Parameters are configured using the EM-236 Interface Unit, connected to the red on-board connector.
The EM-236 displays the detected device type and firmware version. Select LOAD & EDIT to open the parameter-editing mode, choose the required parameter using the arrow buttons and change its value using the plus and minus buttons.
When parameter editing is complete, the new settings are stored by pressing and holding the save button.
The compact controller can be installed as a bare module or fitted into an optional DIN-rail mounting base for control-cabinet installations.
The EM-323 is suitable for fans, pumps, conveyors, feeders, lamps, heaters and other one-direction DC loads requiring adjustable output, soft starting and current limiting.
| PCB version | v2 |
| Supply voltage | 10–35 VDC |
| Overvoltage shutdown | 38 V |
| Maximum continuous output current | 4 A |
| Peak output current | 8 A for max. 10 s |
| Voltage loss | 0.3 V at 4 A |
| PWM frequency | 2 kHz or 16 kHz |
| Adjustable start ramp | 0–2.5 s |
| Adjustable stop ramp | 0–2.5 s |
| Adjustable current limit | 0.1–8 A |
| Analog control range | 0–5 V or 0–10 V, adjustable |
| Adjustable output-voltage range | 0–5 V…0–33 V |
| Analog control-input impedance | 100 kΩ |
| Fault output | NPN, max. 50 mA |
| Optional fault-output pull-up | 2.2 kΩ, enabled with SW1 |
| Supply and power connectors | Max. 1.5 mm² cable |
| Control connectors | Max. 1 mm² cable |
| Module dimensions | 72 × 20 × 17 mm |
| Dimensions with DIN-rail base | 90 × 23 × 48 mm |
| EMC | EN 50081-2 and EN 50082-2, industrial environment |
| Weight | 30 g |
| Operating temperature (Ta) | −40…+70 °C |
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