When selecting an LED power supply, check what it regulates as well as its wattage. Constant-current and constant-voltage supplies suit different lighting circuit arrangements.
What is the difference?
| Item | Constant-current drive (CC) | Constant-voltage drive (CV) |
|---|---|---|
| Regulated quantity | Current flowing through the LEDs | Voltage at the output terminals |
| Supply behavior | Adjusts voltage to maintain the selected current within its operating range | Maintains the selected voltage within its load range |
| Suitable lighting | LED circuits designed for a specified drive current | Lighting designed for a specified voltage with suitable current-limiting circuitry or a driver |
| Main matching requirements | Specified current, required voltage and output capacity | Specified voltage, required current and output capacity |
Do not assume bare LED components can be connected directly to a constant-voltage supply. Confirm the current-control or limiting arrangement and the specifications of both lighting and supply.
Why use constant current in image inspection?
LED brightness depends on current. Maintaining a selected current provides one basis for consistent illumination. Managing channel settings also helps reproduce conditions when independently adjusting several directions.
Constant-current drive does not automatically compensate for all changes in light output caused by temperature or aging. Manage the thermal state after switching on, camera exposure and gain as well.
Drive mode and dimming are separate concepts
Constant current and constant voltage describe output regulation. Analog and PWM dimming describe how brightness is changed. Manual and remote describe where commands originate. Keep these distinctions clear when defining the equipment configuration.
Front-panel controls and PC commands do not, by themselves, establish the internal dimming method or response time. To coordinate lighting with a camera, confirm terminal specifications and timing separately.
Checks when considering a four-channel controller
Our controller for hybrid lighting uses constant-current drive. It supports manual adjustment for each channel and external operation through serial communication.
- Do the lighting’s specified current and required voltage match?
- Are per-channel and total output conditions satisfied?
- Will you use front-panel adjustment or PC control?
- Is timing adjustment through external terminals needed?
A specification stating “24 V output” does not by itself mean 24 V constant-voltage drive. Confirm the drive mode and compatible load conditions together.
Reference: MEAN WELL — LED power supply technical Q&A. General drive principles are referenced here; OptTech product ratings and operation follow the supplied product specification.
