Constant-Current and Constant-Voltage LED Drivers
Read LED driver current, voltage windows and output modes, then compare the load requirements and dimming interface without assuming electrical interchangeability.
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Compare output modes
Constant-current (CC) and constant-voltage (CV) describe output regulation. They do not identify the dimming interface or guarantee that two drivers can operate the same luminaire. Compare the complete driver output specification against the LED load specification.
| Mode | Regulated quantity | Load information needed |
|---|---|---|
| Constant current | Current is regulated within a specified operating voltage window. | Required drive current and full forward-voltage range under the documented conditions. |
| Constant voltage | Voltage is regulated within the stated current/power range. | Rated supply voltage, current demand and load-side current regulation. |
| CC + CV operating regions | Some supplies move between voltage and current regulation. | The exact operating envelope; the mode cannot be inferred from maximum watts. |
| Dimming interface | A control input changes light output according to product design. | Supported interface, wiring, minimum output and compatibility with the control. |
Read the complete output label
Transcribe the exact model suffix, output current or adjustable range, voltage window, maximum output power and input ratings. Open-circuit voltage is not necessarily the normal LED operating voltage. Dimming leads are not the LED power output.
Illustrative comparison: a load specified for 700 mA across a 24–36 V forward-voltage range needs an output specification that covers that entire range at the required current. “30 W” alone cannot establish a match. A nominal 24 V CV strip instead needs its own voltage, current and power requirements checked.
Temperature-dependent voltage and driver derating must come from the two product documents. The numerical example is a reading exercise, not a product pairing.
Make a compatibility record
- Record driver and luminaire/LED module model numbers and approved replacement instructions.
- Compare regulation mode, current, voltage window and power limits.
- Check isolation, environmental ratings, temperature limits and mounting conditions.
- Check the dimming interface and control compatibility separately.
Use lighting control interfaces for the control side and LED tube types for complete retrofit arrangements. An output match alone does not approve a luminaire conversion.