Constant Voltage vs Constant Current LED Drivers
Constant voltage drivers hold 12 V or 24 V fixed for strips and light boxes; constant current drivers hold the amps fixed for bare modules. How to choose.
Towe Engineering · Published November 2, 2026 · 3 min read
A constant voltage driver holds its output voltage fixed — 12 V or 24 V — and lets the load draw what it needs; it is the correct choice for LED strips, light boxes and any product with onboard current-limiting resistors. A constant current driver holds the output current fixed, for example 700 mA, and lets the voltage float; it is the correct choice for bare LED modules and COB engines without their own current limiting. Matching the mode to the load is the first specification decision in any lighting project.
Key points
- Strips and light boxes → constant voltage (12 V / 24 V)
- Bare LED modules and COB → constant current
- Wrong mode = flicker, overheating or dead LEDs on day one
- Dual-control drivers (CV + CC in one unit) serve mixed fleets
The one-sentence version
Constant voltage fixes the volts; constant current fixes the amps. Which one you need is decided by the LED product, not by preference.
Constant voltage: strips, boxes, coves
LED strips have resistors or regulator chips on the strip itself, so they only ask the driver for a stable 12 V or 24 V rail. Everything in the decorative and architectural strip world works this way:
- LED strips and cove lighting
- Fabric and acrylic light boxes
- Channel letters and luminous characters
- LED stair and linear lighting
Sizing is arithmetic: total load wattage plus 20% headroom. The Towe constant voltage range covers 60–600 W indoors (TF, TN, CB series) and 7–2000 W in IP67 outdoor formats (TH, TD, TY series).
Constant current: bare modules
A bare LED module or COB engine has no current limiting of its own — its current would run away with temperature until the chip dies. The driver must fix the current and let the voltage settle wherever the load puts it. Floodlight engines, downlight modules and COB boards live in this world.
The comparison table
| Constant voltage | Constant current | |
|---|---|---|
| Output held | Voltage (12/24 V) | Current (mA/A) |
| Load examples | Strips, boxes, signage | Modules, COB, engines |
| Sizing rule | Load W + 20% | Match the module’s mA rating |
| Typical failure if mismatched | Over-current burns the strip | Driver hunts, flickers or shuts down |
| Towe families | TF, TN, CB, TB, TZ, TT, TH, TD, TY | TD (dual control) |
When you need both
Contractors maintaining mixed fleets — strips in the ceiling, modules on the facade — end up stocking two kinds of driver. The Towe TD series puts constant voltage and constant current dual control in one IP67 housing precisely to halve that inventory, with models from 24 W to 2000 W.
If you are not sure which mode your load wants, send the LED product datasheet to sales before ordering. It is a two-minute check that prevents a very expensive installation-day surprise.
This article describes general manufacturing practice for machined and fabricated components. It is not a substitute for a drawing-specific engineering review — tolerances, material selection and process capability depend on the individual part.