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A complete high-power LED light requires four components that must be matched to each other: an LED module, a constant-current driver, a heatsink, and (optionally) an optic. This guide walks through selecting all four as a system, with two worked examples.
The Four Components
| Component | What It Does | Key Selection Criteria |
|---|---|---|
| LED Module | Produces the light | Color/CCT, lumens, form factor, Forward Voltage (Vf), drive current |
| Driver | Regulates constant current to the LED | Output current (must match LED), input voltage (must match power source), dimming |
| Heatsink | Removes heat to keep the LED within safe temperature | Thermal resistance (°C/W), physical size compatible with module |
| Optic | Shapes the beam (spot, flood, side-emit) | Beam angle, physical fit with module form factor |
Step 1: Choose the LED Module
Start here — the module determines requirements for everything else. See our Form Factor Guide and Color Temperature Guide for detailed guidance.
From the module you select, note these values for the remaining steps:
- Forward Voltage (Vf) — typically 2.9–3.5V per LED for white
- Drive current — typically 350mA or 700mA
- Number of LEDs — 1 (Stars/Squares), 3 (Tri-Stars), 4 (Quads), 7 (7-Ups)
- Power dissipation — Vf × current × number of LEDs (the heatsink must handle this)
Step 2: Choose the Driver
The driver’s output current must match the LED’s rated drive current exactly.
| Drive Current | Available Driver Families |
|---|---|
| 350mA | BuckPuck (DC/AC), BoostPuck, FlexBlock, MicroPuck, BuckToot |
| 500mA | BuckPuck (DC/AC), FlexBlock |
| 700mA | BuckPuck (DC/AC), PowerPuck, FlexBlock |
| 1000mA | BuckPuck (DC/AC), PowerPuck, BuckBlock |
| 1400–2100mA | BuckBlock |
Driver families
| Family | Input | Overhead Voltage | Use Case |
|---|---|---|---|
| BuckPuck DC | 5–32V DC | 2.5V | Most common. Batteries, DC supplies, solar. |
| BuckPuck AC | 120VAC | N/A | Plug into wall outlet. No separate supply needed. |
| PowerPuck | DC | 2.0V | Lower overhead than BuckPuck. Good for 12V automotive/marine. |
| BoostPuck | DC | N/A | Steps voltage up. For low-voltage sources (batteries). 350mA only. |
| BuckBlock | DC | Varies | High-power arrays up to 2100mA. |
| FlexBlock | DC | Varies | Compact. 350–700mA. |
| MicroPuck | DC | Varies | Smallest driver. 350mA only. |
Most drivers come in PCB Mount (bare board) or With Leads (pre-wired) versions. All 44 driver products at LED Drivers.
Minimum input voltage (DC buck drivers)
BuckPuck: Vin ≥ (Vf × LEDs) + 2.5V
PowerPuck: Vin ≥ (Vf × LEDs) + 2.0V
Example: Tri-Star with 3 white LEDs at Vf = 3.2V needs (3.2 × 3) + 2.5 = 12.1V minimum. A 12V supply is borderline — use 15V or 24V for headroom.
Dimming options
- Non-dimmable — Fixed output. Simplest.
- Externally dimmable — Potentiometer or 0–5V/PWM signal.
- Internally dimmable — Built-in pot. Set-and-forget.
Step 3: Choose the Heatsink
For a typical white LED, 60–75% of input power becomes heat. Heatsink performance is rated in °C/W — lower is better. Our 188 heatsinks range from 1.4 °C/W (100mm squares) to 26.2 °C/W (19mm squares).
Sizing formula
- P = Vf × I × number of LEDs (power dissipation in watts)
- R = temperature rise / P (required thermal resistance)
Use 40°C rise above ambient as the target for long LED life.
Example: Single white Rebel at 350mA: P = 3.2 × 0.35 = 1.12W. R = 40/1.12 = 35.7 °C/W. Even a 19mm heatsink (26.2 °C/W) is adequate.
Example: 7-Up Round at 350mA: P = 3.2 × 7 × 0.35 = 7.84W. R = 40/7.84 = 5.1 °C/W. Need a 50mm Square × 35mm (4.5 °C/W) or larger.
Module-to-heatsink compatibility
| Module | Minimum Heatsink |
|---|---|
| Z 5mm, 10mm Square, Rectangular | 19mm Square |
| Star, Tri-Star, Side Emitter, Quad | 25mm Square or 40mm Round |
| 25mm Round/Square, Star/O | 25mm Square |
| 7-Up Round (40mm) | 40mm Round or 45mm+ Square |
Mounting: Thermal tape (peel-and-stick, pre-cut per form factor) for low-power applications. Mechanical fastening with thermal compound for high-power. See Best Practices for Fastening LED Modules.
Step 4: Choose the Optic (Optional)
Without an optic, LEDs emit ~120° wide. An optic focuses this into a controlled beam. Skip this step if you want wide, unfocused illumination.
| Beam Angle | Use Case |
|---|---|
| 6°–10° | Tight spot, long-throw accent, display highlighting |
| 12°–20° | General spot, task lighting |
| 27°–50° | Medium to wide flood |
| 120°–180° | Downlight, ambient, hemispherical |
Elliptical optics (e.g., 9.5° × 40°) produce oval beams for wall washing. Frosted optics soften the hotspot.
Optic-to-module compatibility
| Module | Compatible Optics |
|---|---|
| Star, Tri-Star (20mm) | 20mm (Carclo, Khatod, Ledil) — widest selection |
| 10mm Square | 10mm (Carclo) |
| Rectangular | 15mm (Polymer Optics, Khatod) |
| 25mm Round, Star/O | 22–25mm (Fraen, Khatod) |
| 7-Up Round (40mm) | 39–50mm (Polymer Optics, Khatod), 7-cell cluster |
| 25mm Square, Side Emitter | Pre-installed — no separate optic needed |
| Z modules | No compatible optics |
All 76 optics products including holders and adhesive.
Worked Example 1: Compact Accent Light
Goal: Single focused spotlight for a display case. Warm white, narrow beam, 12V DC supply.
| Component | Choice | Key Numbers |
|---|---|---|
| Module | ANSI White (2700K) Rebel PLUS Star, 85 lm @ 350mA | Vf ~3.0V |
| Driver | 350mA Ext. Dimmable BuckPuck DC | Min Vin = 3.0 + 2.5 = 5.5V. 12V is fine. |
| Heatsink | 25mm Square × 20mm (13.7 °C/W) | P = 1.05W. Rise = 1.05 × 13.7 = 14°C. |
| Optic | Carclo 8° 20mm Circular Beam | Tight spot, fits 20mm Star |
| Mount | 20mm Hex thermal tape | Low power — tape is adequate |
Worked Example 2: High-Output Work Light
Goal: Maximum brightness for a garage workshop. Neutral white, wide beam, 24V DC supply.
| Component | Choice | Key Numbers |
|---|---|---|
| Module | Neutral White (4100K) Rebel ES 7-Up Round, 1610 lm @ 700mA | Vf ~3.2V × 7 = 22.4V |
| Driver | 700mA PowerPuck DC (not BuckPuck) | PowerPuck: min Vin = 22.4 + 2.0 = 24.4V. BuckPuck would need 24.9V — 24V supply is too low. Consider 28V supply or BuckPuck AC at 120VAC. |
| Heatsink | 70mm Square × 25mm (2.85 °C/W) | P = 15.7W. Rise = 15.7 × 2.85 = 45°C. A 60mm at 2.95 is marginal — 70mm gives safe margin. |
| Optic | Polymer Optics 50° 39mm | Wide flood, fits 40mm 7-Up |
| Mount | Mechanical (screws + thermal compound) | 15.7W — thermal tape not recommended at this power |
This example shows why calculations matter. A 24V supply is marginal for a 7-LED series string with a buck driver. Solutions: higher supply voltage, AC driver, or split into shorter series strings with separate drivers.
Common Mistakes
- No driver. LEDs are current-driven. Connecting directly to a voltage source will destroy them.
- No heatsink. The module’s MCPCB is a heat spreader, not a heatsink. Even a single 350mA LED needs external heatsinking.
- Insufficient supply voltage. The supply must cover the LED string voltage plus driver overhead. A 12V supply cannot drive four white LEDs in series (12.8V + 2.5V = 15.3V needed).
- Wrong heatsink metric. A large thin heatsink can have worse °C/W than a smaller tall one. Always check the rating.
- Wrong optic size. A 10mm optic won’t fit a 20mm Star. Check compatibility before ordering.
If you are unsure about compatibility, contact us or request a quote with your project description.
