LED Viewing Angle, mcd and Wavelength: Reading a Datasheet Correctly
Quick answer: five numbers decide whether an LED fits your design — forward voltage, rated current, luminous intensity (mcd), viewing angle, and dominant wavelength (or CCT for white). All five are on the first page of a datasheet, but they must be read together.
The Five Key Parameters
- Forward voltage (Vf): sets your resistor and driver headroom. Check min/max, not just typical.
- Forward current (If): rated test current (often 20 mA, or 2-5 mA for low-current types) and absolute maximum. mcd values apply only at the stated If.
- Luminous intensity (mcd): brightness on-axis. Only comparable between parts at the same current and beam angle.
- Viewing angle (2θ1/2): 15° is a spotlight, 120° is a flood. Angle trades against mcd at equal die brightness.
- Dominant wavelength / CCT: color. For white, check the chromaticity bin, not just the CCT number.
Binning Codes
Reels ship sorted into brightness and color bins printed on the label (e.g. rank K2, CCT bin 3A). Lock the bin in your purchase spec to keep panels uniform across production runs.
Also Check
Reflow profile and MSL level (assembly), reverse voltage limit (handling), and the pad/footprint drawing (layout). Our datasheet center covers all current models with these parameters on page one.
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