LED Driver Ripple Current and Flicker Index Calculator
Calculate the ripple current percentage and flicker index of an LED driver from its peak, minimum, and average output current waveform values. These metrics are critical for evaluating LED flicker performance and driver quality.
Formulas Used
Ripple Current Percentage (per ANSI/IES TM-16 & IEEE PAR1789):
Ripple% = [ (I_peak − I_min) / (I_peak + I_min) ] × 100
Flicker Percent (IEEE PAR1789-2015 — identical to Ripple% for sinusoidal waveforms):
Flicker% = [ (I_peak − I_min) / (I_peak + I_min) ] × 100
Flicker Index (IES TM-16-2012 closed-form approximation):
Flicker Index = (I_peak − I_avg) / (2 × I_avg) Where I_avg is estimated as: • Sinusoidal / Triangular waveform: I_avg = (I_peak + I_min) / 2 • Square wave (full conduction): I_avg = I_peak → FI ≈ 0 • User-provided I_avg: used directly
Exact Flicker Index (from waveform area — requires full waveform data):
Flicker Index = (Area above average level) / (Total area under one cycle)
Assumptions & References
- Ripple current percentage and flicker percent use the same formula per IEEE PAR1789-2015 for sinusoidal-like waveforms.
- Flicker Index is computed using the IES TM-16-2012 closed-form approximation valid for smooth (sinusoidal or triangular) waveforms. For arbitrary waveforms, numerical integration over a full cycle is required.
- Average current is estimated as
(I_peak + I_min) / 2for sinusoidal and triangular waveforms. Provide a measured Iavg for higher accuracy. - Risk thresholds follow IEEE PAR1789-2015 guidelines: ≤8% flicker is generally considered low risk; 8–30% is moderate; >30% is high risk for occupied spaces.
- All current inputs are assumed to be in the same unit (mA); the unit cancels in all ratio-based formulas.
- This calculator assumes a steady-state periodic waveform. Transient or PWM-dimmed drivers may require time-domain analysis.
- References: IEEE PAR1789-2015, IES TM-16-2012, ENERGY STAR® Luminaires Specification v2.1 (flicker requirements).