IEEE 1789-2015
IEEE 1789-2015 — Recommended Practices for Modulating Current in High-Brightness LEDs for Mitigating Health Risks to Viewers
Definition
IEEE 1789-2015 is an IEEE recommended practice that defines low-risk and no-effect frequency / modulation-depth thresholds for current modulation in high-brightness LEDs. It is the most widely cited screening standard for LED flicker safety and the basis for FlickerSpec's pass/fail verdict on Quick measurements.
Source overview
IEEE 1789-2015 defines two regions on a frequency-vs-modulation-depth chart: a 'no-observable-effect' region (most conservative, safe under chronic exposure) and a 'low-risk' region (safe for most viewers in most settings). Modulation depth must fall below frequency-dependent limits to clear each region. The standard is recommended-practice not normative requirement, but it is the de-facto threshold cited in EU Ecodesign, US ENERGY STAR, and lighting-industry health discussions.
The underlying standard is paywalled or otherwise not directly reproducible here. The text above is a plain-language summary written by Slick Engineering — not a verbatim quote. Authoritative source linked below.
Technical detail
The 'low-risk' boundary is approximately percent flicker ≤ 0.0333 × frequency for 90 Hz < f ≤ 3 kHz. The 'no-effect' boundary is approximately half that — roughly percent flicker ≤ 0.01 × frequency over the same band. Below 90 Hz the curves are stricter because human visual flicker perception peaks around 8–10 Hz.
IEEE 1789-2015 was prepared by the IEEE Power Electronics Society and is positioned as a screening-grade standard rather than a perceptual measurement. It does not produce a single severity number like PstLM does; it produces a Pass / Low-Risk / Fail verdict against frequency-vs-modulation-depth curves.
FlickerSpec's Quick Measurement reports the IEEE 1789 verdict alongside percent flicker, flicker index, and dominant frequency. The IEC PstLM measurement (Pro tier) complements rather than replaces 1789 — they're aimed at different parts of the spectrum.
Where it appears
- FlickerSpec Used here
FlickerSpec Quick Measurement evaluates each capture against the IEEE 1789-2015 low-risk and no-effect thresholds and shows a Pass / Low-Risk / Fail verdict in the live readout and in the Pro PDF report.
Related terms
- PstLM
PstLM is a single-scalar perceptual metric for how annoying flicker from a light source is to a static human observer. PstLM = 1.0 correspon…
- Percent flicker
Percent flicker is the relative variation in light output of a source over one full modulation cycle, expressed as a percentage. 0% means no…
- Flicker index
Flicker index is a unitless number from 0 to 1 that captures both the amplitude and the waveform shape of light modulation. It is the area o…
- IEC TR 61547-1:2015
IEC TR 61547-1:2015 is the international Technical Report that defines a standardized light flickermeter — a model of human perceptual respo…