QED123 Infrared (IR) LED Emitter 880nm 5mm – Narrow Beam, High Power – onsemi

🧭 Product Description

The QED123 is a high-output infrared LED emitter manufactured by onsemi (formerly ON Semiconductor). Built with AlGaAs (Aluminum Gallium Arsenide) chip technology and encapsulated in a clear peach-tinted T-1 3/4 (5mm) package, it emits powerful infrared light at a peak wavelength of 880nm — invisible to the human eye but easily detected by silicon phototransistors and photodiodes.

With a narrow 16° emission angle and 70 mW/sr typical radiant intensity at 100 mA, the QED123 delivers a tightly focused, high-power IR beam ideal for long-range detection, optical communication, and precision sensing applications.

The QED123 is specifically designed to pair with the QSD123 and QSD124 phototransistors (sold separately), forming a matched emitter/detector pair optimized for maximum coupling efficiency at 880nm.

✅ Key Features

• Peak Emission Wavelength: 880nm (near-infrared, invisible to the human eye)
• High Radiant Intensity: 70 mW/sr typical at 100 mA — strong, focused IR output
• Narrow Emission Angle: 16° for precise, directional beam control
• Fast Switching: 900 ns rise time, 800 ns fall time — suitable for modulated/pulsed IR applications
• AlGaAs Chip Technology: Superior efficiency and output power compared to standard GaAs IR LEDs
• Wide Operating Range: -40°C to +100°C
• Standard T-1 3/4 (5mm) Package: Easy breadboard and through-hole PCB mounting
• Matched Detectors: Designed to pair with QSD123/QSD124 phototransistors
• Continuous Forward Current: Up to 100 mA
• Pb-Free / RoHS Compliant
• Manufacturer: onsemi (formerly ON Semiconductor)

📊 Specifications

Test conditions: IF = 100 mA, tp = 20 ms, TA = 25°C unless otherwise noted.

Power dissipation derated linearly at 2.67 mW/°C above 25°C.

🔌 Pin Identification

The QED123 is a 2-lead device in a standard T-1 3/4 (5mm) radial package:

Note: Like all LEDs, the QED123 is a polarized component. The flat edge on the base of the package identifies the cathode (−) lead. Reversing polarity will prevent the LED from emitting and may cause damage if reverse voltage exceeds 5V.

🔧 Typical Circuit Connection

Basic IR Emitter Circuit

Connect the QED123 in series with a current-limiting resistor to your DC supply:

VCC ──── R (current limiting) ──── QED123 Anode (+) ──── QED123 Cathode (−) ──── GND

Choosing a Current-Limiting Resistor

Use Ohm's Law: R = (VCC − VF) / IF

Note: VF is approximately 1.7V at 100 mA. For maximum IR output and detection range, drive at 100 mA. For battery-powered or low-power applications, 20 mA provides adequate output at shorter ranges.

Driving from a Microcontroller (Arduino, ESP32, etc.)

Most microcontroller GPIO pins can only source 20–40 mA. To drive the QED123 at full 100 mA output, use an NPN transistor or N-channel MOSFET as a switch:

When the GPIO pin goes HIGH, the transistor turns on and drives the QED123 at full current.

🔄 Matched Emitter/Detector Pair

The QED123 is specifically designed to work with onsemi's QSD12X phototransistor family:

Why use a matched pair?

• The QED123 emits at 880nm — the exact peak sensitivity wavelength of the QSD123/QSD124
• Matched spectral characteristics maximize coupling efficiency and detection range
• The QSD123/QSD124's built-in daylight filter blocks visible light while passing the QED123's 880nm emission, reducing false triggers

The QSD124 phototransistor is available in our store. Using the QED123 + QSD124 pair gives you the longest detection range and highest sensitivity combination in the QSD12X/QED12X family.

🛠️ Common Applications

• Object / Presence Detection — Transmit an IR beam to a QSD124 detector; detect when objects break the beam
• Optical Counters — Count items on a conveyor or production line
• Proximity Sensors — Detect nearby objects via reflected IR
• Optical Encoders — Rotary and linear position sensing
• Optical Switches / Interrupters — Slotted optical switch applications
• IR Remote Control Transmitters — Send IR commands to receivers
• Line-Following Robots — Illuminate surfaces for IR reflectance sensing
• Wireless IR Communication — Short-range data transmission via modulated IR
• Tachometers / RPM Counters — Provide the IR source for reflected/interrupted beam sensing
• Security Systems — IR beam break detection for perimeter monitoring

💡 Design Tips

• Pulsed operation allows higher peak currents and extends detection range without exceeding average power limits. The QED123's fast 900 ns rise time makes it well-suited for pulsed/modulated applications.
• Modulated IR (e.g., 38 kHz carrier) improves noise immunity in environments with ambient IR interference (sunlight, incandescent lighting).
• Alignment matters. With a narrow 16° emission angle, precise alignment between the QED123 emitter and QSD123/QSD124 detector is important for reliable detection, especially at longer distances.
• Temperature affects output. Radiant intensity decreases by approximately 0.3%/°C. At 85°C, output is roughly 82% of the 25°C value. Account for this in designs operating in high-temperature environments.
• Forward voltage decreases with temperature at -6 mV/°C. In temperature-variable environments, consider a constant-current driver rather than a simple resistor to maintain consistent output.

⚠️ Important Notes

1. Polarity matters. The QED123 is a diode — it only conducts in one direction. Reversing polarity will prevent emission. Do not exceed 5V reverse voltage.
2. Always use a current-limiting resistor. Connecting the QED123 directly to a voltage source without a resistor will destroy it.
3. Do not exceed 100 mA continuous forward current or 200 mW power dissipation (derate at 2.67 mW/°C above 25°C).
4. IR light is invisible. You cannot see the QED123's output with the naked eye. Use a smartphone camera (most can detect near-IR) to verify the LED is emitting, or use a phototransistor/photodiode circuit.
5. Soldering: Use RMA flux. Keep soldering iron tip at least 1.6mm (1/16") from the housing. Iron soldering: 240°C max for 5 seconds. Flow soldering: 260°C max for 10 seconds.
6. Not for life-support or medical implant applications per onsemi guidelines.

📦 What's in the Box

• 1, 2, 5, OR 10x QED123 Infrared LED Emitters (onsemi) - quantity selected above

Matched detector: The QSD124 IR phototransistor is the recommended paired detector for this emitter. [Check our store for availability.]

📘 Resources

• Datasheet: QED123/D (Rev. 2, August 2023)
• Matched Detectors: QSD123, QSD124