3mm Infrared LED 850nm HIR204C Datasheet - T-1 Package - 1.45V Forward Voltage - 150mW Power - English Technical Document

1. Product Overview

This document details the specifications for a high-intensity 3mm (T-1) infrared light-emitting diode (LED). The device is designed to emit light at a peak wavelength of 850 nanometers (nm), making it suitable for a variety of infrared sensing and transmission applications. Its primary advantages include high reliability, significant radiant output, and a low forward voltage requirement.

The LED is constructed using Gallium Aluminum Arsenide (GaAlAs) chip material and is housed in a water-clear plastic package. This spectral output is intentionally matched to be compatible with common infrared receivers such as phototransistors, photodiodes, and integrated receiver modules. The product is compliant with RoHS (Restriction of Hazardous Substances) directives.

1.1 Target Applications

The device is engineered for systems requiring robust infrared signaling. Key application areas include:

• Free-air optical data transmission systems.
• Infrared remote control units, particularly those demanding higher output power.
• Smoke detection and fire alarm systems utilizing optical sensing principles.
• General-purpose infrared-based application systems for industrial or consumer use.

2. Technical Parameter Analysis

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation under these conditions is not guaranteed.

• Continuous Forward Current (I_F): 100 mA
• Peak Forward Current (I_FP): 1.0 A (Pulse Width ≤ 100μs, Duty Cycle ≤ 1%)
• Reverse Voltage (V_R): 5 V
• Operating Temperature (T_opr): -40°C to +85°C
• Storage Temperature (T_stg): -40°C to +100°C
• Soldering Temperature (T_sol): 260°C (for ≤ 5 seconds)
• Power Dissipation (P_d): 150 mW (at or below 25°C ambient temperature)

2.2 Electro-Optical Characteristics (T_a = 25°C)

These parameters define the typical performance of the device under specified test conditions.

• Radiant Intensity (I_e):
  • Typical: 17.6 mW/sr at I_F = 20 mA.
  • Typical: 90 mW/sr at I_F = 100 mA (pulsed).
  • Typical: 900 mW/sr at I_F = 1 A (pulsed).
• Peak Wavelength (λ_p): Typical 850 nm at I_F = 20 mA.
• Spectral Bandwidth (Δλ): Typical 45 nm at I_F = 20 mA.
• Forward Voltage (V_F):
  • Typical: 1.45 V, Maximum: 1.65 V at I_F = 20 mA.
  • Typical: 1.80 V, Maximum: 2.40 V at I_F = 100 mA (pulsed).
  • Typical: 4.10 V, Maximum: 5.25 V at I_F = 1 A (pulsed).
• Reverse Current (I_R): Maximum 10 μA at V_R = 5 V.
• View Angle (2θ_1/2): Typical 25 degrees at I_F = 20 mA.

Note: Measurement uncertainties are specified for forward voltage (±0.1V), radiant intensity (±10%), and dominant wavelength (±1.0nm).

3. Performance Curve Analysis

The datasheet provides several characteristic curves that illustrate device behavior under varying conditions. These are critical for design engineers to predict performance in real-world applications.

3.1 Forward Current vs. Ambient Temperature

This curve shows the derating of the maximum allowable forward current as the ambient temperature increases. The device's power dissipation capability decreases with rising temperature, which must be accounted for in thermal design to prevent overheating.

3.2 Spectral Distribution

The spectral output graph confirms the peak emission at 850nm with a defined bandwidth. This is essential for ensuring compatibility with the spectral sensitivity of the intended receiver (e.g., a silicon photodetector, which is most sensitive around 800-900nm).

3.3 Radiant Intensity vs. Forward Current

This plot demonstrates the relationship between drive current and optical output. It typically shows a sub-linear increase, meaning efficiency may drop at very high currents. Designers use this to select an operating point that balances output power with efficiency and device longevity.

3.4 Relative Radiant Intensity vs. Angular Displacement

This polar plot defines the spatial emission pattern (viewing angle). The typical 25-degree half-angle indicates a moderately focused beam, which is useful for directing infrared energy towards a specific target or sensor.

3.5 Peak Emission Wavelength vs. Ambient Temperature

Infrared LEDs exhibit a shift in peak wavelength with temperature, typically around 0.2-0.3 nm/°C. This curve quantifies that shift for the HIR204C, which is important for applications where precise wavelength matching is critical.

3.6 Forward Current vs. Forward Voltage (I-V Curve)

The fundamental electrical characteristic of a diode. This curve is used to determine the voltage drop across the LED at a given operating current, which is necessary for designing the driving circuitry (e.g., selecting a current-limiting resistor or designing a constant-current driver).

4. Mechanical and Package Information

4.1 Package Dimensions (T-1, 3mm)

The device conforms to the standard T-1 (3mm) radial leaded package dimensions. Key mechanical specifications include:

• Overall package diameter is approximately 3.0mm.
• Standard lead spacing (between centers) is 2.54mm (0.1 inches).
• A detailed dimensioned drawing is provided in the datasheet, specifying lengths, diameters, and lead wire gauges with a general tolerance of ±0.25mm unless otherwise noted.

4.2 Polarity Identification

The LED has a flat side on the lens or a shorter lead to indicate the cathode (negative) terminal. Correct polarity must be observed during circuit assembly.

5. Soldering and Assembly Guidelines

Proper handling is crucial to maintain device reliability and performance.

5.1 Lead Forming

• Bending must occur at least 3mm from the base of the epoxy lens to avoid stress on the internal die and wire bonds.
• Form leads before soldering.
• Avoid applying stress to the package. PCB holes must align perfectly with the LED leads to prevent mounting stress.
• Cut leads at room temperature.

5.2 Storage Conditions

• Recommended storage: ≤ 30°C and ≤ 70% Relative Humidity (RH).
• Shelf life after shipment is 3 months under these conditions.
• For longer storage (up to 1 year), use a sealed container with a nitrogen atmosphere and desiccant.
• Avoid rapid temperature changes in humid environments to prevent condensation.

5.3 Soldering Recommendations

Maintain a minimum distance of 3mm from the solder joint to the epoxy bulb.

• Hand Soldering: Iron tip temperature ≤ 300°C (max 30W), soldering time ≤ 3 seconds.
• Wave/Dip Soldering: Preheat ≤ 100°C (max 60 sec), solder bath ≤ 260°C, dwell time ≤ 5 seconds.
• Avoid stress on leads during high-temperature operations.
• Do not perform dip/hand soldering more than once.
• Allow the device to cool gradually to room temperature after soldering, protecting it from shock or vibration during cooling.

5.4 Cleaning

• If necessary, clean only with isopropyl alcohol at room temperature for ≤ 1 minute. Air dry.
• Ultrasonic cleaning is not recommended. If unavoidable, its potential impact must be carefully evaluated.

6. Packaging and Ordering Information

6.1 Packing Materials & Specification

The devices are packed using moisture-resistant materials to prevent damage during storage and transport. The packing hierarchy is:

1. Devices are placed in anti-static bags.
2. Bags are placed in inner cartons.
3. Inner cartons are packed into master shipping cartons.

6.2 Packing Quantities

• Minimum 200 to 1000 pieces per anti-static bag.
• 5 bags per inner box.
• 10 boxes per master shipping carton.

6.3 Label Explanation

Labels on packaging contain key identifiers:

• CPN: Customer's Production Number
• P/N: Production Number (Part Number)
• QTY: Packing Quantity
• CAT: Ranks (performance bins)
• HUE: Dominant Wavelength
• REF: Reference
• LOT No: Lot Number for traceability

7. Application Design Considerations

7.1 Driving Circuit Design

Due to the diode's exponential I-V characteristic, a constant-current driver or a current-limiting resistor is mandatory. The resistor value (R_limit) can be calculated using Ohm's Law: R_limit = (V_supply - V_F) / I_F. Always use the maximum V_F from the datasheet for a given I_F to ensure sufficient current under all conditions. For pulsed operation (e.g., remote controls), ensure the driver can supply the high peak current (up to 1A) with the correct duty cycle.

7.2 Thermal Management

While the package can dissipate 150mW at 25°C, this rating derates with ambient temperature. In enclosed spaces or high ambient temperatures, ensure the actual power dissipation (I_F * V_F) remains below the derated limit. Adequate PCB copper area or other heatsinking may be required for continuous high-current operation.

7.3 Optical Design

The 25-degree viewing angle provides a balance between beam concentration and coverage. For longer-range applications, secondary optics (lenses) may be used to collimate the beam. For wide-area coverage, a diffuser might be necessary. Ensure the receiver's field of view and spectral sensitivity align with the LED's output.

8. Technical Comparison and Differentiation

The HIR204C's key differentiators in its class (3mm IR LEDs) are its combination of high radiant intensity (up to 900 mW/sr pulsed) and relatively low forward voltage (typical 1.45V at 20mA). This makes it efficient, reducing power consumption and heat generation for a given light output compared to devices with higher V_F. The 850nm wavelength is a standard for silicon-based receivers, offering a good balance between receiver sensitivity and relative invisibility. Its robust construction and clear package material contribute to its stated high reliability.

9. Frequently Asked Questions (FAQs)

9.1 What is the difference between continuous and pulsed current ratings?

The continuous current rating (100mA) is the maximum DC current the LED can handle indefinitely without risk of damage. The pulsed current rating (1A) is much higher but can only be applied for very short pulses (≤100μs) at a very low duty cycle (≤1%). This allows for brief bursts of very high brightness, common in remote control signals, without overheating the device.

9.2 Why is the forward voltage higher at 1A compared to 20mA?

This is due to the inherent series resistance within the LED chip and package. As current increases, the voltage drop across this internal resistance (V = I * R) increases, leading to a higher total forward voltage. The datasheet provides this data so drivers can be designed to supply the necessary voltage at the target operating current.

9.3 Can this LED be used for data transmission?

Yes, its fast switching capability (implied by its use in remote controls) makes it suitable for modulated data transmission in free-air systems. The achievable data rate will depend on the driver circuit's ability to switch the current rapidly and the receiver's bandwidth.

10. Practical Use Case Example

10.1 Designing a Simple IR Beacon

Objective: Create a continuously-on IR beacon for proximity sensing with a range of a few meters.

Design Steps:

1. Choose Operating Point: Select I_F = 50mA for a balance of good output and moderate power. From the I-V curve, estimate V_F ≈ 1.6V.
2. Calculate Driver: Using a 5V supply and a series resistor: R = (5V - 1.6V) / 0.05A = 68Ω. Power in resistor: P = I²R = (0.05)² * 68 = 0.17W. Use a 68Ω, 0.25W resistor.
3. Thermal Check: LED power dissipation: P_LED = V_F * I_F = 1.6V * 0.05A = 80mW. This is well below the 150mW rating at 25°C. If ambient temperature is expected to be 50°C, consult the derating curve to ensure 80mW is still safe.
4. Mounting: Place on PCB with holes aligned to leads. Solder, keeping joints >3mm from lens body.
5. Pairing: Use a phototransistor or receiver module sensitive to 850nm light, placed within the 25-degree beam cone of the LED.

11. Operating Principle

An infrared LED is a semiconductor p-n junction diode. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the junction region. When these charge carriers recombine, they release energy in the form of photons (light). The specific semiconductor material used (GaAlAs in this case) determines the bandgap energy, which directly defines the wavelength of the emitted photons—in this instance, in the near-infrared region around 850nm. The water-clear epoxy package acts as a lens, shaping the output beam, and protects the delicate semiconductor chip.

12. Technology Trends

The development of infrared LEDs continues to focus on several key areas: Increased Efficiency (more optical power output per electrical watt input), Higher Power Density (smaller packages capable of handling more current), and Improved Reliability under harsh environmental conditions. There is also ongoing work to develop devices at other specific wavelengths (e.g., 940nm for improved covertness, or specific wavelengths for gas sensing). Integration with driver circuitry and receivers into compact modules is another significant trend, simplifying system design for end-users. The HIR204C represents a mature, reliable technology well-suited for its intended applications.