IR95-21C/TR7 Infrared LED Datasheet - 1.9mm Round SMD - 1.2V - 940nm - 130mW - English Technical Document

1. Product Overview

The IR95-21C/TR7 is a subminiature surface-mount device (SMD) infrared emitting diode. It is housed in a compact, double-ended package with a spherical top-view lens molded from water-clear plastic. This device is specifically engineered for spectral matching with silicon photodiodes and phototransistors, making it an ideal source for various infrared sensing applications.

1.1 Core Advantages and Target Market

This component offers several key advantages including a very small form factor, high reliability, and low forward voltage operation. Its primary target markets include consumer electronics, industrial automation, and safety equipment where reliable infrared emission in a confined space is required.

2. In-Depth Technical Parameter Analysis

The performance of the IR95-21C/TR7 is defined by its electrical, optical, and thermal characteristics under specified conditions.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. They are not intended for continuous operation.

• Continuous Forward Current (I_F): 65 mA
• Reverse Voltage (V_R): 5 V
• Operating Temperature (T_opr): -25°C to +85°C
• Storage Temperature (T_stg): -40°C to +85°C
• Power Dissipation (P_d): 130 mW (at or below 25°C ambient)
• Soldering Temperature (T_sol): 260°C for ≤ 5 seconds

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

These parameters are measured at a standard test current of 20 mA and represent the device's typical performance.

• Radiant Intensity (I_e): 3.0 mW/sr (Min), 5.0 mW/sr (Typ)
• Peak Wavelength (λ_p): 940 nm (Typ)
• Spectral Bandwidth (Δλ): 45 nm (Typ)
• Forward Voltage (V_F): 1.2 V (Typ), 1.5 V (Max)
• Reverse Current (I_R): 10 μA (Max) at V_R=5V
• View Angle (2θ_1/2): 25° (Typ)

3. Performance Curve Analysis

The datasheet provides several characteristic curves that are crucial for design engineers.

3.1 Forward Current vs. Ambient Temperature

This curve shows the derating of the maximum allowable forward current as the ambient temperature increases above 25°C. Proper thermal management is essential to stay within the safe operating area.

3.2 Spectral Distribution

The spectral output curve centers around the typical peak wavelength of 940 nm with a bandwidth of approximately 45 nm. This matches well with the peak sensitivity of common silicon photodetectors.

3.3 Relative Radiant Intensity vs. Forward Current

This graph illustrates the non-linear relationship between drive current and optical output. The radiant intensity increases with current but designers must consider efficiency and heat generation.

3.4 Forward Current vs. Forward Voltage

The I-V curve demonstrates the diode's exponential characteristic. The typical forward voltage is 1.2V at 20mA, which is relatively low, aiding in low-power circuit design.

3.5 Relative Radiant Intensity vs. Angular Displacement

This polar plot defines the spatial emission pattern of the LED. The 25° viewing angle indicates a moderately directional beam, which is useful for targeted sensing applications.

4. Mechanical and Package Information

4.1 Package Dimensions

The IR95-21C/TR7 features a 1.9mm round body with "gull-wing" leads for surface mounting. Key dimensions include the body diameter, overall height, and lead spacing. All critical dimensions have a tolerance of ±0.1mm unless otherwise specified. The gull-wing lead design provides good mechanical stability during and after the soldering process.

4.2 Polarity Identification

The cathode is typically indicated by a visual marker such as a notch, flat edge, or shorter lead on the package. Consult the detailed package drawing for the specific identification method used on this component.

5. Soldering and Assembly Guidelines

Proper handling is critical for SMD components to ensure reliability.

5.1 Storage and Moisture Sensitivity

This device is moisture sensitive. It must be stored in its original moisture-proof bag at ≤ 30°C and ≤ 90% RH before opening. After opening, it should be stored at ≤ 30°C and ≤ 60% RH and used within 168 hours (7 days). If these conditions are exceeded, a baking treatment at 60 ± 5°C for 24 hours is required before use.

5.2 Reflow Soldering Profile

The datasheet specifies a lead-free soldering temperature profile. Reflow soldering should not be performed more than two times. During heating, no mechanical stress should be applied to the LED body, and the PCB should not be warped after soldering.

5.3 Hand Soldering and Rework

If hand soldering is necessary, a soldering iron with a tip temperature < 350°C and capacity ≤ 25W should be used. Contact time per lead should be ≤ 3 seconds. Rework is strongly discouraged. If unavoidable, a specialized double-head soldering iron must be used to simultaneously heat both leads, preventing thermal stress on the epoxy body.

6. Packaging and Ordering Information

6.1 Carrier Taping

The components are supplied on embossed carrier tape for automated assembly. The standard loaded quantity is 1000 pieces per reel. Detailed tape and reel dimensions are provided for feeder compatibility.

6.2 Label Specification

The reel label contains essential information including Part Number (P/N), Customer's Production Number (CPN), quantity (QTY), rank (CAT), peak wavelength (HUE), reference (REF), and lot number (LOT No.).

7. Application Suggestions

7.1 Typical Application Circuits

The primary application is as an infrared source paired with a silicon photodetector. A current-limiting resistor is absolutely mandatory in series with the LED. The resistor value (R) is calculated using the formula: R = (V_supply - V_F) / I_F. Since V_F is low (~1.2V), even small increases in supply voltage can cause large current surges, necessitating precise resistor calculation or the use of a constant current driver for critical applications.

7.2 Design Considerations

• Optical Alignment: The 25° viewing angle requires careful mechanical alignment with the receiving sensor for optimal signal strength.
• Thermal Management: While power dissipation is low, PCB layout should avoid placing heat-generating components nearby, especially if operating at high ambient temperatures or near the maximum current.
• Electrical Noise: In sensitive analog sensing circuits, consider shielding or filtering to prevent the pulsed LED drive current from introducing noise.

8. Technical Comparison and Differentiation

The IR95-21C/TR7 differentiates itself through its combination of a very compact 1.9mm round package, gull-wing leads for robust soldering, and a spectral output precisely matched to silicon detectors. Compared to larger through-hole IR LEDs, it saves significant board space. Compared to other SMD packages, the spherical lens and specific viewing angle may offer better optical coupling for certain barrier or proximity sensor designs.

9. Frequently Asked Questions (Based on Technical Parameters)

9.1 What happens if I exceed the 65mA forward current?

Exceeding the Absolute Maximum Rating for forward current can cause immediate catastrophic failure due to overheating of the semiconductor junction, or significantly reduce the device's long-term reliability and luminous output.

9.2 Can I use this for continuous operation?

Yes, but you must ensure the operating point (I_F, T_a) lies within the safe operating area defined by the maximum power dissipation curve. At 25°C, the maximum continuous power is 130mW. At higher ambient temperatures, the maximum allowable current must be derated.

9.3 Why is the storage and usage time after opening so critical?

The epoxy packaging material can absorb moisture from the air. During the high-temperature reflow soldering process, this trapped moisture can vaporize rapidly, causing internal delamination, cracking, or "popcorning," which destroys the component. The specified storage conditions and floor life control this risk.

10. Practical Design and Usage Case

Case: Designing a Compact Paper Presence Sensor in a Printer. The IR95-21C/TR7 is an excellent choice. Its small size allows it to fit into tight mechanical assemblies. The designer would pair it with a phototransistor placed a few millimeters away, creating a transmission-type sensor. A microcontroller would pulse the LED with a 20mA current (using a suitable series resistor) and read the phototransistor's output. The 940nm wavelength is invisible and won't interfere with user experience. The gull-wing leads provide a strong solder joint resistant to vibration within the printer mechanism. Strict adherence to the reflow profile and moisture handling procedures is essential for high manufacturing yield.

11. Operating Principle

An Infrared Light Emitting Diode (IR LED) is a semiconductor p-n junction diode. When forward biased, electrons from the n-region recombine with holes from the p-region in the active region. This recombination process releases energy in the form of photons. The specific material used (Gallium Aluminum Arsenide - GaAlAs in this case) determines the bandgap energy, which directly defines the wavelength of the emitted light, here in the infrared spectrum around 940nm.

12. Industry Trends

The trend in optoelectronics continues towards miniaturization, higher efficiency, and integration. SMD packages like this one have largely replaced through-hole components in automated assembly. Future developments may include even smaller chip-scale packages (CSP), integrated driver circuits within the package, and components designed for higher speed modulation for data communication applications. There is also a sustained focus on improving reliability and simplifying assembly processes, such as reducing moisture sensitivity levels.