2. Article Body
📌 Product Overview
The XL-SFH7015 is a specialized side-viewing SMD LED component designed to emit both Red (660nm) and Infrared (870nm) light, making it ideal for optical biosensing applications. 💡 Encapsulated in a compact 2.0 x 0.8 x 0.4mm package, this component supports the high-density integration requirements of modern wearable PCBs. Its primary design focus is to provide stable light output for Blood Oxygen (SpO2) and Heart Rate monitoring (PPG) modules. By offering two wavelengths in a single miniature footprint, it simplifies optical alignment and conserves board space in body-worn devices.
⚙️ Typical Applications
Based on its optical peak wavelengths and power output, the XL-SFH7015 is optimized for the following specific use cases:
- Pulse Oximetry & SpO2 Monitoring: Utilizing the specific absorption characteristics of 660nm (Red) and 870nm (IR) light to calculate oxygen saturation.
- Heart Rate Detection (PPG): Enabling photoplethysmography to measure heart rate variability in smartwatches and fitness bands.
- Compact Wearables: Suitable for integration into smart watches, wristbands, and health patches where physical height is limited.
- Medical Electronic Devices: Used in professional-grade patient monitoring systems requiring high-reliability optical components.
📊 Key Technical Specifications
The following electrical and optical characteristics are measured under standard test conditions (Ta=25°C).
| Parameter | Symbol | Red (Min / Typ / Max) | IR (Min / Typ / Max) | Unit | Condition |
|---|---|---|---|---|---|
| Forward Voltage | VF | - / - / 2.5 | - / - / 1.7 | V | IF = 20mA |
| Peak Wavelength | λp | 655 / 660 / 665 | 850 / 870 / 890 | nm | IF = 20mA |
| Optical Power | PO | 8.5 / 10.5 / - | 6.0 / 7.2 / - | mW | IF = 20mA |
| Half Viewing Angle | θ1/2 | - | ±60 | deg | - |
| Reverse Current | IR | - | - | 10 | μA |
💡 Note: Pulsed operation (200mA, 1/10 Duty) delivers significantly higher output power (Red: 75mW, IR: 50mW) for improved signal-to-noise ratio in noisy environments.
⚡ Absolute Maximum Ratings & Process Limits
Exceeding these values may result in permanent damage to the component. Design margins must account for these limits to ensure field reliability.
| Parameter | Symbol | Rating | Unit | Notes |
|---|---|---|---|---|
| DC Forward Current | IF(R)/IF(IR) | 50 | mA | Continuous operation limit |
| Pulse Forward Current | IFP(R)/IFP(IR) | 200 | mA | Pulse width 0.5ms, Duty 1/10 |
| Max Reverse Voltage | VR | 5 | V | |
| Operating Temp. | TOPR | -40 to +85 | °C | Ambient temperature range |
| Storage Temp. | TSTR | -40 to +100 | °C | |
| Soldering Temp. | TSOL | 260 | °C | ≤ 6 seconds (Manual/Reflow) |
🔒 Critical Risk Control: ESD-HBM protection is tested up to 2000V. Handling precautions are mandatory during assembly to prevent latent failures.
🏗️ Package, Dimensions & Assembly Notes
- Package Type: Side-viewing SMD, ideal for space-constrained optical windows.
- Dimensions: 2.0mm (L) x 0.8mm (W) x 0.4mm (H).
- Packaging: EIA Standard Tape and Reel (implied for SMT).
- Soldering Compatibility:
- Suitable for standard Reflow Soldering processes.
- Moisture Sensitivity Level (MSL): 3. Components must be baked according to J-STD-033 if the floor life is exceeded before reflow.
- ⚠️ Preconditioning: Reliability testing includes 8 hours at 155°C prior to soldering to simulate board stresses.
📦 Sourcing & Supply Considerations
- Authenticity Verification: Ensure markings and packaging dimensions match the datasheet to avoid counterfeit components.
- MSL Management: Verify dry-pack status upon receipt; MSL 3 requires strict moisture control.
- Sample Evaluation: Request binning data for Wavelength and Forward Voltage to optimize driver circuit design.
- Yield Rate: High uniformity in viewing angle (±60°) reduces calibration complexity in production.
❓ FAQ
Q: What is the typical Forward Voltage for the Infrared LED?
A: The typical Forward Voltage (VF) for the IR emitter is 1.7V at a test current of 20mA. Designers should ensure the driver circuit can supply sufficient voltage while respecting the 50mA DC current limit.
Q: Can this LED be used for reflow soldering?
A: Yes, the XL-SFH7015 is designed for SMT production and is suitable for standard reflow soldering processes. It has a maximum soldering temperature rating of 260°C for ≤6 seconds.
Q: What are the storage requirements to prevent damage?
A: Since the component has a Moisture Sensitivity Level (MSL) of 3, it should be stored in a dry environment. If the vacuum-sealed bag is opened and the components are exposed to ambient humidity for more than the specified floor life, they must be baked at 125°C prior to reflow to prevent "popcorning" or internal cracking.
Q: How does the optical power vary with pulse current?
A: The optical power increases significantly under pulsed conditions. At DC 20mA, the Red LED outputs 10.5mW. However, under pulsed conditions (200mA, 1/10 duty), it can reach up to 75mW, which is essential for penetrating tissue and obtaining a strong PPG signal.
Q: What is the viewing angle of this LED?
A: The Half Viewing Angle is ±60 degrees. This wide angle helps in collecting reflected light from the skin even if the sensor alignment is not perfectly perpendicular to the skin surface.
