LED Indicator Lamp A1844B/4SYG/S530-E2 Datasheet - Brilliant Yellow Green - 20mA - 60mW - English Technical Document

1. Product Overview

The A1844B/4SYG/S530-E2 is a low-power, high-efficiency LED indicator lamp designed for general-purpose indication applications in electronic equipment. It emits a brilliant yellow-green light, offering excellent visibility. The device is constructed as an array, combining a plastic holder with the LED lamp, which facilitates easy mounting on panels or printed circuit boards (PCBs). Its primary design goals are reliability, ease of assembly, and cost-effectiveness for mass production environments.

Key advantages of this product include its stackable design, allowing for both vertical and horizontal arrangement to create custom indicator clusters. It complies with major environmental regulations, including the EU's RoHS (Restriction of Hazardous Substances) and REACH directives, and is manufactured as a halogen-free component, with bromine and chlorine content kept below specified limits (Br <900 ppm, Cl <900 ppm, Br+Cl < 1500 ppm). This makes it suitable for use in products with stringent environmental requirements.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

The Absolute Maximum Ratings define the stress limits beyond which permanent damage to the device may occur. These ratings are not intended for continuous operation. For the A1844B/4SYG/S530-E2, the continuous forward current (I_F) is rated at 25 mA. A higher peak forward current (I_FP) of 60 mA is permissible but only under pulsed conditions with a duty cycle of 1/10 at 1 kHz. The maximum reverse voltage (V_R) is 5 V, emphasizing the need for correct polarity during installation. The power dissipation (P_d) limit is 60 mW, which is crucial for thermal management. The device operates within a temperature range of -40°C to +85°C and can be stored at temperatures up to +100°C. The soldering temperature rating is 260°C for a maximum of 5 seconds, which is a standard for lead-free soldering processes.

2.2 Electro-Optical Characteristics

The Electro-Optical Characteristics are measured under standard conditions (Ta=25°C) and define the device's typical performance. The forward voltage (V_F) ranges from 1.7V to 2.4V, with a typical value of 2.0V when driven at the standard test current of 20 mA. This parameter is critical for designing the current-limiting resistor in the driving circuit. The luminous intensity (I_V) has a minimum value of 16 mcd and a typical value of 32 mcd, indicating a bright output suitable for indicator purposes. The viewing angle (2θ_1/2) is typically 60 degrees, providing a wide beam of light. The peak wavelength (λ_p) is typically 575 nm, and the dominant wavelength (λ_d) is typically 573 nm, both characterizing the yellow-green color of the emitted light. The spectrum radiation bandwidth (Δλ) is typically 20 nm, describing the spectral purity of the light.

3. Performance Curve Analysis

The datasheet provides several characteristic curves that offer deeper insight into the LED's behavior under varying conditions.

3.1 Relative Intensity vs. Wavelength

This curve shows the spectral power distribution of the emitted light. For the SYG (Super Yellow Green) type, the curve will peak around the 573-575 nm region, confirming the dominant and peak wavelength specifications. The shape of this curve determines the perceived color.

3.2 Directivity Pattern

The directivity curve illustrates how the luminous intensity varies with the viewing angle relative to the LED's central axis. The typical 60-degree viewing angle (2θ_1/2) means the intensity drops to half its maximum value at ±30 degrees from the axis. This pattern is important for applications requiring specific illumination angles.

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

This fundamental curve shows the nonlinear relationship between the current flowing through the LED and the voltage across it. It demonstrates the diode's characteristic turn-on voltage and is essential for designing stable drive circuits, as small changes in voltage can lead to large changes in current.

3.4 Relative Intensity vs. Forward Current

This curve shows how the light output (relative intensity) increases with the forward current. It is generally linear over a range but will saturate at very high currents. Operating within the specified 20mA ensures optimal efficiency and longevity.

3.5 Temperature Dependence Curves

Two key curves show the effect of ambient temperature (T_a). The Relative Intensity vs. Ambient Temperature curve typically shows a decrease in light output as temperature increases. The Forward Current vs. Ambient Temperature curve, likely under constant voltage conditions, shows how the current changes with temperature. These curves are vital for designing applications that operate in non-standard temperature environments, as they highlight the need for thermal management and potential current derating.

4. Mechanical and Packaging Information

4.1 Package Dimensions

The datasheet includes a detailed dimensional drawing of the LED package. Key dimensions include the overall height, the diameter of the epoxy lens (bulb), and the lead spacing. The lead spacing is measured where the leads emerge from the package body. All dimensions are in millimeters, with a general tolerance of ±0.25 mm unless otherwise specified. This drawing is critical for PCB layout designers to ensure the correct footprint and hole placement are used.

4.2 Polarity Identification

Typically, the longer lead denotes the anode (positive) connection, and a flat spot on the lens or package body may also indicate the cathode side. Correct polarity must be observed during assembly to prevent reverse bias, which is limited to 5V.

5. Soldering and Assembly Guidelines

Proper handling is crucial for reliability. Specific guidelines are provided:

5.1 Lead Forming

Leads should be bent at a point at least 3mm away from the base of the epoxy bulb. Forming must be done before soldering and at room temperature to avoid stressing the package, which can damage the internal die or crack the epoxy. PCB holes must align perfectly with the LED leads to avoid mounting stress.

5.2 Storage

LEDs should be stored at 30°C or less and 70% relative humidity or less. The recommended storage life after shipment is 3 months. For longer storage (up to one year), they should be kept in a sealed container with a nitrogen atmosphere and desiccant.

5.3 Soldering Process

A minimum distance of 3mm must be maintained between the solder joint and the epoxy bulb. Recommended conditions are:
Hand Soldering: Iron tip temperature max 300°C (for 30W max iron), soldering time max 3 seconds.
Wave/DIP Soldering: Preheat temperature max 100°C (for max 60 sec), solder bath temperature max 260°C for max 5 seconds.
A soldering profile graph is recommended, showing a gradual preheat, a controlled time above liquidus, and a controlled cooldown. Rapid cooling should be avoided. Soldering (dip or hand) should not be performed more than once. After soldering, the LED should be protected from mechanical shock until it returns to room temperature.

5.4 Cleaning

If cleaning is necessary, use isopropyl alcohol at room temperature for no more than one minute, then air dry. Ultrasonic cleaning is generally not recommended due to the risk of damaging the package; if absolutely required, its parameters (power, time) must be carefully pre-qualified.

5.5 Heat Management

Although this is a low-power device, heat management must be considered in the application design. The operating current should be derated appropriately if the ambient temperature is high, referring to any de-rating curves. Proper heat sinking or airflow may be necessary in high-density or high-temperature applications to maintain performance and lifespan.

6. Packaging and Ordering Information

6.1 Packing Specification

The LEDs are packed using moisture-resistant materials. The standard packing flow is: 140 pieces per anti-static plate, 3 plates per inner carton, and 10 inner cartons per master (outside) carton. This totals 4,200 pieces per master carton.

6.2 Label Explanation

The packaging label contains several codes:
• CPN: Customer's Production Number.
• P/N: Production Number (the part number).
• QTY: Packing Quantity.
• CAT: Ranks of Luminous Intensity (binning for brightness).
• HUE: Ranks of Dominant Wavelength (binning for color).
• REF: Ranks of Forward Voltage (binning for V_F).
• LOT No: Manufacturing Lot Number for traceability.

7. Application Notes and Design Considerations

7.1 Typical Applications

This LED is designed as an indicator for displaying status, degree, function, or position in a wide range of electronic instruments and devices. Examples include power-on indicators, mode selectors, level indicators on audio equipment, and status lights on industrial control panels.

7.2 Circuit Design

A simple series resistor is the most common drive circuit. The resistor value (R) can be calculated using Ohm's Law: R = (V_supply - V_F) / I_F. Using the maximum V_F (2.4V) for calculation ensures the current does not exceed the desired value (e.g., 20mA) even with component tolerances. For a 5V supply: R = (5V - 2.4V) / 0.020A = 130 Ω. A standard 130Ω or 150Ω resistor would be suitable. For applications requiring constant brightness over a range of supply voltages or temperatures, a constant current driver is recommended.

7.3 Optical Design

The 60-degree viewing angle provides a wide beam, suitable for front-panel indicators. For applications requiring a narrower or differently shaped beam, secondary optics (lenses or light pipes) can be used. The stackable feature allows designers to create multi-LED arrays for bargraphs or custom patterns without complex mechanical holders.

8. Technical Comparison and Advantages

Compared to older incandescent indicator lamps, this LED offers significantly lower power consumption, much longer lifetime, higher shock and vibration resistance, and faster response time. Within the LED indicator market, its key differentiators are the stackable design for easy assembly of arrays, comprehensive environmental compliance (RoHS, REACH, Halogen-Free), and the combination of good luminous intensity with low forward voltage, which reduces power loss and heat generation. The plastic holder array design simplifies mounting on panels up to a specified thickness, reducing assembly time and cost.

9. Frequently Asked Questions (FAQ)

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength (λ_p) is the wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λ_d) is the single wavelength of monochromatic light that matches the perceived color of the LED light most closely. For visual indicators, dominant wavelength is more relevant to the human eye's perception of color.

Q: Can I drive this LED at 30mA for brighter output?
A: No. The Absolute Maximum Rating for continuous forward current is 25 mA. Exceeding this rating, even if the LED initially works, will significantly reduce its lifespan and may cause catastrophic failure due to overheating. Always operate within the specified limits.

Q: Why is the minimum distance of 3mm from the solder joint to the epoxy bulb so important?
A: This distance prevents excessive heat from the soldering process from traveling up the lead and damaging the sensitive semiconductor die inside the epoxy package or causing thermal stress cracks in the epoxy itself.

Q: How does the stackable feature work?
A> The plastic holder of the LED array is designed with interlocking features that allow multiple units to be snapped together either side-by-side (horizontally) or end-to-end (vertically), creating custom clusters without additional hardware.

10. Practical Use Case Example

Scenario: Designing a 5-level battery charge indicator for a portable device.
Five A1844B/4SYG/S530-E2 LEDs can be used in a vertical stack. A microcontroller monitors the battery voltage. Based on predefined voltage thresholds, it turns on a corresponding number of LEDs (e.g., one LED for 20% charge, all five for 100% charge). The stackable design allows them to be pre-assembled into a single compact module, which is then mounted into a slot on the device's case. The low forward voltage and current minimize the power drawn from the battery being monitored. The yellow-green color is chosen for high visibility under various lighting conditions. The drive circuit would use the microcontroller's GPIO pins, each connected to an LED via a current-limiting resistor calculated for the device's operating voltage (e.g., 3.3V or 5V).

11. Operating Principle

This LED is a semiconductor diode based on AlGaInP (Aluminum Gallium Indium Phosphide) material. When a forward voltage exceeding its turn-on voltage (approximately 1.7-2.4V) is applied, electrons and holes recombine in the active region of the semiconductor, releasing energy in the form of photons (light). The specific composition of the AlGaInP alloy determines the bandgap energy, which in turn dictates the wavelength (color) of the emitted light—in this case, yellow-green. The epoxy lens serves to protect the semiconductor die, shape the light output beam, and enhance light extraction efficiency.

12. Industry Trends and Context

Indicator LEDs like the A1844B/4SYG/S530-E2 represent a mature and highly optimized segment of the optoelectronics market. Current trends focus on increasing efficiency (more light output per watt), improving color consistency through tighter binning, and enhancing reliability under harsh conditions (higher temperature, humidity). There is also a strong drive towards simplifying assembly, as seen in this product's stackable and easy-mount features, to reduce manufacturing costs. The emphasis on halogen-free and full RoHS/REACH compliance reflects the electronics industry's global shift towards environmentally sustainable manufacturing and products. While basic indicator functions remain stable, integration with smart systems and the use of programmable multi-color LEDs are expanding the role of simple indicators in user interfaces.