LTS-5824SW LED Display Datasheet - 0.56-inch Digit Height - White Color - 3.2V Forward Voltage - 35mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-5824SW is a single-digit, seven-segment plus decimal point LED display module. It is designed for applications requiring clear, bright numeric readouts. The device utilizes InGaN (Indium Gallium Nitride) white LED chips mounted on a transparent substrate, which contributes to its optical performance. The display features a black face for high contrast and white segments for clear illumination.

1.1 Core Features and Advantages

The display offers several key advantages for integration into electronic systems:

• Digit Size: A 0.56-inch (14.25 mm) digit height provides excellent readability from a distance.
• Optical Quality: It boasts excellent segment uniformity, ensuring consistent brightness across all lit segments.
• Efficiency: The device has a low power requirement, making it suitable for battery-powered or energy-conscious applications.
• Performance: High brightness and high contrast ratio ensure the display is easily visible under various ambient lighting conditions.
• Viewing Angle: A wide viewing angle of 130 degrees (2θ1/2) allows the display to be read from off-axis positions.
• Reliability: As a solid-state device, it offers high reliability and long operational life compared to mechanical displays.
• Quality Control: The LEDs are binned for luminous intensity, providing predictable and consistent brightness levels.
• Environmental Compliance: The package is lead-free and compliant with RoHS (Restriction of Hazardous Substances) directives.

1.2 Target Market and Applications

This LED display is intended for use in ordinary electronic equipment. Typical application areas include office automation equipment (e.g., calculators, copiers), communication devices, household appliances, instrumentation panels, and consumer electronics where clear numeric indication is required. It is designed for applications where exceptional reliability under standard operating conditions is sufficient.

2. Technical Parameters Deep Dive

This section provides a detailed, objective interpretation of the key electrical and optical parameters specified for the LTS-5824SW.

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operating the display continuously at or near these limits is not recommended.

• Power Dissipation per Segment: 35 mW maximum. Exceeding this can lead to overheating and accelerated degradation.
• Peak Forward Current per Segment: 50 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). This is for short-term stress testing, not continuous operation.
• Continuous Forward Current per Segment: 10 mA at 25°C. This current derates linearly at 0.22 mA/°C as ambient temperature (Ta) increases above 25°C. For example, at 50°C, the maximum recommended continuous current would be approximately 10 mA - (0.22 mA/°C * 25°C) = 4.5 mA.
• Operating Temperature Range: -20°C to +80°C. The device is guaranteed to function within this ambient temperature range.
• Storage Temperature Range: -40°C to +85°C.
• Solder Reflow Condition: The device can withstand soldering at 260°C for 3 seconds, with the condition that the temperature measured 1/16 inch (approx. 1.6 mm) below the seating plane of the device does not exceed this rating.

2.2 Electrical & Optical Characteristics (Typical at 25°C)

These are the standard operating parameters measured under specific test conditions.

• Average Luminous Intensity (Iv): 71 µcd (microcandela) minimum, measured at a forward current (IF) of 5 mA using a sensor filtered to match the CIE photopic eye response curve.
• Forward Voltage per Segment (VF): Typically 3.2V, with a range from 2.7V to 3.2V at IF=5mA. This parameter has significant variation and is binned (see Section 3).
• Viewing Angle (2θ1/2): 130 degrees. This is the full angle at which the luminous intensity drops to half of its peak value.
• Chromaticity Coordinates: The typical color point is specified at CIE 1931 coordinates (x=0.339, y=0.3495) at IF=5mA. A tolerance of ±0.01 is applied to these coordinates, and the actual hue is also binned.
• Reverse Current per Segment (IR): Maximum 10 µA at a reverse voltage (VR) of 5V. Important: This test condition is for characterization only; the device is not designed to operate under continuous reverse bias.
• Luminous Intensity Matching Ratio: The ratio of brightness between segments in a similar lit area is 2:1 maximum. This ensures visual consistency.
• Cross Talk: Specified as ≤ 2.5%. This refers to unwanted illumination or electrical interference between adjacent segments.

3. Binning System Explanation

To ensure consistency in production, LEDs are sorted into bins based on key parameters. The LTS-5824SW uses bins for Forward Voltage (VF), Luminous Intensity (IV), and Hue (color).

3.1 Forward Voltage (VF) Binning

LEDs are grouped into bins with a 0.1V tolerance on each bin. This allows circuit designers to account for VF variation when designing current-limiting circuitry. Bins range from V1 (2.55-2.65V) to V6 (3.05-3.15V).

3.2 Luminous Intensity (IV) Binning

LEDs are binned for brightness with a ±15% tolerance per bin. The specified bins are Q (71.0-112.0 µcd), R (112.0-180.0 µcd), and E (180.0-280.0 µcd), all measured at IF=5mA.

3.3 Hue (Color) Binning

The white color point is controlled through binned chromaticity coordinates on the CIE 1931 diagram. Bins are defined by quadrilaterals in (x,y) space (e.g., S7-1, S7-2, S8-1, etc.), with a tolerance of ±0.01 on each coordinate. This ensures the white color is consistent within a defined range.

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet (e.g., Fig.6 for viewing angle), their typical implications are analyzed here.

4.1 Forward Current vs. Forward Voltage (IV Curve)

The LED's VF increases with IF in a non-linear, exponential manner typical of a diode. Operating at the recommended 5mA ensures stable performance within the specified VF range. Driving at higher currents increases brightness but also power dissipation and junction temperature, which can affect longevity.

4.2 Temperature Characteristics

The luminous output of an LED decreases as the junction temperature increases. The derating of continuous forward current (0.22 mA/°C above 25°C) is a direct result of this thermal relationship. Maintaining a lower operating temperature is crucial for maintaining brightness and lifespan.

4.3 Viewing Angle Pattern

The 130-degree viewing angle indicates a Lambertian or near-Lambertian emission pattern, where intensity is fairly uniform across a wide area before dropping off. This is ideal for displays that need to be viewed from various angles.

5. Mechanical & Package Information

5.1 Package Dimensions

The display has a standard single-digit 10-pin DIP (Dual In-line Package) footprint. Critical dimensional notes include:

• All dimensions are in millimeters with a general tolerance of ±0.25 mm unless specified otherwise.
• Pin tip shift tolerance is ±0.4 mm.
• Recommended PCB hole diameter for the pins is 0.9 mm.
• Quality criteria are defined for foreign material (≤10 mil), ink contamination (≤20 mil), bubbles in segments (≤10 mil), and bending of the reflector (≤1% of its length).

5.2 Pin Connection and Polarity

The LTS-5824SW is a common anode display. The internal circuit diagram shows individual LEDs for each segment (A-G and DP) with their anodes connected together to common pins (3 and 8). The cathodes of each segment are brought out to separate pins (1, 2, 4, 5, 6, 7, 9, 10). Pin 5 is specifically for the decimal point (DP). To illuminate a segment, the corresponding common anode pin(s) must be connected to a positive voltage supply (through a current-limiting resistor), and the segment's cathode pin must be pulled to ground (sinked).

6. Soldering & Assembly Guidelines

6.1 Reflow Soldering Parameters

The device can withstand a peak temperature of 260°C for 3 seconds during reflow soldering. It is critical that this temperature is measured at the specified point below the package body to avoid overheating the internal LED chips and plastic material.

6.2 Handling and Storage Precautions

• ESD (Electrostatic Discharge) Sensitivity: The InGaN LED chips are sensitive to ESD. Handling should be done with proper ESD precautions: use grounded wrist straps, work on grounded mats, and ensure all equipment is properly grounded.
• Storage Conditions: Store within the specified temperature range of -40°C to +85°C in a low-humidity environment to prevent moisture absorption.
• Mechanical Stress: Avoid applying force to the display body during assembly. Use suitable tools to prevent cracking or damaging the package.

7. Application Design Recommendations

7.1 Circuit Design Considerations

• Current Drive: Constant current driving is strongly recommended over constant voltage driving. This ensures consistent luminous intensity regardless of VF variations between units or temperature changes.
• Current Limiting Resistors: If using a voltage source with series resistors, the resistor value must be calculated based on the maximum VF from the binning table (up to 3.15V) to guarantee the desired current is never exceeded, even with a low-VF supply.
• Protection Circuits: The driving circuit should include protection against reverse voltages and transient voltage spikes during power-up/down sequences, as these can damage the LEDs.
• Thermal Management: Consider the maximum ambient temperature (Ta) of the application. The forward current must be derated accordingly to prevent overheating. Adequate PCB copper or other heat sinking for the common anode pins may help dissipate heat.

7.2 Environmental Considerations

• Avoid rapid temperature changes in high-humidity environments, as this can cause condensation on the display, potentially leading to electrical leakage or corrosion.
• Reverse bias should be strictly avoided in circuit design, as it can induce metal migration within the LED chip, increasing leakage current or causing a short circuit.

8. Frequently Asked Questions (Based on Technical Parameters)

8.1 What is the difference between "common anode" and "common cathode"?

This display is common anode. All segment LED anodes are tied together internally. To turn on a segment, you apply a positive voltage to the common anode pin(s) and connect the segment's cathode pin to ground. A common cathode display would have the cathodes tied together, requiring a ground connection on the common pin and a positive voltage applied to the individual anode pins to illuminate segments. The driving circuit (e.g., microcontroller port configuration) must match the display type.

8.2 Why is constant current drive recommended?

LED brightness is primarily a function of forward current (IF). The forward voltage (VF) can vary significantly from device to device (as shown in the binning table) and also changes with temperature. A constant voltage source with a fixed resistor will result in different currents (and thus brightness) as VF changes. A constant current driver maintains a precise IF, ensuring consistent brightness across all units and over temperature variations.

8.3 Can I drive it with a 5V microcontroller pin directly?

No, you should not connect it directly. At a typical VF of 3.2V, connecting a 5V supply directly to the LED (even through a microcontroller pin) would attempt to pass a very high current, likely destroying the LED segment and potentially damaging the microcontroller pin. You must always use a current-limiting resistor or a dedicated constant-current LED driver circuit.

8.4 How do I calculate the current-limiting resistor value?

Use Ohm's Law: R = (V_supply - VF_LED) / I_desired. Use the maximum VF from the datasheet (e.g., 3.15V for bin V6) for a worst-case design to ensure current never exceeds the limit. For a 5V supply and a desired current of 5mA: R = (5V - 3.15V) / 0.005A = 370 Ohms. You would then use the nearest standard value (e.g., 360 or 390 Ohms). The power rating of the resistor is P = I^2 * R = (0.005^2)*370 ≈ 0.00925W, so a standard 1/8W or 1/10W resistor is sufficient.

9. Practical Design Example

Scenario: Designing a simple digital timer display using a microcontroller.

1. Component Selection: Choose the LTS-5824SW for its readability and low power consumption.
2. Circuit Design: Use a common anode configuration. Connect common pins 3 and 8 to the positive supply rail (e.g., 5V) through a single current-limiting resistor sized for the total possible current (if all segments + DP are on). Alternatively, connect them directly to 5V if using individual segment resistors. Connect each cathode pin (1,2,4,5,6,7,9,10) to a separate GPIO pin on the microcontroller via a current-limiting resistor (e.g., 390Ω).
3. Microcontroller Programming: Configure the GPIO pins connected to the segment cathodes as outputs. To display a number, set the corresponding cathode pins to LOW (0V) to sink current and light those segments. Keep other cathode pins HIGH (open-drain/high-impedance). The common anode pins remain at 5V.
4. Multiplexing (for multiple digits): If driving multiple digits, a multiplexing technique can be used. Connect all corresponding segment cathodes together across digits, and control each digit's common anode individually. Rapidly cycle power to each digit's common anode while setting the segment pattern for that digit. The persistence of vision makes all digits appear lit simultaneously while drastically reducing the number of required microcontroller pins.

10. Technical Principles

The LTS-5824SW is based on InGaN semiconductor technology. When a forward voltage exceeding the diode's threshold 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 Indium Gallium Nitride layers determines the wavelength of the emitted light. A phosphor coating on the blue-emitting InGaN chip converts part of the blue light to longer wavelengths (yellow, red), mixing to produce the perceived white light. The transparent substrate allows for efficient light extraction. The seven-segment layout is a standardized pattern where individual LEDs (segments) can be selectively illuminated to form numeric characters (0-9) and some letters.

11. Industry Trends

The development of LED displays like the LTS-5824SW follows broader trends in optoelectronics. There is a continuous drive towards higher efficiency (more light output per watt of electrical input), which allows for lower power consumption and reduced heat generation. Advances in semiconductor materials and phosphor technology enable better color rendering and more consistent white points. Miniaturization is another trend, although for readability, digit size often has a lower practical limit. Integration is also key, with driver ICs increasingly incorporating more features like brightness control (PWM), fault detection, and serial communication interfaces (I2C, SPI) to simplify system design and reduce component count on the PCB.