LTS-5001AJD LED Display Datasheet - 0.56-inch Digit Height - Hyper Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-5001AJD is a single-digit, seven-segment LED display module designed for numeric readout applications. It features a 0.56-inch (14.22 mm) digit height, providing clear and legible characters suitable for a variety of electronic equipment. The device utilizes advanced AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology to produce a hyper red emission. The package presents a gray face with white segments, enhancing contrast and readability. This display is categorized as a common anode type, which is a standard configuration for simplifying drive circuitry in multiplexed applications.

1.1 Core Advantages and Target Market

The primary advantages of the LTS-5001AJD include its high brightness output, excellent character appearance with continuous uniform segments, and a wide viewing angle. Its low power requirement and solid-state reliability make it a durable choice. The device is categorized for luminous intensity, ensuring consistency in brightness levels. It is constructed with a lead-free package, complying with RoHS (Restriction of Hazardous Substances) directives. This display is intended for ordinary electronic equipment found in office, communication, and household applications where reliable numeric indication is required.

2. Technical Specifications and Objective Interpretation

2.1 Photometric and Electrical Characteristics

The key performance parameters are defined at an ambient temperature (Ta) of 25°C. The average luminous intensity per segment has a typical value of 700 ucd (microcandelas) when driven at a forward current (IF) of 1 mA, with a minimum specified value of 320 ucd. The peak emission wavelength (λp) is 650 nm, and the dominant wavelength (λd) is 639 nm at IF=20mA, placing it firmly in the hyper red region of the spectrum. The spectral line half-width (Δλ) is 20 nm. The forward voltage (VF) per LED chip ranges from 2.10V to 2.60V (typical 2.60V) at IF=20mA. The reverse current (IR) per segment is specified at a maximum of 100 µA when a reverse voltage (VR) of 5V is applied, though continuous operation under reverse bias is not permitted. Luminous intensity matching between segments is maintained within a 2:1 ratio under similar test conditions.

2.2 Absolute Maximum Ratings and Thermal Considerations

The device has strict operational limits. The maximum power dissipation per segment is 70 mW. The peak forward current per segment is 90 mA, but this is only permissible under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). The continuous forward current per segment is derated from 25 mA at 25°C at a rate of 0.33 mA/°C. The absolute maximum reverse voltage per segment is 5V. The operating and storage temperature range is from -35°C to +85°C. Exceeding these ratings, particularly in current or temperature, may lead to severe light output degradation or permanent device failure. The driving circuit must be designed to protect against reverse voltages and transient spikes during power cycling.

3. Binning and Categorization System

The datasheet indicates that the LTS-5001AJD is \"categorized for luminous intensity.\" This implies that units are sorted (binned) based on their measured light output at a standard test current. This process ensures that displays used together in a multi-digit application will have consistent brightness, avoiding noticeable variations between digits. While specific bin codes are not detailed in this excerpt, the 2:1 intensity matching ratio specification defines the maximum allowable variation between segments within a single device.

4. Performance Curve Analysis

While the specific graphical data for curves like the forward current vs. forward voltage (IV curve) or luminous intensity vs. temperature are not provided in the text excerpt, their inclusion in a typical datasheet section titled \"Typical Electrical / Optical Characteristics Curves\" is standard. These curves are critical for design engineers. The IV curve helps in selecting the appropriate current-limiting resistor or designing constant-current drivers by showing the non-linear relationship between voltage and current. Temperature characteristic curves would show how luminous intensity and forward voltage shift with changes in the junction temperature, which is vital for designing stable performance over the entire operating temperature range.

5. Mechanical and Package Information

5.1 Physical Dimensions and Tolerances

All package dimensions are provided in millimeters. Standard tolerances are ±0.25mm unless otherwise specified. Key quality control notes include limits on foreign materials (≤10 mils) and bubbles (≤10 mils) within the segment area, bending of the reflector (≤1% of its length), and surface ink contamination (≤20 mils). The pin tip shift tolerance is ±0.40 mm. For PCB design, a hole diameter of 1.0 mm is recommended for the device's pins to ensure proper fit and solderability.

5.2 Pin Connection and Polarity

The LTS-5001AJD is a common anode display with 10 pins. The internal circuit diagram and pin connection table define the mapping: Pins 3 and 8 are the common anodes. The cathodes for segments E, D, C, Decimal Point, B, A, F, and G are connected to pins 1, 2, 4, 5, 6, 7, 9, and 10 respectively. Correct identification of anode and cathode pins is crucial to prevent reverse bias and ensure proper circuit operation.

6. Soldering and Assembly Guidelines

6.1 Soldering Profiles

Two soldering methods are addressed. For auto (wave) soldering, the condition is 1/16 inch (approximately 1.6 mm) below the seating plane for 5 seconds at a maximum temperature of 260°C. For manual soldering, the iron tip should be 1/16 inch below the seating plane, with a soldering time not exceeding 5 seconds at a temperature of 350°C ±30°C. Adherence to these time and temperature limits is essential to prevent thermal damage to the LED chips and the plastic package.

6.2 Storage and Handling

While specific storage conditions beyond the temperature range are not detailed, standard ESD (Electrostatic Discharge) precautions should be observed when handling the device. The leads should be kept clean and free from oxidation prior to soldering to ensure good solderability, as referenced in the reliability test for solderability (SA).

7. Application Recommendations

7.1 Typical Application Scenarios

This display is suited for applications requiring a single, bright numeric digit. Examples include instrument panels, test equipment, appliance controls (e.g., microwave ovens, washing machines), point-of-sale terminals, and industrial counters. Its common anode configuration makes it compatible with standard multiplexing techniques used to drive multi-digit displays efficiently with a microcontroller.

7.2 Design Considerations and Circuit Protection

Constant current driving is strongly recommended over constant voltage driving to ensure consistent luminous intensity across segments and over temperature variations. The circuit design must account for the full range of forward voltage (VF, 2.10V to 2.60V) to guarantee the intended drive current is delivered to all segments. The safe operating current must be derated based on the maximum expected ambient temperature. Crucially, the driving circuit must incorporate protection against reverse voltages and voltage transients that can occur during power-up or shutdown sequences, as the absolute maximum reverse voltage is only 5V. A series resistor is typically used with a constant voltage source, while dedicated LED driver ICs or transistor-based constant current sources offer better performance.

8. Reliability and Testing

The device undergoes a comprehensive suite of reliability tests based on military (MIL-STD), Japanese industrial (JIS), and internal standards. These include operational life testing (1000 hours at room temperature), high temperature/humidity storage (500 hours at 65°C/90-95% RH), high and low temperature storage (1000 hours each), temperature cycling, thermal shock, solder resistance, and solderability tests. These tests validate the device's robustness under various environmental and assembly stresses, ensuring long-term performance in the field.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength (650nm) and dominant wavelength (639nm)?

A: Peak wavelength is the point of maximum power in the emitted spectrum. Dominant wavelength is the single wavelength of monochromatic light that would match the perceived color of the LED. For red LEDs, the dominant wavelength is often slightly shorter than the peak wavelength and is more relevant for color specification.

Q: Can I drive this display with a 5V supply directly?

A: No. With a typical forward voltage of 2.6V per segment, connecting a 5V source directly would cause excessive current, destroying the LED. A current-limiting resistor must be used. The resistor value is calculated as R = (Vsupply - Vf) / If. For a 5V supply, 20mA current, and 2.6V Vf: R = (5 - 2.6) / 0.02 = 120 Ohms.

Q: Why is the continuous current derated with temperature?

A: As the LED junction temperature increases, its ability to dissipate heat decreases. Derating the current prevents the junction temperature from exceeding its maximum limit, which would accelerate light output degradation and reduce operational lifespan.

Q: What does \"common anode\" mean for my circuit design?

A: In a common anode display, all the anodes of the LED segments are connected together to a common pin (or two pins, 3 and 8, in this case). To illuminate a segment, its cathode must be connected to a lower voltage (ground) while the common anode is held at a positive voltage. This is the opposite of a common cathode display.

10. Design and Usage Case Study

Consider designing a simple digital voltmeter display using a microcontroller. The microcontroller's I/O pins lack sufficient current to drive the LEDs directly. A practical design would use a dual-component approach: 1) A transistor array (e.g., ULN2003) to sink current from the segment cathodes, controlled by the microcontroller. 2) A PNP transistor or a dedicated digit driver to source current to the common anode pin(s), enabling multiplexing. The microcontroller would cycle through turning on one digit at a time (by enabling its common anode) while outputting the pattern for that digit on the segment lines. A refresh rate above 60 Hz would ensure a flicker-free display. Current-limiting resistors would be placed on either the cathode or anode side. This design efficiently controls brightness and minimizes the number of required microcontroller pins.

11. Operational Principle

The LTS-5001AJD operates on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's turn-on threshold is applied, electrons from the n-type AlInGaP layer recombine with holes from the p-type layer. This recombination event releases energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, hyper red. The non-transparent GaAs substrate helps reflect light upward, improving overall light extraction efficiency from the top of the chip.

12. Technology Trends and Context

AlInGaP technology represents a mature and highly efficient solution for red, orange, and yellow LEDs. Compared to older technologies like GaAsP, AlInGaP offers significantly higher luminous efficacy and better temperature stability. The trend in display components like this is towards higher efficiency (more light output per watt), which allows for lower power consumption and reduced heat generation. There is also a continuous drive for improved consistency in brightness and color (tighter binning) across production batches. While this is a through-hole component, the broader industry trend is towards surface-mount device (SMD) packages for automated assembly, though through-hole displays remain popular for prototyping, repair, and certain industrial applications where mechanical robustness is paramount.