LTD-6402JS-02 LED Display Datasheet - 0.56-inch Digit Height - AlInGaP Yellow - 2.6V Forward Voltage - Low Power - English Technical Documentation

1. Product Overview

The LTD-6402JS-02 is a high-performance, low-power seven-segment display module designed for applications requiring clear numeric readouts. Its primary function is to provide a highly legible, reliable, and energy-efficient display solution. The core advantage of this device lies in its utilization of advanced Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor technology for the LED chips, which offers superior brightness and efficiency compared to older technologies like standard Gallium Phosphide (GaP). The device is categorized for luminous intensity, ensuring consistent brightness levels across production batches. Its target market includes industrial instrumentation, consumer electronics, test and measurement equipment, and any embedded system where a compact, bright, and low-power numeric display is required.

2. Technical Parameter Deep Dive

2.1 Optoelectrical Characteristics

The optoelectrical performance is defined at a standard ambient temperature (Ta) of 25°C. The key parameter, Average Luminous Intensity (Iv), has a typical value of 700 µcd at a forward current (IF) of just 1mA per segment, highlighting its exceptional low-current capability. The Peak Emission Wavelength (λp) is typically 588 nm, and the Dominant Wavelength (λd) is 587 nm, firmly placing the emitted light in the yellow region of the visible spectrum. The Spectral Line Half-Width (Δλ) is 15 nm, indicating a relatively pure color emission. A critical parameter for multi-digit or multi-segment uniformity is the Luminous Intensity Matching Ratio (IV-m), which is specified at a maximum of 2:1 when segments are driven at 10mA, ensuring acceptable visual consistency.

2.2 Electrical Parameters

The electrical characteristics define the operating limits and conditions. The Absolute Maximum Ratings specify a Continuous Forward Current per segment of 25 mA, derating linearly from 25°C. The device can handle a Peak Forward Current of 100 mA under pulsed conditions (1/10 duty cycle, 0.1ms pulse width). The maximum Reverse Voltage per segment is 5V. Under typical operating conditions, the Forward Voltage per segment (VF) ranges from 2.05V to 2.6V at IF=20mA. The Reverse Current (IR) is a maximum of 100 µA at VR=5V. The Power Dissipation per segment is rated at 75 mW.

2.3 Thermal and Environmental Specifications

The device is rated for an Operating Temperature Range of -35°C to +105°C, with an identical Storage Temperature Range. This wide range makes it suitable for harsh environments. For assembly, the maximum solder temperature is 260°C for a maximum duration of 3 seconds, measured at 1.6mm (1/16 inch) below the seating plane of the component, which is a standard guideline for wave or reflow soldering processes.

3. Binning System Explanation

The datasheet explicitly states that the device is "Categorized for Luminous Intensity." This indicates a binning or sorting process based on measured light output. While specific bin codes are not provided in this document, this practice ensures that customers receive displays with consistent brightness levels. Typically, such categorization involves testing each unit at a specified current (e.g., 10mA or 20mA) and grouping them into bins based on predefined intensity ranges (e.g., 400-600 µcd, 600-800 µcd). This allows designers to select a bin that meets their specific brightness requirements and ensures visual uniformity in multi-digit displays.

4. Performance Curve Analysis

While the specific graphs are not detailed in the provided text, typical performance curves for such a device would include several key plots. The Current vs. Forward Voltage (I-V) Curve would show the exponential relationship, helping designers understand the voltage requirements at different drive currents. The Luminous Intensity vs. Forward Current (L-I Curve) is crucial, showing how light output increases with current, often in a near-linear relationship within the operating range, before potentially saturating. Luminous Intensity vs. Ambient Temperature curves would demonstrate the derating of light output as temperature increases, which is vital for high-temperature applications. Finally, a Spectral Distribution Curve would visually represent the peak wavelength and spectral width, confirming the yellow color point.

5. Mechanical and Packaging Information

5.1 Package Dimensions

The device features a standard dual-digit seven-segment display package. All dimensions are provided in millimeters with a general tolerance of ±0.25 mm (0.01"). The key dimension is the digit height, specified as 0.56 inches (14.22 mm). The detailed mechanical drawing would include the overall length, width, and height of the package, the spacing between digits, the segment dimensions, and the position and diameter of the mounting pins.

5.2 Pinout and Polarity Identification

The LTD-6402JS-02 is a Common Anode configuration device. It has two independent common anode pins: Pin 12 for Digit 1 and Pin 9 for Digit 2. This allows for separate multiplexing of each digit. The segment cathodes (A through G, plus Decimal Point) are shared across both digits. For example, Pin 11 is the cathode for segment 'A' for both Digit 1 and Digit 2. Pins 6 and 8 are noted as "No Connection" (NC). The right-hand decimal point (D.P.) is included and controlled via Pin 3. Correct identification of the common anode is critical for proper circuit design to provide a current source to the common pin and sink current through the individual segment pins.

6. Soldering and Assembly Guidelines

The primary guideline provided is the solder temperature limit: a maximum of 260°C for a maximum of 3 seconds, measured 1.6mm below the seating plane. This is a standard JEDEC recommendation for through-hole components to prevent damage to the LED chip, wire bonds, or plastic package. For assembly, standard wave soldering or selective soldering processes are applicable. It is recommended to follow standard IPC guidelines for cleaning to avoid flux residue on the light-gray face, which could affect contrast and appearance. Proper handling to avoid mechanical stress on the pins is also advised.

7. Packaging and Ordering Information

The part number is LTD-6402JS-02. The "JS" suffix often denotes specific characteristics like color and package style. The "02" may indicate a revision or specific bin. The device likely comes in standard anti-static tubes or trays for automated assembly. The datasheet reference is Spec No.: DS30-2000-040. Designers should always verify the exact packaging (e.g., quantity per tube, tubes per box) with the supplier or distributor at the time of ordering.

8. Application Suggestions

8.1 Typical Application Scenarios

This display is ideal for any application requiring one or two bright, easy-to-read digits. Common uses include: panel meters for voltage, current, or temperature; digital clocks and timers; scoreboard modules; appliance control panels (e.g., microwave ovens, washing machines); test equipment readouts; and industrial control system status indicators.

8.2 Design Considerations

Current Limiting: As a common anode device, the anode pins should be connected to a positive voltage supply through a current-limiting scheme. Each segment cathode pin must be connected to a current sink, typically a microcontroller I/O pin or a driver IC. External current-limiting resistors are absolutely mandatory for each segment or common anode to prevent excessive current and destruction of the LEDs. The resistor value can be calculated using R = (Vcc - Vf) / If, where Vf is the forward voltage (use max 2.6V for reliability) and If is the desired forward current (e.g., 10-20mA for full brightness, 1-5mA for low power).

Multiplexing: For two-digit operation, the common anodes (Pins 9 and 12) are toggled rapidly while the corresponding segment data is applied to the shared cathode pins. This reduces the number of required driver pins from 15 (7 segments + DP per digit) to just 9 (7 segments + DP + 2 commons). A refresh rate above 60Hz is recommended to avoid visible flicker.

Viewing Angle: The datasheet claims a "Wide Viewing Angle," which is typical for LED seven-segment displays. This should be considered for the mechanical placement of the display within the end product's enclosure.

9. Technical Comparison

The key differentiator of the LTD-6402JS-02 is its use of AlInGaP on a non-transparent GaAs substrate for yellow emission. Compared to older GaP:Y (Gallium Phosphide doped with Nitrogen for yellow) technology, AlInGaP LEDs offer significantly higher luminous efficiency and brightness at the same current, better color purity, and superior performance over temperature. When compared to standard red GaAsP or GaP LEDs, the yellow color provides excellent contrast against a light-gray face and is often considered more visually pleasing and less straining in low-light conditions. Its low-current capability (down to 1mA per segment with usable brightness) gives it an advantage in battery-powered or energy-sensitive applications over displays that require 10-20mA for adequate visibility.

10. Frequently Asked Questions (FAQ)

Q: What is the difference between common anode and common cathode?
A: In a common anode display, all the anodes of the LEDs (segments) are connected together to a positive supply. You turn on a segment by connecting its cathode to ground (low logic). In a common cathode display, all cathodes are connected to ground, and you turn on a segment by applying a positive voltage to its anode. The LTD-6402JS-02 is a common anode device.

Q: Can I drive this display directly from a microcontroller pin?
A: You can sink current from the segment cathodes using a microcontroller pin configured as an output low, provided the pin's maximum current sink rating is not exceeded (check the MCU datasheet). However, you typically cannot source enough current from an MCU pin to drive the common anode directly for multiplexing. A transistor (e.g., a PNP bipolar or a P-channel MOSFET) is usually required to switch the higher common anode current for each digit.

Q: Why is there a 2:1 intensity matching ratio?
A> This means that the dimmest segment in a display will be no less than half as bright as the brightest segment under the same test conditions. This ratio ensures reasonable visual uniformity. For critical applications, selecting displays from the same intensity bin is recommended.

Q: What does "AlInGaP on a non-transparent GaAs substrate" mean?
A> The light-emitting layers are made of AlInGaP semiconductor material. This active layer is grown on a Gallium Arsenide (GaAs) wafer which does not transmit light. Therefore, light is emitted only from the top surface of the chip, which is a standard construction for high-brightness LEDs, contributing to the high contrast mentioned in the features.

11. Practical Application Example

Design Case: A Simple Two-Digit Voltmeter Readout.
Consider designing a 0-99V DC voltmeter display. A microcontroller with an analog-to-digital converter (ADC) reads the input voltage. The software scales the ADC value to a number between 0 and 99. To drive the LTD-6402JS-02:
1. The two common anode pins are connected to two separate I/O pins of the MCU via small PNP transistors (e.g., 2N3906). The bases are driven through current-limiting resistors.
2. The eight segment cathode pins (A-G and DP) are connected to eight MCU I/O pins, each with a series current-limiting resistor (e.g., 150Ω for ~20mA at a 5V supply, considering Vf~2.6V).
3. In the firmware, a timer interrupt is set for multiplexing. In one interrupt cycle, the MCU:
- Turns off both digit transistors.
- Calculates the 7-segment code for the tens digit.
- Outputs this code on the segment pins.
- Turns on the transistor for the tens digit common anode.
- Waits a short delay (e.g., 5ms).
- Repeats the process for the units digit.
This creates a persistent, flicker-free two-digit display showing the measured voltage.

12. Technology Principle Introduction

The LED chips in this display are based on Aluminium Indium Gallium Phosphide (AlInGaP), a III-V compound semiconductor. When a forward voltage is applied across the p-n junction of this material, electrons and holes are injected into the active region. Their recombination releases energy in the form of photons (light). The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material, which is engineered by precisely controlling the ratios of Aluminium, Indium, Gallium, and Phosphorus during crystal growth. The yellow color (~587-588 nm) is achieved with a specific composition. The "non-transparent GaAs substrate" acts as a mechanical support but absorbs any light emitted downward, forcing all useful light out through the top of the chip, enhancing the directionality and contrast of the display.

13. Technology Trends

While seven-segment displays remain a staple for numeric readouts, the broader trend in display technology is moving towards more integrated and versatile solutions. Dot-matrix OLED and LCD displays offer alphanumeric and graphical capabilities in similarly sized packages. However, for applications requiring extreme simplicity, reliability, wide temperature range, high brightness, and low cost per digit, LED seven-segment displays like the LTD-6402JS-02 continue to be highly relevant. The evolution within this segment itself focuses on increasing efficiency (more light per mA), improving viewing angles, reducing package size (SMD versions), and expanding color options. The use of AlInGaP, as seen here, represents a significant step in efficiency over older technologies and remains a standard for high-performance red, orange, and yellow LEDs.