LTA-1000KR LED Display Datasheet - Rectangular Light Bar - Super Red Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTA-1000KR is a solid-state light-emitting diode (LED) display module designed as a ten-segment rectangular light bar. Its primary function is to provide a large, bright, and uniform area of illumination for applications requiring a continuous visual indicator or light source. The device is engineered for reliability and efficiency, utilizing advanced semiconductor materials to deliver consistent performance.

1.1 Core Advantages and Target Market

The key advantages of this product include its large and uniform light-emitting surface, which is ideal for status indicators, panel illumination, or backlighting where a distinct rectangular pattern is desired. It operates with a low power requirement, contributing to energy-efficient system design. The high brightness and contrast ratio ensure excellent visibility even in well-lit environments. Its solid-state construction offers superior reliability and longevity compared to traditional incandescent or fluorescent indicators, with no filaments to break or gases to degrade. The device is categorized for luminous intensity, allowing for consistent brightness matching in production. Furthermore, it complies with lead-free packaging requirements, aligning with modern environmental regulations (RoHS). This combination of features makes it suitable for industrial control panels, instrumentation, consumer electronics, and automotive dashboard applications where dependable and clear visual signaling is critical.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the device's electrical, optical, and physical parameters as defined in the datasheet.

2.1 Photometric and Optical Characteristics

The optical performance is central to the device's function. The LED chips used are based on AlInGaP (Aluminium Indium Gallium Phosphide) technology on a non-transparent GaAs substrate, which is known for high efficiency in the red/orange wavelength spectrum. The typical peak emission wavelength (λp) is 639 nm when driven at a forward current (IF) of 20 mA, placing it in the "Super Red" color range. The dominant wavelength (λd) is specified at 631 nm. The spectral line half-width (Δλ) is 20 nm, indicating a relatively narrow band of emitted light, which contributes to color purity.

The average luminous intensity (Iv) per segment is a key parameter. Under a test condition of IF=1 mA, the intensity ranges from a minimum of 200 μcd to a typical value of 675 μcd. The luminous intensity matching ratio between similar light areas is specified as 2:1 maximum, which is important for ensuring uniform appearance across all ten segments when they are illuminated simultaneously.

2.2 Electrical Parameters and Absolute Maximum Ratings

Understanding the electrical limits is crucial for reliable circuit design. The absolute maximum ratings define the stress limits beyond which permanent damage may occur.

• Power Dissipation per Segment: 70 mW maximum. This is the maximum power that can be safely dissipated as heat by a single LED segment.
• Continuous Forward Current per Segment: 25 mA maximum at 25°C. This rating derates linearly at 0.33 mA/°C as the ambient temperature (Ta) increases above 25°C. Designers must calculate the reduced maximum current at their application's highest operating temperature.
• Peak Forward Current per Segment: 90 mA maximum, but only under pulsed conditions (1/10 duty cycle, 0.1 ms pulse width). This allows for brief over-driving to achieve higher instantaneous brightness.
• Forward Voltage per Segment (VF): Typically 2.6 V at IF=20 mA, with a maximum of 2.6 V. The minimum is 2.0 V. This voltage drop is important for calculating series current-limiting resistor values.
• Reverse Voltage per Segment: 5 V maximum. Exceeding this can damage the LED junction.
• Reverse Current per Segment (IR): 100 μA maximum when a reverse voltage (VR) of 5 V is applied.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +105°C. The storage temperature range is identical. This wide range ensures functionality in harsh environments. The derating of forward current with temperature (0.33 mA/°C) is a direct consequence of the LED's thermal characteristics; higher temperatures reduce the efficiency and maximum safe operating current. The soldering condition specified is a wave or reflow process where the package body temperature does not exceed 260°C for 3 seconds, measured 1/16 inch (approximately 1.6 mm) below the seating plane. This guideline is critical for assembly to prevent thermal damage to the plastic package or the internal wire bonds.

3. Mechanical and Packaging Information

3.1 Physical Dimensions and Construction

The device is described as a rectangular light bar. The package has a gray face and white segments, which likely enhances contrast by providing a dark background for the lit segments. The exact dimensions are provided in a drawing (referenced in the datasheet but not detailed in the text). All dimensions are in millimeters, with standard tolerances of ±0.25 mm unless otherwise noted. A specific tolerance for pin tip shift is ±0.4 mm, which is important for PCB footprint design and automated assembly.

3.2 Pin Connection and Internal Circuit

The LTA-1000KR has a 20-pin configuration. The pinout is clearly defined: Pins 1 through 10 are the anodes for segments A through K (note: 'I' is skipped, using J and K). Pins 11 through 20 are the corresponding cathodes in reverse order (Cathode K to Cathode A). This arrangement suggests a common-cathode style connection for each segment, but with individual access to both the anode and cathode of each LED. This provides maximum flexibility for multiplexing or individual segment control. An internal circuit diagram is referenced, typically showing ten independent LED elements.

4. Application Guidelines and Design Considerations

4.1 Typical Application Scenarios

This light bar is designed for applications requiring a linear array of bright indicators. Potential uses include:

• Level Indicators: For signal strength, volume, pressure, or temperature gauges where the illuminated length corresponds to a value.
• Progress Bars: In instrumentation or consumer devices to show completion status.
• Backlighting: For edge-lit panels or signage where uniform rectangular illumination is needed.
• Industrial Status Displays: On control panels to show machine state or alarm conditions across multiple channels.

4.2 Circuit Design and Driving Considerations

To operate the LTA-1000KR safely and effectively, several design rules must be followed:

1. Current Limiting: LEDs are current-driven devices. A series resistor must be used with each segment (or a current-regulated driver circuit) to limit the forward current to a safe value, typically at or below the 25 mA continuous rating. The resistor value is calculated using Ohm's Law: R = (Vsupply - VF) / IF, where VF is the forward voltage of the LED (use max value for worst-case current calculation).
2. Thermal Management: While the power dissipation is low per segment (70 mW max), the total for ten segments can be 700 mW. Adequate PCB copper area or other heat sinking may be necessary if all segments are driven continuously at high current, especially in high ambient temperatures.
3. Multiplexing: The individual anode and cathode access makes the device well-suited for multiplexed driving schemes. This reduces the number of required microcontroller I/O pins. Care must be taken to ensure the peak current during the multiplexing pulse does not exceed the 90 mA rating, and the average current over time respects the continuous rating.
4. Reverse Voltage Protection: In circuits where reverse voltage transients are possible, external protection diodes may be necessary, as the LED's own reverse voltage rating is only 5V.

4.3 Assembly and Handling

Adherence to the soldering profile (260°C max for 3 seconds) is mandatory to prevent package cracking or delamination. Standard ESD (Electrostatic Discharge) precautions should be observed during handling and assembly, as LED chips are sensitive to static electricity. Storage should be within the specified temperature and humidity ranges to prevent moisture absorption, which can cause "popcorning" during reflow soldering.

5. Performance Analysis and Technical Comparison

5.1 Analysis of Key Parameters

The use of AlInGaP technology is a significant factor. Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, AlInGaP offers substantially higher luminous efficiency, resulting in greater brightness for the same drive current. The non-transparent GaAs substrate helps in directing light upward, improving the useful light output from the top surface. The specified luminous intensity matching ratio of 2:1 is a standard grade for such displays, ensuring acceptable visual uniformity. Designers requiring tighter uniformity would need to implement electrical calibration or select binned parts if available.

5.2 Comparison with Alternative Solutions

Compared to a cluster of discrete LEDs, this integrated light bar provides a more uniform and mechanically robust solution, with simplified assembly (one component vs. ten). Compared to vacuum fluorescent or electroluminescent displays, LEDs offer much longer lifetime, lower operating voltage, and no risk of gas leakage or phosphor degradation. The main trade-off might be viewing angle and the specific color point, which is fixed in the deep red spectrum for this model.

6. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive all ten segments at 25 mA simultaneously?

A: Yes, electrically you can, as each segment is independent. However, you must consider the total power dissipation (up to 700 mW) and ensure the PCB and ambient environment can handle the resulting heat to maintain reliability, especially near the upper temperature limit.

Q: What is the difference between peak wavelength and dominant wavelength?

A: Peak wavelength (λp=639nm) is the wavelength at which the emission spectrum has its maximum intensity. Dominant wavelength (λd=631nm) is the single wavelength of monochromatic light that would appear to have the same color to the human eye. The difference is due to the shape of the LED's emission spectrum.

Q: How do I interpret the "Luminous intensity is measured with... CIE eye-response curve" note?

A: This note confirms that the intensity values (in microcandelas, μcd) are photometric units, weighted by the standard human photopic (daylight-adapted) visual sensitivity curve. This makes the numbers meaningful for predicting perceived brightness, as opposed to radiometric units (watts) which measure total light power irrespective of color.

Q: The pinout shows individual anodes and cathodes. Can I wire it as a common-anode or common-cathode display?

A: The physical pinout is fixed. To simulate a common-cathode display, you would connect all cathode pins (11-20) together on your PCB. To simulate a common-anode display, you would connect all anode pins (1-10) together. The provided configuration offers the flexibility to implement either in hardware.

7. Design and Usage Case Study

Scenario: Designing a Battery Charge Level Indicator

A designer is creating a charger for a tool battery. They want a 10-segment bar graph to show charge level from 0% to 100%. The LTA-1000KR is selected for its bright red color and rectangular segment shape, which is easy to read.

Implementation: The system microcontroller has limited I/O pins. The designer uses a multiplexing scheme. They connect the ten anodes (pins 1-10) to ten individual microcontroller pins configured as outputs. They connect the ten cathodes (pins 11-20) together and sink this common node through a single N-channel MOSFET controlled by another microcontroller pin. To illuminate a segment, its corresponding anode pin is set high (through a current-limiting resistor), and the common cathode MOSFET is turned on. The microcontroller rapidly cycles through each segment (e.g., 1ms per segment). The peak current per segment is set to 20 mA via the resistor calculation: R = (5V - 2.6V) / 0.020A = 120 Ohms (use 120Ω or 150Ω standard value). The average current per segment is 2 mA (20 mA * 1/10 duty cycle), well within the continuous rating. The display appears uniformly lit due to persistence of vision. The brightness is easily adjusted in software by varying the duty cycle of the multiplexing.

8. Technical Principle Introduction

Light Emitting Diodes (LEDs) are semiconductor p-n junction devices. When a forward voltage is applied, electrons from the n-type region and holes from the p-type region are injected into the junction region. When these charge carriers recombine, energy is released. In materials like AlInGaP, this energy is released primarily as photons (light) rather than heat. The specific wavelength (color) of the emitted light is determined by the bandgap energy of the semiconductor material, which is engineered during the crystal growth process by adjusting the ratios of aluminium, indium, gallium, and phosphorus. The non-transparent substrate absorbs downward-emitted light, improving overall efficiency by reducing internal loss and encouraging light to exit from the top surface of the chip. The gray face and white segments of the package act as a reflector and diffuser, respectively, to create a uniform rectangular appearance from the discrete LED chips mounted underneath.

9. Technology Trends and Context

The LTA-1000KR represents a mature LED display technology. The broader industry trend has been towards higher efficiency and greater integration. While discrete LED light bars like this one remain vital for specific form factors, newer technologies are emerging. Surface-mount device (SMD) LED arrays offer even smaller footprints and are better suited for automated pick-and-place assembly. Furthermore, the development of organic LEDs (OLEDs) and micro-LEDs enables fully addressable, flexible, and ultra-high-resolution displays. However, for applications requiring simple, robust, high-brightness indicators in a specific bar format, inorganic LED arrays like the AlInGaP-based LTA-1000KR continue to offer an optimal balance of performance, reliability, and cost. The move to lead-free packaging, as seen in this device, reflects the industry-wide shift towards environmentally sustainable manufacturing processes driven by global regulations like RoHS and REACH.