LTS-2806CKR-P LED Digital Tube Datasheet - 0.28 Inch Digit Height - Super Red - 2.6V Forward Voltage - 70mW Power Consumption - Technical Documentation

1. Product Overview

LTS-2806CKR-P is a surface-mount device designed for single-digit numeric display. Its core function is to provide clear and reliable digital indication in a compact, modern package, suitable for automated assembly processes. A notable feature of this component is its light-emitting chip, which utilizes aluminum indium gallium phosphide semiconductor material grown on a gallium arsenide substrate. This material technology is chosen to generate high-efficiency light within the red to amber spectral range. Its appearance design incorporates a gray panel and white segment filter, a combination intended to enhance contrast and readability when the segments are illuminated.

1.1 Main Features and Target Applications

This display is designed for integration into consumer and industrial electronic devices where space, energy efficiency, and reliability are key considerations. Its 0.28-inch digit height strikes a balance between visibility and PCB space occupancy. The continuous, uniform segment design ensures consistency and a professional appearance of the characters. Key advantages include low power requirements, high brightness output, excellent contrast, and a wide viewing angle, making it suitable for various readout applications. It is categorized by luminous intensity to facilitate brightness matching in multi-digit applications and comes in a lead-free package compliant with the RoHS directive. Typical applications include instrument panels, home appliances, communication equipment, office automation devices, and various control panels requiring single-digit displays.

2. Technical Specifications and Objective Interpretation

LTS-2806CKR-P performance is defined by a set of absolute maximum ratings and standard electrical/optical characteristics. Understanding these parameters is crucial for reliable circuit design and long-term operation.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device and are not applicable for normal operating conditions. The maximum power dissipation per segment is 70 mW. The peak forward current rating per segment is 90 mA, but this is only permitted under specific pulse conditions: a duty cycle of 1/10 and a pulse width of 0.1 ms. The continuous forward current per segment is 25 mA at 25°C and derates linearly with increasing temperature. The operating and storage temperature range for the device is -35°C to +105°C. For hand soldering, the soldering iron tip should be held at 260°C, 1/16 inch below the mounting plane, for a maximum of 3 seconds.

2.2 Electrical and Optical Characteristics

These parameters are measured under standard test conditions and represent typical performance. Average luminous intensity is the primary indicator. At a forward current of 1 mA, the minimum intensity is 201 µcd, with a typical value of 650 µcd. At 10 mA, the typical intensity rises significantly to 8250 µcd. The typical forward voltage per chip is 2.6V at a test current of 20 mA, with a maximum of 2.6V. The typical peak emission wavelength is 639 nm, and the typical dominant wavelength is 631 nm, both measured at 20 mA, with the output light color clearly falling within the super red region. The spectral line half-width is 20 nm. The maximum reverse current per segment at a reverse voltage of 5V is 100 µA. It must be noted that this reverse voltage condition is for test purposes only; the device must not be operated continuously under reverse bias. At a drive current of 1 mA, the maximum luminous intensity matching ratio between segments is 2:1.

3. Binning and Performance Matching

The datasheet indicates that the LTS-2806CKR-P is "classified by luminous intensity." This refers to a binning process where manufacturing units are sorted based on their measured light output under a standard test current. This allows designers to select displays from the same or adjacent intensity bins to ensure uniform brightness across all digits in a multi-digit display, preventing noticeable segment brightness variations. While this summary does not detail the specific binning codes, this feature is crucial for applications requiring a consistent visual appearance.

4. Performance Curve Analysis

Although specific graphs are not reproduced in text, the datasheet references "Typical Electrical/Optical Characteristic Curves." These curves are invaluable to design engineers. They typically include a forward current vs. forward voltage curve, showing the diode's turn-on behavior. More importantly, they include a curve of luminous intensity versus forward current, which is a nonlinear relationship. This curve helps designers select the optimal drive current to achieve the desired brightness while managing power consumption and heat. Another key curve depicts luminous intensity versus ambient temperature, showing how light output decreases as temperature rises. This is crucial for designing systems to operate in high-temperature environments, ensuring sufficient brightness margin is included.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Tolerances

The LTS-2806CKR-P is offered in a surface-mount package. All critical dimensions are provided in millimeters. Unless otherwise specified, the general tolerance is ±0.25 mm. The datasheet also includes specific visual and mechanical quality standards: foreign material on segments must be ≤10 mils, ink contamination on the surface ≤20 mils, bubbles within segments ≤10 mils, reflector warpage must be ≤1% of its length, and plastic lead burrs must not exceed 0.1 mm. These standards ensure consistent physical quality and reliable mounting during assembly.

5.2 Internal Circuit and Pin Configuration

This device features an internal circuit diagram showing a common anode configuration. This means the anodes of all LED segments are internally connected together. The display has a total of 12 pins. The pin connection table is crucial for PCB layout: Pin 4 and Pin 9 are both common anode connections. The cathodes for segments A, B, C, D, E, F, G, and DP are connected to pins 8, 7, 5, 2, 3, 10, 12, and 6, respectively. Pins 1 and 11 are marked as "No Connection". This pin arrangement must be strictly followed to ensure correct segment illumination.

6. Soldering, Assembly, and Operation Guide

6.1 SMT Welding Instructions

This device is designed for reflow soldering processes. A key instruction is that the number of reflow process cycles must be less than two. Furthermore, if a second soldering is required, the device must be allowed to cool to normal ambient temperature between the first and second soldering processes. The recommended reflow profile includes a preheating stage at 120–150°C, with a maximum preheating time of 120 seconds. The peak temperature during reflow must not exceed 260°C. For manual soldering using a soldering iron, the maximum tip temperature is 300°C, and the soldering time per solder joint must not exceed 3 seconds.

6.2 Recommended Solder Pad Pattern

It provides pad pattern recommendations for PCB design. Adhering to this pattern is crucial for achieving reliable solder joints, proper alignment, and minimizing component stress during thermal cycling. This pattern defines the size, shape, and spacing of the copper pads on the PCB that correspond to the device terminals.

6.3 Moisture Sensitivity and Storage

SMD displays are shipped in moisture barrier packaging. They should be stored at 30°C or below, with a relative humidity of 60% or less. Once the original sealed package is opened, the components begin to absorb moisture from the atmosphere. If the parts are not stored in a controlled dry environment after opening, they must be baked before reflow soldering to prevent "popcorn" effect or internal delamination caused by rapid moisture expansion. Baking conditions are clearly specified: if still on reel, bake at 60°C for ≥48 hours; if in bulk, bake at 100°C for ≥4 hours or at 125°C for ≥2 hours. Baking can be performed only once.

7. Packaging and Ordering Information

The device is supplied in tape and reel form for automated pick-and-place assembly. Packaging reel and carrier tape dimensions are provided. The carrier tape material is specified as black conductive polystyrene alloy. The carrier tape dimensions comply with the EIA-481 standard. A standard 22-inch reel contains 38.5 meters of carrier tape and accommodates 1000 pieces. For the remainder of an order, the minimum packaging quantity is 250 pieces. The carrier tape includes leader and trailer tapes to facilitate machine feeding.

8. Application Design Considerations and Precautions

The datasheet contains important application notes. This display is suitable for general electronic equipment. For applications requiring extremely high reliability where failure could endanger life or health, consult the manufacturer before use. Designers must adhere to absolute maximum ratings. Exceeding recommended drive current or operating temperature may cause severe light output degradation or premature failure. The drive circuit should include protection against reverse voltage and transient voltage spikes during power-up or shutdown. Constant current drive is recommended over constant voltage drive to ensure consistent luminous intensity regardless of variations in forward voltage between individual LEDs or with temperature. Circuit design must consider the entire specified forward voltage range to ensure the intended drive current is always supplied. Proper heat dissipation and board layout should be considered to maintain junction temperature within safe limits, especially when operating at higher currents or in warm environments.

9. Technical Comparison and Differentiation

LTS-2806CKR-P achieves differentiation through its specific combination of attributes. Compared to older technologies like standard GaAsP, the red chip utilizing AlInGaP technology typically offers higher efficiency and better high-temperature performance. The 0.28-inch digit height fills a market gap between smaller, less visible displays and larger, more power-consuming ones. The common anode configuration is a key differentiating factor; many driver ICs are designed for common anode multiplexing, making this display compatible with a variety of standard display drivers. Its luminous intensity classification is a significant advantage for multi-digit designs compared to ungraded parts, ensuring visual consistency.

10. Frequently Asked Questions

Q: Can I drive this display with a 5V power supply and a simple resistor?
A: Yes, but careful calculation is required. Using a 5V power supply, with a typical forward voltage of 2.6V per segment, the voltage drop across the current-limiting resistor is 2.4V. For a desired current of 10 mA, the resistor value should be R = V/I = 2.4V / 0.01A = 240 Ω. However, you must use one resistor per segment cathode and consider the maximum forward voltage of 2.6V in your calculation to ensure the current never exceeds the maximum rating.

Q: Why is constant current drive recommended?
A: LED brightness is primarily a function of current, not voltage. The forward voltage has a negative temperature coefficient and can vary from device to device. A constant voltage source with a series resistor provides an approximate constant current, but it varies with changes in forward voltage. A dedicated constant current driver provides a stable current regardless of these variations, ensuring consistent brightness and longer lifespan.

Q: What does "1/10 duty cycle, 0.1ms pulse width" mean regarding the peak current rating?
A: This rating allows a brief high-current pulse for extra brightness in multiplexing or strobing effects. You can drive a segment with a 90 mA pulse, but the pulse itself must not exceed 0.1 ms in width, and the time-averaged current must adhere to the 1/10 duty cycle. In this scenario, the average current will be 9 mA, which must also remain within the continuous current derating limits for device temperature.

11. Design and Use Case Studies

Scenario: Designing a single-digit temperature readout display for a thermostat.LTS-2806CKR-P is an ideal choice. Designers selected a drive current of 5 mA per segment for battery-powered devices to balance brightness and power consumption. A microcontroller with integrated segment display drive pins was chosen. Since the display is common anode, the microcontroller's driver was configured accordingly. The PCB layout strictly followed the recommended solder pad pattern. After the reel was opened, the displays were stored in a dry cabinet. During assembly, a single reflow soldering process was used. The final product shows clear, uniformly bright red digits that are easy to read under typical indoor lighting conditions, and the low overall power consumption helps extend battery life.

12. Introduction to Technical Principles

The core light-emitting principle is based on a semiconductor PN junction. When a forward voltage is applied, electrons from the N-type material and holes from the P-type material are injected into the junction region. When an electron recombines with a hole, it falls to a lower energy state and releases the energy difference in the form of a photon. The specific wavelength of this light is determined by the bandgap of the semiconductor material. LTS-2806CKR-P uses AlInGaP, a compound semiconductor whose bandgap can be tuned by adjusting the proportions of its constituent elements to emit efficient light in the red to amber spectral region. The GaAs substrate provides a crystalline template for growing the AlInGaP epitaxial layer.

13. Industry Trends and Background

The trend for display components like the LTS-2806CKR-P is toward higher efficiency, smaller packages, and greater integration. While discrete segment displays remain crucial for specific applications, there is also a trend toward integrated dot-matrix displays and OLEDs, which offer greater flexibility in displaying characters and graphics. However, for simple, high-brightness, low-cost numeric indication, SMD segment displays using advanced semiconductor materials such as AlInGaP and InGaN are still widely used. The demand for lower power consumption, wider operating temperature ranges, and higher reliability drives innovation in materials and packaging. As shown by this component, the shift to lead-free and RoHS-compliant manufacturing is a standard industry requirement driven by environmental regulations.