LTS-4801JD LED Display Datasheet - 0.39-inch Digit Height - AlInGaP Hyper Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTS-4801JD is a high-performance, single-digit, seven-segment display module designed for applications requiring clear, bright numeric readouts. Its core function is to visually represent the digits 0-9 and some letters using individually addressable LED segments. The device is engineered for reliability and ease of integration into various electronic systems.

1.1 Core Advantages and Target Market

This display offers several key advantages that make it suitable for a range of applications. Its primary benefits include excellent character appearance with continuous uniform segments, high brightness and contrast for superior visibility even in well-lit conditions, and a wide viewing angle ensuring readability from various positions. Furthermore, it features low power requirement and solid-state reliability, contributing to long operational life and energy efficiency. The device is categorized for luminous intensity, providing consistency in brightness levels. The target market includes industrial control panels, test and measurement equipment, consumer appliances, automotive dashboards (secondary displays), and any embedded system requiring a compact, reliable numeric display.

2. Technical Specifications Deep Dive

The LTS-4801JD's performance is defined by a set of precise electrical and optical parameters that designers must consider for proper implementation.

2.1 Photometric and Optical Characteristics

The optical performance is central to its function. The device utilizes AlInGaP (Aluminum Indium Gallium Phosphide) Hyper Red LED chips. The light output is characterized by a typical average luminous intensity (Iv) of 200 to 650 microcandelas (μcd) when driven at a forward current (IF) of 1mA. The color is defined by a peak emission wavelength (λp) of 650 nanometers (nm) and a dominant wavelength (λd) of 639 nm, both measured at IF=20mA. The spectral line half-width (Δλ) is 20 nm, indicating a relatively pure red color. Luminous intensity matching between segments is specified at a ratio of 2:1 maximum, ensuring uniform appearance across the digit.

2.2 Electrical Parameters

Electrical specifications ensure safe and effective operation. The absolute maximum ratings define operational limits: power dissipation per segment is 70mW, peak forward current per segment is 90mA (at 1/10 duty cycle, 0.1ms pulse width), and continuous forward current per segment is 25mA at 25°C, derating linearly at 0.33 mA/°C. The maximum reverse voltage per segment is 5V. Under typical operating conditions (Ta=25°C, IF=20mA), the forward voltage per segment (VF) ranges from 2.1V to 2.6V. The reverse current (IR) is a maximum of 100 μA at VR=5V.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +85°C and an identical storage temperature range. This wide range makes it suitable for environments subject to significant temperature variations. The solder temperature rating specifies that the device can withstand 260°C for 3 seconds at a point 0.116 inches (or approximately 2.95mm) below the seating plane, which is critical information for the assembly process.

3. Binning System Explanation

The datasheet indicates the device is \"categorized for luminous intensity.\" This implies a binning system is applied, likely based on the measured average luminous intensity (Iv) at the standard test condition (IF=1mA). Bins would group devices with similar light output levels (e.g., 200-350 μcd, 350-500 μcd, 500-650 μcd). This allows designers to select parts with consistent brightness for multi-digit displays or applications where brightness matching is critical. The 2:1 maximum luminous intensity matching ratio specified is a performance guarantee within a single device, while binning ensures consistency across multiple devices.

4. Performance Curve Analysis

While the provided datasheet excerpt references \"Typical Electrical / Optical Characteristic Curves,\" typical curves for such a device would graphically illustrate key relationships vital for design.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

A typical I-V curve would show the exponential relationship between forward current (IF) and forward voltage (VF) for the AlInGaP LED chips. The curve would start conducting noticeably around 1.8V-2.0V and show a relatively steep slope in the normal operating range (e.g., 5-30mA), with VF increasing to the typical 2.1V-2.6V at 20mA. This curve is essential for designing the current-limiting circuitry.

4.2 Luminous Intensity vs. Forward Current

This curve is crucial for brightness control. It would typically show that luminous intensity (Iv) increases approximately linearly with forward current (IF) over a significant range before potentially saturating at very high currents. The slope of this line determines the efficiency (lumens per watt or candelas per ampere). Designers use this to select the operating current needed to achieve a desired brightness level.

4.3 Luminous Intensity vs. Ambient Temperature

LED light output decreases as junction temperature rises. A derating curve would illustrate the relative luminous intensity as a function of ambient temperature (Ta) or junction temperature (Tj). For AlInGaP LEDs, the output can drop significantly as temperature increases, which must be accounted for in thermal management and designs intended for high-temperature environments.

4.4 Spectral Distribution

A spectral power distribution graph would show the relative intensity of light emitted across different wavelengths, centered around the 650 nm peak. The 20 nm spectral half-width indicates the width of this peak at half its maximum intensity, confirming the monochromatic nature of the red light.

5. Mechanical and Packaging Information

The physical construction of the LTS-4801JD is defined for mechanical integration.

5.1 Dimensions and Outline Drawing

The package has a digit height of 0.39 inches (10.0 mm). The detailed dimensioned drawing (referenced in the datasheet) specifies the overall length, width, and height of the package, the segment dimensions and spacing, the lead (pin) spacing and length, and the position of the right-hand decimal point. All dimensions are in millimeters with a standard tolerance of ±0.25mm unless otherwise noted. This drawing is essential for creating the PCB footprint and ensuring proper fit within the enclosure.

5.2 Pinout and Polarity Identification

The device has a 10-pin configuration. It features a common anode architecture, meaning the anodes of all LED segments are connected internally and brought out to specific pins. The pin connection is as follows: Pin 3 and Pin 8 are Common Anodes (and are internally connected). The cathodes for each segment are on individual pins: Pin 1 (G), Pin 2 (F), Pin 4 (E), Pin 5 (D), Pin 6 (D.P. for decimal point), Pin 7 (C), Pin 9 (B), Pin 10 (A). Pin numbering and the location of pin 1 must be identified from the mechanical drawing. The \"Rt. Hand Decimal\" description confirms the decimal point is located on the right side of the digit.

5.3 Internal Circuit Diagram

The referenced internal circuit diagram visually represents the common anode configuration. It would show one common node (the anode) connected to the positive supply, with each segment's LED (A through G, plus DP) having its cathode connected to a separate pin. To illuminate a segment, its corresponding cathode pin must be driven low (connected to ground through a current-limiting resistor) while the common anode is held high.

6. Soldering and Assembly Guidelines

Proper handling is required to maintain device integrity.

6.1 Reflow Soldering Parameters

The critical parameter provided is the maximum solder temperature: 260°C for 3 seconds, measured 0.116 inches (2.95mm) below the seating plane. This aligns with typical lead-free reflow profiles (e.g., IPC/JEDEC J-STD-020). A standard reflow profile with a preheat zone, a rapid thermal ramp-up, a peak temperature zone not exceeding 260°C for the specified time, and a controlled cooling zone should be used. The profile must ensure the temperature at the package leads does not exceed the absolute maximum.

6.2 Precautions and Handling

Standard ESD (Electrostatic Discharge) precautions should be observed during handling and assembly, as LED chips are sensitive to static electricity. Avoid applying mechanical stress to the leads or the plastic package. Cleaning after soldering should use methods compatible with the package material (likely epoxy).

6.3 Storage Conditions

The device should be stored within the specified storage temperature range of -35°C to +85°C. It is advisable to store components in a low-humidity environment and in ESD-protective packaging until ready for use to prevent moisture absorption and electrostatic damage.

7. Application Recommendations

7.1 Typical Application Circuits

The most common drive method for a common anode display like the LTS-4801JD is multiplexing, especially when multiple digits are used. A microcontroller or dedicated display driver IC would sequentially power the common anode of each digit while outputting the cathode pattern for the segments that should be lit on that digit. This method saves I/O pins. For a single-digit application, a simpler static drive can be used: connect the common anode pins (3 & 8) to the positive supply voltage (Vcc) through a current-limiting resistor for the entire display, and connect each cathode pin (A-G, DP) to a microcontroller I/O pin or a driver transistor. Each I/O pin would need a series current-limiting resistor for its respective segment.

7.2 Current-Limiting Resistor Calculation

The value of the current-limiting resistor is critical. It can be calculated using Ohm's Law: R = (Vcc - VF) / IF. For example, with a Vcc of 5V, a typical VF of 2.6V, and a desired IF of 20mA: R = (5V - 2.6V) / 0.020A = 120 Ohms. The power rating of the resistor should be at least P = (IF)^2 * R = (0.020)^2 * 120 = 0.048W, so a standard 1/8W (0.125W) or 1/4W resistor is sufficient.

7.3 Design Considerations

Brightness Control: Brightness can be adjusted by varying the forward current (IF) within the specified limits, either by changing the resistor value or using PWM (Pulse Width Modulation) on the drive signal. PWM is highly effective for dimming.
Viewing Angle: The wide viewing angle is beneficial but consider the primary viewing direction when positioning the display in the final product.
Thermal Management: While power dissipation is low, ensure adequate ventilation if multiple displays are used or if operating at high ambient temperatures to prevent brightness degradation and extend lifespan.
Contrast Enhancement: The gray face and white segments provide inherent contrast. For optimal readability, a dark-colored bezel or filter around the display can further enhance contrast, especially in bright ambient light.

8. Technical Comparison and Differentiation

The LTS-4801JD differentiates itself primarily through its use of AlInGaP technology and specific performance characteristics.

AlInGaP vs. Other LED Technologies: Compared to traditional GaAsP or GaP red LEDs, AlInGaP LEDs offer significantly higher luminous efficiency (more light output per unit of electrical power), better temperature stability, and a more saturated, \"hyper\" red color. Compared to newer high-power white LEDs used with filters, this device is simpler, requires less complex drive electronics, and offers a pure, efficient red color directly.

Within Seven-Segment Displays: Its 0.39-inch digit height places it in a common size category for panel-mounted instruments. Key competitive advantages listed are its continuous uniform segments (for a clean appearance), high brightness and contrast, and categorization for luminous intensity (ensuring consistency). The low power requirement is also a benefit for battery-powered devices.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the purpose of having two common anode pins (Pin 3 and Pin 8)?
A1: Having two pins for the common connection helps distribute the total anode current, which is the sum of the currents of all illuminated segments. This reduces current density in a single pin and PCB trace, improving reliability. They are internally connected, so only one needs to be connected in a circuit, but connecting both is recommended for best performance.

Q2: Can I drive this display directly from a 3.3V microcontroller without a current-limiting resistor?
A2: No. You must always use a current-limiting resistor for each segment (or a regulated current source). The forward voltage (VF) is typically 2.1V-2.6V. Connecting 3.3V directly to the LED through a microcontroller pin would attempt to drive an uncontrolled, potentially destructive current through the LED, as the only resistance would be the internal resistance of the MCU pin and LED, which is very low.

Q3: What does \"derating linear from 25°C\" for continuous forward current mean?
A3: It means the maximum allowable continuous forward current decreases as the ambient temperature increases above 25°C. The derating factor is 0.33 mA/°C. For example, at 50°C (25°C above the reference), the maximum current would be 25mA - (0.33 mA/°C * 25°C) = 25mA - 8.25mA = 16.75mA. This prevents overheating and ensures reliability.

Q4: How do I interpret the luminous intensity matching ratio of 2:1?
A4: This means that within a single LTS-4801JD unit, the dimmest segment will be no less than half as bright as the brightest segment when measured under the same conditions (IF=1mA). This ensures visual uniformity across the digit.

10. Practical Design and Usage Case

Case: Designing a Simple Digital Voltmeter Readout
A designer is creating a compact digital voltmeter to display 0.0V to 19.9V. They need a clear, low-power display. They select the LTS-4801JD for its high brightness and 0.39-inch size, which is legible for the intended use. Three displays are used for the three digits. The microcontroller's ADC reads the voltage, converts it to a value, and drives the displays via a multiplexing scheme using a transistor array for the common anodes and the MCU's I/O pins (with series resistors) for the segment cathodes. The right-hand decimal point on the middle digit is used to show the tenths place. The AlInGaP red color is chosen for its high contrast against a dark panel. The designer calculates the resistor values for a 5V system to drive each segment at ~15mA, providing ample brightness while staying well within the 25mA continuous rating at room temperature.

11. Operating Principle Introduction

The LTS-4801JD operates on the fundamental principle of electroluminescence in semiconductor materials. The AlInGaP chip structure forms a p-n junction. When a forward voltage exceeding the junction's threshold (approximately 1.8-2.0V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region where they recombine. In AlInGaP, this recombination releases energy primarily in the form of photons (light) in the red wavelength range (~650 nm). Each of the seven segments (A through G) and the decimal point (DP) contains one or more of these tiny LED chips embedded in the package. The common anode configuration simplifies the external drive circuitry by allowing a single positive voltage source to power all segments, with individual control achieved by grounding the desired segment's cathode.

12. Technology Trends and Context

Seven-segment LED displays like the LTS-4801JD represent a mature and highly optimized display technology. While newer technologies like dot-matrix OLEDs or TFT LCDs offer greater flexibility (full graphics, multiple colors), seven-segment LEDs retain strong advantages in specific niches: extreme simplicity of drive electronics, very high brightness and contrast, excellent readability in direct sunlight, wide operating temperature range, and exceptional long-term reliability with no backlight to fail. The trend within this segment is towards higher efficiency (more lumens per watt) using advanced semiconductor materials like AlInGaP, as seen in this device, and towards surface-mount packages for automated assembly. They remain the go-to solution for applications where cost-effective, rugged, and highly legible numeric display is the primary requirement.