LTC-2621JD-01 LED Display Datasheet - 0.28-inch Digit Height - Hyper Red 650nm - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTC-2621JD-01 is a compact, high-performance triple-digit numeric display module. It is designed for applications requiring clear, bright numeric readouts in a small form factor. The core technology utilizes AlGaInP (Aluminum Gallium Indium Phosphide) semiconductor material to produce a Hyper Red emission, offering superior brightness and efficiency compared to traditional red LEDs. The device features a gray face and white segment color for high contrast and excellent readability under various lighting conditions.

1.1 Core Advantages

• High Visibility: 0.28-inch (7 mm) digit height with continuous uniform segments ensures clear character definition.
• Optical Performance: High brightness and high contrast ratio are achieved through the AlGaInP Hyper Red LED chips.
• Wide Viewing Angle: Provides consistent luminosity and color across a broad viewing range.
• Low Power Consumption: Efficient design requires minimal drive current for operation.
• Reliability: Solid-state construction ensures long operational life and resistance to shock and vibration.
• Standardization: Devices are categorized (binned) for luminous intensity, allowing for consistent brightness matching in multi-unit applications.
• Environmental Compliance: The package is lead-free and compliant with RoHS directives.

1.2 Target Applications

This display is suitable for a wide range of electronic equipment requiring numeric indication. Typical applications include instrumentation panels, test and measurement equipment, point-of-sale terminals, industrial controllers, and consumer appliances. Its reliability makes it appropriate for general-purpose use where clear numeric data presentation is essential.

2. Technical Specifications and Objective Interpretation

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation under or at these limits is not guaranteed.

• Power Dissipation per Segment: 70 mW. This limits the combined effect of forward current and voltage drop across a segment.
• Peak Forward Current per Segment: 90 mA (at 1/10 duty cycle, 0.1ms pulse width). For pulsed operation only, not for DC.
• Continuous Forward Current per Segment: 25 mA at 25°C, derating linearly at 0.28 mA/°C above 25°C. This is the key parameter for DC or average current design.
• Reverse Voltage per Segment: 5 V. Exceeding this can cause immediate and catastrophic failure.
• Operating & Storage Temperature Range: -35°C to +105°C. The device is rated for industrial temperature ranges.

2.2 Electrical & Optical Characteristics

These are typical operating parameters measured at Ta=25°C, defining the expected performance under normal conditions.

• Average Luminous Intensity (I_V): 320 to 850 µcd at I_F=1mA. This wide range indicates the device is available in different brightness bins (see section 2.3).
• Peak Emission Wavelength (λ_p): 650 nm (Hyper Red).
• Dominant Wavelength (λ_d): 636 nm. This is the wavelength perceived by the human eye.
• Forward Voltage per Segment (V_F): 2.1V to 2.6V at I_F=20mA. Circuit design must accommodate this range to ensure proper current regulation.
• Reverse Current per Segment (I_R): 100 µA maximum at V_R=5V.

2.3 Binning System Explanation

The luminous intensity is categorized into bins to ensure consistency. The bin table provided shows grades F through K, with intensity ranges from 321-500 µcd (F) up to 2101-3400 µcd (K) when measured at a higher drive current of 10mA. A tolerance of ±15% applies within each bin. For applications using multiple displays side-by-side, specifying the same bin grade is strongly recommended to avoid noticeable differences in brightness (hue unevenness).

3. Mechanical and Package Information

3.1 Package Dimensions

The display conforms to a standard dual in-line package (DIP) footprint. Key dimensional notes include: all primary dimensions are in millimeters with a general tolerance of ±0.25 mm, and the pin tip shift tolerance is +0.4 mm. Designers should refer to the detailed dimensioned drawing on page 3 of the datasheet for exact measurements for PCB layout, including seating plane, overall height, width, and pin spacing.

3.2 Pin Configuration and Internal Circuit

The device has a 16-pin configuration, though not all positions are populated (pins 10, 11, 14 are \"NO PIN\"). It is a multiplexed common anode display. The internal circuit diagram shows three common anode pins (for Digit 1, Digit 2, Digit 3) and separate cathode pins for each segment (A-G, DP) and colon segments (L1, L2, L3). Pin 13 serves as the common anode for the colon points. This structure requires a multiplexed driving scheme where anodes are energized sequentially while the corresponding segment cathodes are pulled low.

4. Application Guidelines and Design Considerations

4.1 Driving Circuit Design

• Current Drive: Constant current driving is strongly recommended over constant voltage to ensure consistent luminous intensity and longevity, as the forward voltage (V_F) has a range.
• Current Limiting: The circuit must be designed to never exceed the absolute maximum continuous current, considering ambient temperature derating.
• Reverse Voltage Protection: The driving circuit should incorporate protection (e.g., series resistors, clamping diodes) to prevent reverse voltage or voltage spikes from being applied to the LED segments during power cycling.
• Multiplexing: A suitable multiplexing frequency (typically >100Hz) must be used to avoid visible flicker. The peak current in a multiplexed scheme can be higher than the average DC current but must stay within the peak current rating.

4.2 Thermal and Environmental Management

• Heat Dissipation: Exceeding the recommended operating current or ambient temperature will accelerate light output degradation and can lead to premature failure. Adequate PCB copper area or other heatsinking may be necessary in high-temperature environments.
• Condensation: Rapid temperature changes in humid environments should be avoided, as condensation on the display surface can cause optical issues or electrical leakage.
• Mechanical Stress: No abnormal force should be applied to the display body during assembly. Suitable tools must be used.

4.3 Storage and Handling

For long-term storage of the LED display in its original packaging, conditions of 5°C to 30°C and below 60% RH are recommended. If stored outside a moisture barrier bag or if the bag has been open for more than six months, it is advised to bake the components at 60°C for 48 hours before use and to complete assembly within one week to prevent oxidation of the pins and ensure solderability.

5. Soldering and Assembly Guide

The datasheet specifies solder conditions: the component should be subjected to 260°C for 3 seconds, measured 1/16 inch (approximately 1.6 mm) below the seating plane. This is a typical reflow soldering profile reference. The temperature of the component body itself must not exceed the maximum storage temperature of 105°C during the assembly process. Standard reflow profiles for lead-free soldering can be used with careful thermal profiling to meet these criteria.

6. Performance Curves and Analysis

The datasheet references typical performance curves which would normally include:

• Relative Luminous Intensity vs. Forward Current: Shows the non-linear relationship between drive current and light output.
• Forward Voltage vs. Forward Current: Illustrates the diode characteristic curve.
• Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as junction temperature rises.
• Spectral Distribution: A graph showing the intensity of emitted light across wavelengths, centered around 650nm.

These curves are crucial for designers to optimize the drive conditions for a specific brightness requirement while maintaining efficiency and reliability over the intended operating temperature range.

7. Technical Comparison and Differentiation

The primary differentiator of the LTC-2621JD-01 is its use of AlGaInP Hyper Red technology. Compared to older GaAsP or standard red GaP LEDs, AlGaInP offers significantly higher luminous efficiency, resulting in greater brightness for the same drive current, or equivalent brightness at lower power. The \"Hyper Red\" designation indicates a deeper, more saturated red color (650nm peak) compared to standard red LEDs, which often have a dominant wavelength around 630-635nm. The 0.28-inch digit height provides a balance between readability and board space economy.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display with a 5V microcontroller pin directly?
A: No. The forward voltage is only 2.1-2.6V. Driving it directly with 5V would cause excessive current and destroy the segment. A current-limiting resistor or, preferably, a constant current driver circuit is required.

Q: What is the difference between Peak Wavelength (650nm) and Dominant Wavelength (636nm)?
A: Peak wavelength is where the spectral output is physically strongest. Dominant wavelength is the single-wavelength color that would be perceived as matching the LED's color by the human eye, which is influenced by the entire spectral curve. Both are standard specifications.

Q: Why is binning important?
A: The manufacturing process creates natural variations in brightness. Binning sorts LEDs into groups with similar performance. Using displays from the same bin in a multi-unit application ensures uniform appearance.

Q: How do I calculate the required current-limiting resistor?
A: Use Ohm's Law: R = (V_supply - V_F) / I_F. Use the maximum V_F (2.6V) from the datasheet to ensure enough voltage is available to achieve the desired I_F under all conditions. For example, with a 5V supply and target I_F of 20mA: R = (5V - 2.6V) / 0.020A = 120 Ω. Always verify power dissipation in the resistor as well.

9. Design and Usage Case Example

Scenario: Designing a simple 3-digit voltmeter display for a benchtop power supply.
Implementation: A microcontroller with sufficient I/O pins would be used. Three pins would be configured as digital outputs to drive the digit anodes (pins 2, 5, 8) via small NPN transistors or MOSFETs. Seven or eight other pins would drive the segment cathodes (pins 1, 3, 4, 6, 7, 12, 15, 16) through current-limiting resistors or a dedicated LED driver IC capable of constant current sink outputs. The microcontroller firmware would implement multiplexing: turn on the transistor for Digit 1, set the cathode pattern for the desired number on Digit 1, wait a short time (e.g., 2ms), turn off Digit 1, and repeat for Digits 2 and 3. This cycle would run continuously. The brightness can be adjusted by varying the value of the current-limiting resistors or the duty cycle of the multiplexing.

10. Operating Principle Introduction

An LED (Light Emitting Diode) is a semiconductor p-n junction diode. When a forward voltage exceeding the diode's threshold is applied, electrons from the n-type material recombine with holes from the p-type material in the depletion region. This recombination releases energy in the form of photons (light). The specific wavelength (color) of the light is determined by the energy bandgap of the semiconductor material used. AlGaInP has a bandgap corresponding to red/orange/amber light. In this multiplexed display, individual segments are LEDs. By selectively powering the common anode of a digit and grounding the cathodes of specific segments, those segments light up to form a numeral.

11. Technology Trends

The trend in display technologies like this is towards higher efficiency, lower power consumption, and increased integration. While discrete LED digit displays remain popular for their simplicity, brightness, and wide viewing angle, they are increasingly complemented or replaced in some applications by more integrated solutions like OLED (Organic LED) displays or TFT-LCDs, which offer graphical capabilities. However, for applications requiring extremely bright, rugged, and simple numeric readouts, especially in industrial or outdoor settings, LED digit displays like the LTC-2621JD-01 continue to be a reliable and cost-effective choice. Future developments may see even higher efficiency materials and perhaps integrated driver circuitry within the display package itself.