LTC-2621JD-04 LED Digital Tube Datasheet - 0.28-Inch Character Height - Super Bright Red (650nm) - 2.6V Forward Voltage - Technical Documentation

1. Product Overview

LTC-2621JD-04 na'urar nuni ce ta lambobi uku mai ƙarfi da ƙarfi, wacce aka tsara don aikace-aikacen da ke buƙatar karatun lambobi masu haske. Babban aikinta shine samar da fitarwa ta lambobi ta gani a cikin na'urorin lantarki. Babban fa'idar na'urar ita ce ta yi amfani da fasahar AlInGaP (aluminum indium gallium phosphide) na zamani don ƙirƙira guntu na LED, waɗanda aka yi akan tushen GaAs marar gani. Wannan haɗin yana haifar da siffa ta "ja mai haske sosai". Na'urar nuni tana amfani da zane na fuskar launin toka tare da sassan fararen lambobi, wanda ke ƙara bambanci da karantawa. Kasuwar da aka yi niyya ta haɗa da kayan aikin masana'antu, na'urorin lantarki na masu amfani, na'urorin gwaji da aunawa, da kowane tsarin da ke buƙatar nuni na lambobi mai aminci da ƙarancin wutar lantarki.

1.1 Key Features and Advantages

• Character Height:0.28 inches (7.0 mm), achieving a good balance between size and visibility.
• Segment Design:Continuous and uniform segment codes ensure excellent character appearance and aesthetics.
• Energy Efficiency:Low power consumption, suitable for battery-powered or energy-conscious applications.
• Optical Performance:High brightness and high contrast ensure good readability under various lighting conditions.
• Viewing Angle:Wide viewing angle allows reading the display content from off-axis positions.
• Reliability:Solid-state reliability, no moving parts, thus having a long service life.
• Quality Control:The devices are classified according to their luminous intensity to ensure brightness consistency across different production batches.

2. Detailed Technical Specifications

This section provides a detailed and objective analysis of the device's key technical parameters based on the datasheet.

2.1 Absolute Maximum Ratings

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

• Maximum Power Dissipation per Segment:Maximum 70 mW. This limits the maximum continuous power that a single segment can dissipate as heat.
• Peak forward current per segment:Maximum 90 mA, but only under specific pulse conditions: 1/10 duty cycle and 0.1 ms pulse width. This rating applies to multiplexing or short-duration high-brightness pulses.
• Continuous forward current per segment:Maximum 25 mA at 25°C. This current derates linearly at 0.33 mA/°C when the ambient temperature (Ta) exceeds 25°C. For example, at 85°C, the maximum allowable continuous current is approximately: 25 mA - ((85°C - 25°C) * 0.33 mA/°C) = 5.2 mA.
• Reverse voltage per segment:Maximum 5 V. Exceeding this value may cause junction breakdown.
• Operating temperature range:-35°C to +85°C. The device is designed to operate within this ambient temperature range.
• Storage temperature range:-35°C to +85°C.
• Soldering temperature:Maximum 260°C, up to 3 seconds, measured at a point 1.6 mm below the mounting plane. This is critical for wave soldering or reflow soldering processes to prevent thermal damage.

2.2 Electrical and Optical Characteristics (Ta=25°C)

These are typical operating parameters under specified test conditions.

• Average Luminous Intensity (I_V):The range is from 200 μcd (minimum) to 600 μcd (maximum), with a typical value implied. Measured at a forward current (I_F) of 1 mA. This is a key parameter for perceived brightness.
• Peak emission wavelength (λ_p):650 nm (typical). This is the wavelength at which the spectral output is strongest, defining the "super bright red" color.
• Spectral line half-width (Δλ):20 nm (typical value). This indicates spectral purity; a smaller value means the light is more monochromatic. 20nm is typical for AlInGaP red LEDs.
• Dominant wavelength (λ_d):639 nm (typical value). This is the single wavelength that matches the LED color as perceived by the human eye, usually slightly different from the peak wavelength.
• Forward voltage per segment (V_F):ranges from 2.1 V (minimum) to 2.6 V (maximum), with a typical value of 2.6 V at I_F=20 mA. This is crucial for designing current-limiting circuits.
• Reverse current per segment (I_R):at reverse voltage (V_RWhen the voltage is 5V, the maximum current is 100 μA.
• Luminous intensity matching ratio (I_V-m):Maximum 2:1. This specifies the maximum allowable ratio between the brightest and darkest segment/bit within the device, ensuring uniformity.

Measurement Description:Luminous intensity is measured using a sensor and filter approximating the CIE photopic response curve, ensuring the results correlate with human brightness perception.

3. Grading and Classification System

The datasheet explicitly states that devices are "classified according to luminous intensity." This implies the existence of a grading process.

• Luminous Intensity Binning:For I_VThe specified wide range (200-600 μcd) indicates that production parts are tested and sorted into different intensity bins. Designers can select a bin for applications requiring a specific brightness level or tight uniformity across multiple displays.
• Forward Voltage:The specified range (2.1-2.6V) may also lead to voltage grading, which could be important for power supply design in large arrays.
• Wavelength:Although typical values for λ_pand λ_dare given, tight tolerance grades for specific chromaticity coordinates may be available, though not detailed in this summary datasheet.

4. Performance Curve Analysis

The datasheet references "Typical Electrical/Optical Characteristic Curves." While specific graphs are not provided in the text, we can infer their standard content and importance.

• Relative Luminous Intensity vs. Forward Current (I-V Curve):This graph will show how the light output increases with current, typically in a sublinear relationship, highlighting the efficiency droop at high currents.
• Forward Voltage vs. Forward Current:Displaying the I-V characteristics of a diode is crucial for calculating series resistance values or designing constant current drivers.
• Relative Luminous Intensity vs. Ambient Temperature:It shows how light output decreases with increasing temperature, which is a key factor in thermal management.
• Spectral Distribution:A plot of relative intensity versus wavelength, showing a peak at approximately 650nm and a full width at half maximum of 20nm.

5. Mechanical and Packaging Information

5.1 Package Dimensions

This device uses a standard LED display package. All dimensions are in millimeters (mm). Unless otherwise specified for particular features, the general tolerance is ±0.25 mm (≈±0.01 inch). The exact dimensional drawing is referenced in the datasheet but not detailed here. Key aspects include overall length, width, height, digit spacing, pin pitch, and pin dimensions.

5.2 Pin Connections and Internal Circuitry

LTC-2621JD-04 is amultiplexed common anodedevice. This means that the anodes for each digit are internally connected together by digit, while the cathodes for each segment type (A-G, DP) are common across digits.

Pin Definitions (16-pin package):

• Pin 1: Cathode D
• Pin 2: Common Anode (Digit 1)
• Pin 3: Cathode D.P. (Decimal Point)
• Pin 4: Cathode E
• Pin 5: Common Anode (Digit 2)
• Pin 6: Cathode C
• Pin 7: Cathode G
• Pin 8: Common Anode (Digit 3)
• Pin 9: No Connection
• Pin 10: No pin
• Pin 11: No pin
• Pin 12: Cathode B
• Pin 13: Common anode for L1, L2, L3 (possibly a colon or other mark)
• Pin 14: No pin
• Pin 15: Cathode A
• Pin 16: Cathode F

Internal circuit diagram:The schematic shows three common anode nodes (one per digit) connected to pins 2, 5, and 8. Each segment cathode (A-G, DP) is a single node connected to its respective pin, with the LED for that segment in each digit connected between that digit's common anode and the shared segment cathode. This configuration is well-suited for multiplexed driving.

6. Soldering and Assembly Guide

The key guideline provided is the absolute maximum rating for soldering:Maximum 260°C, for up to 3 seconds, measured 1.6 mm below the seating plane.

• Reflow soldering:Standard lead-free reflow profile, peak temperature not exceeding 260°C, with a very short time above 240°C, should be compatible. The 1.6 mm measurement point is critical for profile verification.
• Wave soldering:Feasible, but contact time and temperature must be carefully controlled to meet the 260°C/3 seconds limit.
• Hand soldering:Use a temperature-controlled soldering iron. Apply heat to the PCB pad, not directly to the LED leads, and complete the soldering quickly.
• Storage Conditions:Within the specified storage temperature range (-35°C to +85°C), store in a dry, anti-static environment. If exposed to a humid environment, moisture-sensitive devices may require baking before use.

7. Application Suggestions

7.1 Typical Application Circuit

Multiplexed common anode configuration requires a driving circuit. Typical design uses:

• Microcontroller or driver IC:For controlling timing and data.
• Bit drive:PNP transistor or dedicated high-side switch for sinking current into the common anode pins (2, 5, 8, 13).
• Segment drive:Microcontroller port or low-side drive IC (such as a 74HC595 shift register with open-drain output or a dedicated LED driver), used to sink current from the segment cathode pins (1, 3, 4, 6, 7, 12, 15, 16).
• Current Limiting Resistor:When using constant voltage drive, a resistor is required for each segment cathode line (not for each segment LED). The resistor value is calculated using R = (V_{Power supply}- V_F) / I_FCalculation. For a 5V power supply, I_F=10 mA, V_F=2.6V, R = (5 - 2.6) / 0.01 = 240 Ω. For better uniformity, a constant current driver is preferred.

7.2 Design Considerations

• Multiplexing Frequency:使用足够高的刷新率以避免可见闪烁（通常每位>60 Hz，因此3位扫描速率>180 Hz）。
• Peak Current vs. Brightness:To achieve high average brightness while maintaining the continuous current rating, use multiplexing with a higher peak current (up to 90mA pulse rating). For example, driving at a 1/3 duty cycle (3 digits) with a 30mA peak results in an average current of 10mA per segment.
• Thermal Management:Ensure PCB layout allows for heat dissipation, especially when driving close to the maximum rated values. High ambient temperatures will require current derating.
• ESD Protection:LED yana da hankali ga zubar da tashin hankali. Yi amfani da matakan rigakafin ESD masu dacewa yayin haɗawa.

8. Technical Comparison and Differentiation

Idan aka kwatanta da tsofaffin fasahohi kamar LED ja na GaP na yau da kullun ko manyan na'urorin nuni na lambobi, LTC-2621JD-04 yana ba da fa'idodi na musamman:

• AlInGaP vs. GaAsP/GaP:AlInGaP technology offers significantly higher luminous efficiency, resulting in higher brightness and better visibility under ambient light. The "super bright red" color is also more vivid.
• Small character height (0.28 inches):Gray panel/white segment:
• When the segment codes are off, this surface treatment provides high contrast, improving overall display aesthetics and readability compared to all-black or all-gray panels.Intensity Grading:
• This grading provides a degree of quality control and predictability, which is not always present in low-cost displays.9. Frequently Asked Questions (Based on Technical Parameters)

Q1: What is the purpose of the "common anode" configuration?

A1: Common anode simplifies multiplexing. You light one digit at a time by applying a positive voltage to its anode pin while grounding the cathodes of the segments you want to illuminate. This reduces the required drive pins from (7 segments + 1 DP) * 3 digits = 24 to 3 anodes + 8 cathodes = 11.
Q2: How do I calculate the resistor values for driving this display?

A2: Use Ohm's Law: R = (V
Power supply_{- V}) / I_F. Use the maximum V from the datasheet_F(2.6V) to ensure sufficient voltage drop across the resistor even for high V_Fparts. Select I based on the required brightness_F, staying within the continuous (25mA at 25°C) or pulsed ratings._FQ3: Can I drive this display with a 3.3V microcontroller?

A3: Possibly, but with limitations. If V
is 2.6V, then at 3.3V, only 0.7V of voltage drop remains across the current-limiting resistor. For a 10mA current, R=70Ω. This low resistance value is feasible, but V_Fvariation will cause significant brightness changes. For stable performance, it is recommended to use a constant current driver or a boost converter to provide a higher supply voltage (e.g., 5V)._FQ4: "Luminous intensity matching ratio 2:1" yana nufin me?

A4: Wannan yana nufin cewa a cikin naúrar LTC-2621JD-04 guda, a ƙarƙashin yanayi iri ɗaya (I
=1mA) lokacin aunawa, hasken sashe ko lamba mafi haske ba zai wuce sau biyu na hasken sashe ko lamba mafi duhu ba. Wannan yana tabbatar da daidaiton gani._F10. Zane da Nazarin Lamarin Amfani

Scenario: Designing a Portable Digital Multimeter Display

LTC-2621JD-04 is an excellent choice. Its 0.28-inch digit height is highly legible. Low power requirements are crucial for battery life. The multiplexed design minimizes the number of microcontroller pins. The design will use the microcontroller's timer to cycle through digits 1, 2, and 3 at approximately 200 Hz. Segment data will be fetched from a lookup table. To save power, the display brightness (I
) can be dynamically adjusted based on ambient light sensed by a phototransistor. The high-contrast gray/white panel ensures readability in both dark and bright workshop environments. The AlInGaP ultra-bright red LED provides a clear, compelling readout._F11. Introduction to Technical Principles

LTC-2621JD-04 based

AlInGaP (aluminum indium gallium phosphide)semiconductor material, which is epitaxially grown onGaAs (gallium arsenide)On the substrate. The "opaque" GaAs substrate is used because it absorbs the emitted light, but the AlInGaP active layer has a sufficiently high internal efficiency, allowing enough light to escape from the top of the chip. When a forward voltage is applied across the p-n junction, electrons and holes are injected into the active region. Their recombination releases energy in the form of photons. The specific composition of the AlInGaP alloy determines the bandgap energy, which directly defines the wavelength (color) of the emitted light—in this case, approximately 650 nm (red). The seven-segment format is formed by placing multiple micro-LED chips (or a single chip with multiple isolated junctions) under a patterned optical lens/diffuser to create recognizable digit segments.12. Technical Trends and Background

Although this specific device uses through-hole technology, the underlying AlInGaP material system remains highly relevant. Trends in display technology include:

Miniaturization:

• Development towards Surface Mount Device (SMD) packaging to enable automated assembly, even for multi-digit displays.Integration:
• Combining LED arrays with driver ICs in a single package or module to simplify design.Advanced Materials:
• Ongoing research on materials like GaN (for blue/green/white) and AlInGaP to improve efficiency and develop new colors. For red/orange/yellow light, AlInGaP is the dominant high-performance technology.Application Shift:
• Although discrete seven-segment displays are a mature technology, they remain crucial in applications where simplicity, cost, reliability, and high visibility are paramount (industrial control, home appliances, instrumentation). They coexist with newer technologies like OLED and LCD, each serving different market segments based on factors such as viewing angle, sunlight readability, power consumption, and cost.The LTC-2621JD-04 represents a robust, well-established solution within this evolving landscape, offering a proven balance of performance, reliability, and cost for its intended applications.

The LTC-2621JD-04 represents a robust, well-established solution within this evolving landscape, offering a proven balance of performance, reliability, and cost for its intended applications.