LTC-2623JD-01 LED Display Datasheet - 0.28-inch Digit Height - Hyper Red - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTC-2623JD-01 is a quadruple-digit, seven-segment LED display module designed for applications requiring clear numeric readouts with minimal power consumption. Its primary function is to provide a highly legible, multi-digit numeric display using solid-state LED technology. The core advantage of this device lies in its utilization of AlInGaP (Aluminum Indium Gallium Phosphide) Hyper Red LED chips, which offer superior luminous efficiency and color purity compared to traditional materials. This results in excellent character appearance, high brightness, and high contrast even at low drive currents. The device is categorized for luminous intensity, ensuring consistent brightness levels across units, and is packaged in a lead-free format compliant with environmental regulations.

1.1 Key Features

• Digit Height: 0.28 inches (7.0 mm).
• Continuous Uniform Segments for smooth character appearance.
• Low Power Requirement, capable of operation at drive currents as low as 1mA per segment.
• Excellent Characters Appearance due to the AlInGaP technology and gray face with white segments.
• High Brightness & High Contrast.
• Wide Viewing Angle.
• Solid State Reliability.
• Categorized for Luminous Intensity (Binning).
• Lead-Free Package (RoHS compliant).

1.2 Device Identification

The part number LTC-2623JD-01 specifies a multiplex common anode display with AlInGaP Hyper Red LEDs and a right-hand decimal point.

2. Technical Parameters Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation should always be maintained within these limits.

• Power Dissipation per Segment: 70 mW.
• Peak Forward Current per Segment: 90 mA (at 1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA (at 25°C). This rating derates linearly above 25°C at a rate of 0.28 mA/°C.
• Reverse Voltage per Segment: 5 V.
• Operating Temperature Range: -35°C to +105°C.
• Storage Temperature Range: -35°C to +105°C.
• Solder Conditions: 260°C for 3 seconds, 1/16 inch (approx. 1.6 mm) below the seating plane.

2.2 Electrical & Optical Characteristics

These are the typical performance parameters measured at an ambient temperature (Ta) of 25°C.

• Average Luminous Intensity (Iv): 320 (Min), 850 (Typ) µcd at a forward current (IF) of 1mA. This exceptionally low test current highlights the device's efficiency.
• Peak Emission Wavelength (λp): 650 nm (Typ) at IF=20mA, placing it in the Hyper Red spectrum.
• Spectral Line Half-Width (Δλ): 20 nm (Typ) at IF=20mA.
• Dominant Wavelength (λd): 636 nm (Typ) at IF=20mA.
• Forward Voltage per Segment (VF): 2.1 (Min), 2.6 (Typ) V at IF=20mA.
• Reverse Current per Segment (IR): 100 µA (Max) at a reverse voltage (VR) of 5V.
• Luminous Intensity Matching Ratio: 2:1 (Max) between segments under similar conditions (IF=1mA).

3. Binning System Explanation

The device employs a binning system for luminous intensity to ensure consistency in applications using multiple displays. The bin grade is defined at a forward current of 10mA.

• Bin F: 321 - 500 µcd
• Bin G: 501 - 800 µcd
• Bin H: 801 - 1300 µcd
• Bin J: 1301 - 2100 µcd
• Bin K: 2101 - 3400 µcd

The luminous intensity tolerance within a specific bin is ±15%. For multi-unit assemblies, it is strongly recommended to use displays from the same bin grade to avoid noticeable differences in brightness (hue unevenness).

4. Performance Curve Analysis

While specific graphical curves are referenced in the datasheet, their implications are critical for design.

• IV (Current-Voltage) Curve: Understanding this relationship is essential for designing the current-limiting circuitry. The forward voltage has a typical value of 2.6V at 20mA but will vary with temperature and between individual LEDs.
• Luminous Intensity vs. Forward Current: The light output is not linearly proportional to current, especially at higher currents where efficiency may drop due to heating.
• Temperature Characteristics: The forward voltage (VF) typically decreases with increasing junction temperature, while luminous efficiency also degrades at high temperatures. The derating of continuous forward current (0.28 mA/°C above 25°C) is a direct result of thermal management requirements.

5. Mechanical & Package Information

5.1 Package Dimensions

The display follows a standard dual in-line package (DIP) footprint. Key dimensional notes include:

• All primary dimensions are in millimeters.
• General tolerance is ±0.25 mm unless otherwise specified.
• Pin tip shift tolerance is +0.4 mm, which is important for wave soldering or socket insertion.

5.2 Pin Connection and Internal Circuit

The device has a multiplex common anode configuration. This means the anodes of the LEDs for each digit are connected together internally, while the cathodes for each segment type (A-G, DP) are connected across digits. This reduces the required number of control lines. The pinout is as follows: Pin 1 (Common Anode Digit 1), Pin 2 (Cathode C, L3), Pin 3 (Cathode DP), Pin 4 (No Connection), Pin 5 (Cathode E), Pin 6 (Cathode D), Pin 7 (Cathode G), Pin 8 (Common Anode Digit 4), Pin 9 (No Connection), Pin 10 (No Pin), Pin 11 (Common Anode Digit 3), Pin 12 (Common Anode for L1, L2, L3), Pin 13 (Cathode A, L1), Pin 14 (Common Anode Digit 2), Pin 15 (Cathode B, L2), Pin 16 (Cathode F). An internal circuit diagram would show the common anode nodes for digits 1-4 and the shared cathode lines for each segment across these digits.

6. Soldering, Assembly & Storage Guidelines

6.1 Soldering

The recommended soldering condition is 260°C for 3 seconds, measured 1.6mm below the seating plane. This is a typical reflow or wave soldering profile. Exceeding this temperature or duration can damage the internal wire bonds or the LED chips themselves.

6.2 Storage Conditions

To prevent pin oxidation and maintain performance, the display should be stored in its original moisture-barrier packaging under the following conditions:

• Temperature: 5°C to 30°C.
• Relative Humidity: Below 60% RH.

If these conditions are not met, pin oxidation may occur, requiring re-plating before use. It is advised to consume inventory promptly and avoid long-term storage of large quantities.

7. Application Notes & Design Considerations

7.1 Driving Circuit Design

• Constant Current Drive: Highly recommended over constant voltage drive to ensure consistent luminous intensity across segments and over temperature variations.
• Current Limiting: The circuit must be designed to limit the current to each segment to a safe level, considering the maximum ambient temperature and using the derating factor.
• Forward Voltage Range: The power supply must accommodate the full range of VF (min 2.1V, typ 2.6V) to ensure the intended drive current is always delivered.
• Reverse Voltage Protection: The driving circuit should incorporate protection (e.g., diodes in series or parallel) to prevent reverse bias or transient voltage spikes during power cycling, which can cause metal migration and failure.
• Multiplexing: As a common anode multiplexed display, it requires a driver IC or microcontroller capable of sequentially energizing each digit's common anode while presenting the correct cathode pattern for that digit's segments. The persistence of vision creates the illusion of all digits being on simultaneously.

7.2 Mechanical and Environmental Considerations

• Condensation: Avoid rapid temperature changes in humid environments to prevent condensation on the display surface, which could cause electrical issues.
• Mechanical Stress: Do not apply abnormal force to the display body during assembly. Use appropriate tools.
• Filter/Overlay Attachment: If using a pressure-sensitive adhesive film (pattern film), ensure it does not make tight contact with a front panel, as external force may shift it.
• Vibration/Drop Testing: If the end product requires such testing, the conditions should be evaluated in advance to ensure display compatibility.

8. Typical Application Scenarios

This display is suited for ordinary electronic equipment where clear, low-power numeric indication is needed. This includes, but is not limited to:

• Test and measurement equipment (multimeters, power supplies).
• Industrial control panels and timers.
• Consumer appliances (microwaves, ovens, washing machines).
• Point-of-sale terminals and calculators.
• Medical monitoring devices (where exceptional reliability is not the primary safety factor; for critical life-support applications, consultation with the manufacturer is mandatory).

9. Technical Comparison & Differentiation

The LTC-2623JD-01 differentiates itself primarily through its AlInGaP Hyper Red LED technology. Compared to older GaAsP or standard red GaP LEDs, AlInGaP offers:

• Higher Luminous Efficiency: More light output (lumens) per unit of electrical input power (watts), enabling bright displays at very low currents like 1mA.
• Superior Color Purity: The dominant wavelength of 636nm provides a deep, saturated red color.
• Better Temperature Stability: Generally exhibits less efficiency drop with increasing temperature than older technologies.
• The combination of low current capability, high brightness, and binning for intensity consistency makes it a strong choice for battery-powered or efficiency-conscious designs requiring a multi-digit red display.

10. Frequently Asked Questions (FAQ)

10.1 What is the minimum current needed to light a segment?

The datasheet specifies a test condition of 1mA for luminous intensity, indicating it is designed to operate effectively at this very low current. The actual minimum visible current will be lower, depending on ambient light.

10.2 Why is constant current drive recommended?

LED brightness is primarily a function of current, not voltage. The forward voltage (VF) varies with temperature and between individual LEDs. A constant current source ensures that the light output remains stable despite these variations, providing uniform brightness across all segments and over the operating temperature range.

10.3 Can I drive it directly from a microcontroller pin?

No, not directly for all segments simultaneously. A typical MCU pin can source or sink only 20-40mA. This display requires up to 25mA per segment and uses multiplexing. You need external drivers (e.g., transistor arrays or dedicated LED driver ICs) to handle the current and multiplexing logic.

10.4 What does \"Categorized for Luminous Intensity\" mean?

It means the displays are tested and sorted into brightness groups (Bins F through K). This allows designers to select displays with similar brightness for multi-unit applications, preventing some digits from appearing brighter or dimmer than others.

11. Design-in Case Study Example

Scenario: Designing a portable, battery-operated environmental data logger that displays temperature and humidity readings on a 4-digit display.

Design Choices using LTC-2623JD-01:

1. Power Efficiency: The ability to drive segments at 1-5mA significantly extends battery life compared to displays requiring 10-20mA.
2. Driver Selection: A low-power, multiplexing LED driver IC with constant current outputs is selected. The driver's current is set to 3mA per segment, providing good visibility while staying well within the 25mA limit.
3. Binning: For production, displays from Bin G (501-800 µcd @10mA) are specified to ensure all units have consistent, mid-range brightness.
4. Circuit Protection: Schottky diodes are placed in series with each common anode line to protect against accidental reverse polarity connection of the battery.
5. Thermal Management: The device is housed in a plastic enclosure. The maximum ambient temperature is estimated at 50°C. Using the derating factor (0.28 mA/°C above 25°C), the maximum safe continuous current per segment at 50°C is: 25 mA - [0.28 mA/°C * (50°C - 25°C)] = 25 mA - 7 mA = 18 mA. The chosen 3mA drive current provides a large safety margin.

12. Operating Principle

The display is based on the electroluminescence principle of semiconductor LEDs. When a forward bias voltage exceeding the diode's bandgap voltage is applied across the AlInGaP p-n junction, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of the AlInGaP semiconductor determines the wavelength (color) of the emitted light, in this case, hyper red (~636nm). The seven segments are individual LEDs arranged in a figure-eight pattern. By selectively powering different combinations of these segments, the numerals 0-9 and some letters can be formed. The multiplexed common anode architecture reduces the number of required I/O pins from (7 segments + 1 DP) * 4 digits = 32 to 4 common anodes + 8 shared cathodes = 12 control lines, plus power.

13. Technology Trends

While seven-segment displays remain fundamental, the underlying LED technology continues to evolve. AlInGaP represents an advanced material system for red and amber LEDs. Current trends influencing such displays include:

• Increased Efficiency: Ongoing research aims to improve the internal quantum efficiency and light extraction of AlInGaP LEDs, potentially allowing even lower operating currents or higher brightness.
• Miniaturization: There is a trend towards smaller pixel pitches and higher-density multi-digit modules, though the 0.28-inch size remains a standard for legibility.
• Integration: Some modern displays integrate the driver IC directly into the package, simplifying the external circuit design.
• Alternative Technologies: For full-color or graphical needs, OLED (Organic LED) dot-matrix displays are becoming more common, but for simple, high-brightness, low-power numeric readouts, LED seven-segment displays like the LTC-2623JD-01, especially with efficient materials like AlInGaP, maintain a strong position due to their reliability, simplicity, and cost-effectiveness.