LTC-4627JD-01 LED Display Datasheet - 0.4-inch Digit Height - Hyper Red - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTC-4627JD-01 is a quadruple-digit, seven-segment LED display designed for numeric readout applications. Each digit features a height of 0.4 inches (10.0 mm), providing clear and legible characters suitable for a variety of electronic equipment interfaces. The device utilizes AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology to produce a Hyper Red emission. It features a gray face with white segments, enhancing contrast and readability. The display is constructed as a multiplex common anode type, which is a standard configuration for multi-digit displays to minimize the number of required driver pins.

1.1 Key Features

• Digit Height: 0.4 inch (10.0 mm).
• Segment Design: Continuous uniform segments for consistent character appearance.
• Power Efficiency: Low power requirement.
• Optical Performance: Excellent character appearance, high brightness, and high contrast.
• Viewing Angle: Wide viewing angle.
• Reliability: Solid-state reliability.
• Quality Control: Categorized for luminous intensity (binned).
• Environmental Compliance: Lead-free package compliant with RoHS directives.

1.2 Device Identification

The part number LTC-4627JD-01 specifically denotes a multiplex common anode display with AlInGaP Hyper Red LEDs and includes a right-hand decimal point.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

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

• 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), derating linearly by 0.28 mA/°C above 25°C.
• Operating Temperature Range: -35°C to +105°C
• Storage Temperature Range: -35°C to +105°C
• Soldering Condition: Wave soldering at 260°C for 3 seconds, with the solder point at least 1/16 inch (approx. 1.6 mm) below the seating plane of the display body.

2.2 Electrical & Optical Characteristics

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

• Average Luminous Intensity (I_V): 200 - 650 μcd (at I_F = 1 mA). This is the primary measure of brightness.
• Peak Emission Wavelength (λ_p): 650 nm (at I_F = 20 mA). This is the wavelength at which the emitted light intensity is highest.
• Spectral Line Half-Width (Δλ): 20 nm (at I_F = 20 mA). This indicates the color purity; a smaller value means a more monochromatic light.
• Dominant Wavelength (λ_d): 639 nm (at I_F = 20 mA). This is the wavelength perceived by the human eye.
• Forward Voltage per Chip (V_F): 2.1 V (Min), 2.6 V (Typ) (at I_F = 20 mA). Tolerance is ±0.1V.
• Reverse Current per Segment (I_R): 100 μA Max (at V_R = 5V). Note: This is a test condition; continuous reverse bias operation is not permitted.
• Luminous Intensity Matching Ratio: 2:1 Max (for segments within the same light area, at I_F = 1 mA). This ensures uniformity in brightness across segments.
• Cross Talk: ≤ 2.5%. This specifies the maximum allowable light leakage between adjacent segments when one is on and the other is off.

2.3 Binning System for Luminous Intensity

The LEDs are sorted (binned) based on their luminous intensity measured at a forward current of 10 mA. This allows designers to select displays with consistent brightness levels for their application. The binning table is as follows:

• Bin E: 200 - 320 μcd
• Bin F: 321 - 500 μcd
• Bin G: 501 - 800 μcd
• Bin H: 801 - 1300 μcd
• Bin J: 1301 - 2100 μcd

The luminous intensity tolerance within a selected bin is ±15%. For applications using multiple displays in one assembly, it is strongly recommended to use displays from the same bin to avoid noticeable differences in brightness (hue unevenness).

3. Mechanical & Package Information

3.1 Package Dimensions

The display conforms to a standard dual in-line package (DIP) footprint. All dimensions are in millimeters with a general tolerance of ±0.25 mm unless otherwise specified. Key mechanical notes include:

• Pin tip shift tolerance: ±0.4 mm.
• Foreign material on a segment: ≤ 10 mil (approx. 0.254 mm).
• Bending of the reflector: ≤ 1% of its length.
• Bubbles within a segment: ≤ 10 mil.
• Ink contamination on the surface: ≤ 20 mil (approx. 0.508 mm).
• Recommended PCB hole diameter for pins: 1.0 mm.

3.2 Pin Configuration and Circuit Diagram

The display has a 16-pin configuration, though not all pins are physically present or electrically connected. It is a multiplexed common anode type. The internal circuit diagram shows the four common anode pins (one for each digit) and the shared cathode pins for each segment (A-G and DP). The pin connection table is as follows:

• Pin 1: Common Anode for Digit 1
• Pin 2: Common Anode for Digit 2
• Pin 3: Cathode for Segment D
• Pin 4: Common Anode for Segments L1, L2, L3 (likely for custom icons)
• Pin 5: Cathode for Segment E
• Pin 6: Common Anode for Digit 3
• Pin 7: Cathode for Decimal Point (DP)
• Pin 8: Common Anode for Digit 4
• Pin 9: No Connection
• Pin 10: No Pin
• Pin 11: Cathode for Segment F
• Pin 12: No Pin
• Pin 13: Cathode for Segment C and L3
• Pin 14: Cathode for Segment A and L1
• Pin 15: Cathode for Segment G
• Pin 16: Cathode for Segment B and L2

4. Performance Curves and Analysis

The datasheet includes typical characteristic curves which are essential for detailed circuit design. These curves graphically represent the relationship between key parameters under varying conditions. Designers should refer to these for:

• Forward Current vs. Forward Voltage (I_F-V_F Curve): Shows the non-linear relationship, critical for designing the current-limiting circuitry.
• Luminous Intensity vs. Forward Current (I_V-I_F Curve): Indicates how brightness scales with drive current, helping to optimize for desired brightness and power consumption.
• Luminous Intensity vs. Ambient Temperature (I_V-T_a Curve): Demonstrates the derating of light output as temperature increases, which is vital for applications in high-temperature environments.
• Relative Spectral Distribution: Illustrates the intensity of light emitted across the wavelength spectrum, centered around the peak wavelength of 650 nm.

5. Application Guidelines and Cautions

5.1 Design and Application Considerations

• Intended Use: For ordinary electronic equipment (office, communication, household). Not recommended for safety-critical systems (aviation, medical, etc.) without prior consultation and evaluation.
• Drive Circuit Design:
  • Constant Current Drive: Highly recommended to ensure stable luminous intensity and longevity.
  • Voltage Range: The circuit must accommodate the full forward voltage (V_F) range (2.0V to 2.7V considering tolerance) to deliver the intended current.
  • Protection: Incorporate protection against reverse voltages and transient spikes during power cycling.
  • Current Derating: Select operating current after considering the maximum ambient temperature, as the maximum continuous current derates above 25°C.
• Thermal & Environmental:
  • Avoid operating above recommended current/temperature to prevent rapid light degradation.
  • Avoid rapid temperature changes in humid environments to prevent condensation on the display.
• Mechanical Handling: Do not apply abnormal force to the display body during assembly. If a decorative film is applied, avoid having it in direct contact with a front panel/cover as external force may shift it.
• Multi-Display Assemblies: Use displays from the same luminous intensity bin to ensure uniform appearance.
• Reliability Testing: If the end product requires drop or vibration testing, the conditions should be shared for evaluation prior to design finalization.

5.2 Storage Conditions

To maintain performance and prevent issues such as pin oxidation, the display should be stored in its original packaging under the following conditions:

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

6. Soldering and Assembly Guide

The recommended soldering method is wave soldering. The critical parameter is to ensure the solder point on the PCB is at least 1.6 mm (1/16 inch) below the seating plane of the display to prevent excessive heat from reaching the plastic body and LED chips. The soldering temperature should be 260°C for a duration of 3 seconds. The temperature of the display unit itself during this process must not exceed its maximum temperature rating.

7. Technical Comparison and Positioning

The LTC-4627JD-01 positions itself as a reliable, medium-brightness numeric display solution. Its key differentiators include:

• AlInGaP Technology: Offers higher efficiency and better temperature stability compared to older GaAsP or GaP technologies for red LEDs, resulting in the \"Hyper Red\" classification with good brightness.
• 0.4-inch Digit Height: A common size offering a balance between readability and board space consumption, suitable for instrument panels, consumer appliances, and industrial controls.
• Binning for Consistency: The provision of luminous intensity bins is a mark of quality control, enabling predictable performance in volume production.
• RoHS Compliance: Meets modern environmental regulations for lead-free manufacturing.

8. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the difference between peak wavelength (650nm) and dominant wavelength (639nm)?
A: Peak wavelength is the physical point of highest spectral emission. Dominant wavelength is the single wavelength perceived by the human eye that matches the color of the light source. For this deep red LED, the eye perceives a slightly shorter wavelength than the physical peak.

Q: Why is constant current drive recommended over constant voltage?
A> LED brightness is primarily a function of current. The forward voltage (V_F) has manufacturing tolerances and varies with temperature. A constant current source ensures the same current (and thus consistent brightness) flows through each segment regardless of these V_F variations.

Q: Can I drive this display with a microcontroller directly?
A: No. The continuous current per segment is 25mA, which exceeds the typical GPIO pin current rating of a microcontroller (often 20-25mA absolute max). You must use external drivers, such as transistor arrays or dedicated LED driver ICs, which also facilitate the multiplexing required for a 4-digit display.

Q: What does \"multiplex common anode\" mean for my circuit design?
A> It means the anodes of the LEDs for each digit are connected together internally (Digit 1 anode, Digit 2 anode, etc.). To display a number, you sequentially turn on one digit's common anode at a time while applying the correct cathode pattern for the desired segments. This cycles rapidly (typically >100Hz) to create the illusion of all digits being on simultaneously, drastically reducing the required I/O pins.

9. Design and Usage Case Study

Scenario: Designing a Digital Multimeter Display
A designer is creating a 4-digit digital multimeter. They select the LTC-4627JD-01 for its readability and red color, which is common for such instruments.

1. Brightness Selection: The multimeter may be used indoors and outdoors. The designer chooses displays from Bin G (501-800 μcd) to ensure adequate brightness in various lighting conditions.
2. Drive Circuit: A dedicated multiplexing LED driver IC is selected. The designer sets the constant current to 15 mA per segment—well below the 25 mA maximum—to ensure long-term reliability and account for potential higher ambient temperatures inside the meter's enclosure.
3. PCB Layout: The recommended 1.0 mm hole diameter is used for the pins. Care is taken in the PCB layout to ensure the thermal pad (if any) and traces can handle the cumulative current when multiple segments are lit.
4. Software: The microcontroller firmware implements the multiplexing routine, cycling through the four digit anode pins at a high frequency. It also includes logic to control the right-hand decimal point (pin 7 cathode).
5. Testing: Before final assembly, a sample is tested across the operating temperature range to verify brightness consistency, ensuring the chosen drive current is appropriate even at the high end of the temperature range.

10. Operating Principle and Technology Trends

10.1 Principle of Operation

The display is based on AlInGaP LED chips. When a forward voltage exceeding the chip's bandgap voltage (around 2V) is applied, electrons and holes recombine in the active region, releasing energy in the form of photons—a process called electroluminescence. The specific composition of the AlInGaP layers determines the bandgap energy and thus the wavelength (color) of the emitted light, which in this case is in the hyper red spectrum. The seven segments are individual LEDs or groups of LED chips arranged in a figure-eight pattern. Multiplexing is an electronic technique that exploits the persistence of human vision to control many LEDs with fewer wires by lighting them in rapid sequence.

10.2 Technology Trends

While seven-segment displays remain fundamental, the broader LED display technology landscape is evolving. Trends include:

• Higher Efficiency: Ongoing material science improvements aim for higher lumens per watt (efficacy), reducing power consumption for the same brightness.
• Miniaturization: Displays with smaller digit heights and pitches are being developed for compact devices.
• Integration: Driver electronics are increasingly being integrated into display modules, simplifying system design.
• Advanced Materials: Research into materials like perovskites and quantum dots promises future displays with wider color gamuts and tunable properties. However, for standard numeric indicators, mature technologies like AlInGaP offer an optimal balance of performance, reliability, and cost.