LTC-4627JG LED Display Datasheet - 0.4-inch Digit Height - Green (571nm) - 2.6V Forward Voltage - 70mW Power - English Technical Document

1. Product Overview

The LTC-4627JG is a quadruple-digit, seven-segment alphanumeric display module designed for applications requiring clear, bright numeric and limited character readouts. Its primary function is to visually represent numbers and some letters through individually addressable segments. The core technology utilizes AlInGaP (Aluminum Indium Gallium Phosphide) LED chips grown on a non-transparent GaAs substrate. This material system is chosen for its high efficiency and excellent performance in the green-yellow wavelength region. The display features a gray face with white segment markings, providing high contrast for optimal readability under various lighting conditions. The 0.4-inch (10.0 mm) digit height makes it suitable for medium-distance viewing in instrumentation, industrial controls, and consumer electronics where space is at a premium but clarity is essential.

1.1 Key Features and Advantages

• 0.4-Inch Digit Height: Offers a balanced size for good visibility without excessive panel space consumption.
• Continuous Uniform Segments: Ensures a consistent, gapless appearance of illuminated characters, enhancing aesthetic quality and readability.
• Low Power Requirement: The AlInGaP technology enables high brightness at relatively low drive currents, contributing to energy-efficient designs.
• Excellent Character Appearance: High contrast between the gray face and white segments, combined with uniform illumination, results in sharp, well-defined characters.
• High Brightness & High Contrast: The inherent brightness of AlInGaP LEDs and the chosen color scheme deliver superior visibility even in brightly lit environments.
• Wide Viewing Angle: The LED chip and package design allow for clear viewing from a broad range of angles, typical of LED segment displays.
• Solid-State Reliability: As a semiconductor device, it offers long operational life, shock resistance, and vibration tolerance compared to mechanical displays.
• Categorized for Luminous Intensity: Devices are binned for intensity, allowing designers to select parts for consistent brightness levels across multiple units in an assembly.
• Lead-Free Package (RoHS Compliant): Manufactured in accordance with environmental regulations restricting hazardous substances.

1.2 Device Identification and Configuration

The part number LTC-4627JG specifies a multiplexed, common-anode display with AlInGaP green LEDs. The \"JG\" suffix typically indicates the green color and specific package or feature set. The display includes four full digits (0-9) and a right-hand decimal point for each digit. It employs a multiplexed common anode configuration, which reduces the number of required driver pins by time-sharing the common connections for each digit.

2. Technical Specifications Deep Dive

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation at or near these limits is not recommended for normal use.

• Power Dissipation per Segment: 70 mW. This is the maximum power that can be safely dissipated by a single LED segment without causing thermal damage.
• Peak Forward Current per Segment: 60 mA. This is the maximum allowable pulsed current, typically specified under conditions of 1/10 duty cycle and 0.1 ms pulse width. It is used for brief, high-intensity flashes.
• Continuous Forward Current per Segment: 25 mA at 25°C. This current must be derated linearly by 0.33 mA/°C as ambient temperature (Ta) rises above 25°C. For example, at 50°C, the maximum continuous current would be 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Reverse Voltage per Segment: 5 V. Exceeding this voltage in reverse bias can cause junction breakdown.
• Operating & Storage Temperature Range: -35°C to +85°C. The device is rated for reliable operation and storage within this industrial temperature range.
• Solder Temperature: Maximum 260°C for a maximum of 3 seconds, measured 1.6 mm (1/16 inch) below the seating plane. This is critical for wave or reflow soldering processes to prevent package damage.

2.2 Electrical & Optical Characteristics

These are typical operating parameters measured at an ambient temperature (Ta) of 25°C, providing the expected performance under normal conditions.

• Average Luminous Intensity (I_V): 200 µcd (Min), 464 µcd (Typ) at I_F = 1 mA. This is the light output, measured using a sensor filtered to match the human eye's photopic response (CIE curve). The wide range indicates binning for intensity.
• Peak Emission Wavelength (λ_p): 571 nm (Typ) at I_F = 20 mA. This is the wavelength at which the spectral output is strongest, in the green-yellow region.
• Spectral Line Half-Width (Δλ): 15 nm (Typ) at I_F = 20 mA. This indicates the spectral purity; a narrower width means a more monochromatic color.
• Dominant Wavelength (λ_d): 572 nm (Typ) at I_F = 20 mA. This is the single wavelength perceived by the human eye to match the color of the LED.
• Forward Voltage per Segment (V_F): 2.05 V (Min), 2.6 V (Typ) at I_F = 20 mA. This is the voltage drop across the LED when conducting the specified current. Circuit design must accommodate the maximum V_F.
• Reverse Current per Segment (I_R): 100 µA (Max) at V_R = 5 V. This is the small leakage current when the LED is reverse-biased.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 (Max) at I_F = 1 mA. This specifies the maximum allowable ratio between the brightest and dimmest segments within a single device, ensuring uniformity.

3. Mechanical & Package Information

3.1 Package Dimensions

The display conforms to a standard dual in-line package (DIP) footprint. All critical dimensions are provided in millimeters with a general tolerance of ±0.25 mm unless otherwise specified on the dimensional drawing. This includes the overall length, width, and height, the spacing between digits, the segment dimensions, and the pin spacing and diameter. The exact mechanical drawing is essential for PCB (Printed Circuit Board) layout to ensure proper fit and alignment with the front panel cutout.

3.2 Pin Configuration and Internal Circuit

The device has a 16-pin configuration, though not all positions are populated (pins 10 and 12 are \"NO PIN\"). The internal circuit diagram shows a multiplexed common anode structure. Each of the four digits has its own common anode pin (pins 1, 2, 6, 8). The segment cathodes (A-G, DP) are shared across all digits. Additionally, there are connections for three separate indicator LEDs (L1, L2, L3) which share a common anode (pin 4) and have cathodes tied to segment cathodes A/B/C respectively. Pin 9 is noted as \"NO CONNECTION.\" This pinout is crucial for designing the multiplexing driver circuit, which sequentially energizes each digit's common anode while presenting the segment data for that digit on the shared cathode lines.

4. Application Guidelines and Cautions

4.1 Design and Usage Considerations

Intended Use: This display is designed for ordinary electronic equipment in office, communication, and household applications. For safety-critical systems (aviation, medical, transportation), consultation prior to use is mandatory.

Ratings Compliance: Adherence to Absolute Maximum Ratings is essential to prevent damage. The manufacturer assumes no liability for failures resulting from non-compliance.

Current and Thermal Management: Exceeding recommended drive currents or operating temperatures will accelerate light output degradation (lumen depreciation) and can lead to premature failure. Constant current driving is strongly recommended over constant voltage driving to ensure stable brightness and longevity, as it compensates for the LED's negative temperature coefficient and V_F variation.

Circuit Protection: The driving circuit must incorporate protection against reverse voltages and voltage transients during power cycling. Reverse bias can induce metal migration within the semiconductor, increasing leakage or causing shorts.

Forward Voltage Consideration: The power supply and current-limiting circuitry must be designed to deliver the intended drive current across the entire range of possible V_F values (from Min to Max).

Environmental Factors: Rapid ambient temperature changes, especially in humid environments, should be avoided as they can cause condensation on the display, potentially leading to electrical or optical issues.

Mechanical Handling: Avoid applying abnormal force to the display body during assembly. If a decorative film is applied, ensure it does not make tight contact with the front panel/cover, as external force may shift it.

Binning for Consistency: When assembling multiple displays in one unit, using devices from the same luminous intensity bin is recommended to prevent noticeable brightness or hue differences between units.

Reliability Testing: If the end product requires the display to undergo specific drop or vibration tests, the conditions should be shared with the manufacturer for evaluation beforehand.

4.2 Storage and Handling Conditions

Standard Storage (DIP Package): Products in original packaging should be stored at 5°C to 30°C with relative humidity below 60% RH. Non-compliance can lead to pin oxidation, requiring replating before use. Long-term storage of large inventories is discouraged. If the moisture barrier bag has been open for more than 6 months, baking at 60°C for 48 hours is recommended, followed by assembly within one week.

SMD Display Storage (Note): While this is a DIP part, the datasheet includes a note for SMD variants: once the factory-sealed bag is opened, the device should be used within 168 hours (7 days) when stored at <60% RH and 5-30°C, corresponding to a Moisture Sensitivity Level (MSL) of 3. This highlights the importance of moisture control for modern LED packages.

5. Performance Curves and Graphical Data

The datasheet references typical performance curves which are essential for detailed design analysis. These graphs visually represent the relationship between key parameters, allowing engineers to interpolate values not explicitly listed in the tables. While the specific curves are not detailed in the provided text, they typically include:

Relative Luminous Intensity vs. Forward Current (I-V Curve): Shows how light output increases with drive current, usually in a sub-linear fashion at higher currents due to thermal effects.

Forward Voltage vs. Forward Current: Illustrates the diode's exponential I-V characteristic.

Relative Luminous Intensity vs. Ambient Temperature: Demonstrates the decrease in light output as junction temperature rises, a critical factor for thermal design.

Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~571nm and the spectral width. These curves enable designers to optimize drive conditions, predict performance under non-standard temperatures, and understand the color characteristics of the LED.

6. Typical Application Scenarios and Design Notes

The LTC-4627JG is ideally suited for applications requiring a compact, reliable, and bright numeric display. Common uses include:

Test and Measurement Equipment: Digital multimeters, frequency counters, power supplies, where 4 digits provide sufficient resolution.

Industrial Control Panels: Process indicators, timer displays, counter readouts on machinery.

Consumer Appliances: Microwave ovens, audio equipment, climate control systems.

Automotive Aftermarket Displays: Gauges and readouts where environmental robustness is needed.

Design Implementation: Implementing this display requires a microcontroller or dedicated driver IC capable of multiplexing. The driver must source sufficient current for the common anode pins (digit current = segment current * number of lit segments in that digit) and sink current for the segment cathode pins. Current-limiting resistors are mandatory for each segment cathode when using a constant voltage supply. A well-designed multiplexing routine with appropriate persistence and refresh rate (typically >60 Hz) is necessary to avoid flicker. The wide viewing angle makes it suitable for panels viewed from various positions.