LTC-2630AJD 7-Segment LED Display Datasheet - 0.28-inch Digit Height - AlInGaP Red - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTC-2630AJD is a compact, high-performance triple-digit seven-segment display designed for applications requiring clear numeric readouts with low power consumption. Its primary function is to provide a visual numeric output in electronic devices, instrumentation, consumer electronics, and industrial control panels. The core advantage of this device lies in its utilization of advanced AlInGaP (Aluminum Indium Gallium Phosphide) LED technology, which offers superior efficiency and brightness compared to traditional materials. The target market includes designers of portable battery-operated devices, panel meters, test equipment, and any application where space, power efficiency, and readability are critical constraints.

1.1 Core Features and Advantages

• Digit Height: Features a 0.28-inch (7.0 mm) character height, offering a good balance between size and visibility.
• Segment Uniformity: Provides continuous, uniform segments for excellent character appearance and readability.
• Low Power Operation: Specifically engineered for low power requirement, enabling operation in power-sensitive designs.
• Optical Performance: Delivers high brightness and high contrast, ensuring clear visibility even in well-lit environments.
• Viewing Angle: Offers a wide viewing angle, making the display legible from various positions.
• Reliability: Benefits from solid-state reliability inherent to LED technology, with no moving parts and long operational life.
• Quality Assurance: Devices are categorized for luminous intensity, ensuring consistent brightness levels across production batches.

2. Technical Specifications Deep Dive

This section provides a detailed, objective analysis of the device's key electrical, optical, and thermal parameters as defined in the datasheet.

2.1 Photometric and Optical Characteristics

Measured at an ambient temperature (Ta) of 25°C, the optical performance is defined under specific test conditions.

• Average Luminous Intensity (Iv): Ranges from a minimum of 200 μcd to a typical maximum of 600 μcd when driven at a forward current (IF) of 1mA per segment. This parameter is crucial for determining the display's brightness under normal operating conditions.
• Peak Emission Wavelength (λp): Characteristic of the AlInGaP material, though a specific value is not provided in the extracted content. Typically, AlInGaP red LEDs emit in the 620-630nm range.
• Spectral Line Half-Width (Δλ): Has a maximum value of 22 nm at IF=20mA, indicating the spectral purity of the emitted red light.
• Dominant Wavelength (λd): Is 640 nm at IF=20mA. This is the wavelength perceived by the human eye and defines the color as a specific shade of red.
• Luminous Intensity Matching Ratio (Iv-m): Has a maximum ratio of 2:1 between segments when driven at IF=10mA. This ensures uniformity in brightness across all segments of a digit.

2.2 Electrical Characteristics

• Forward Voltage per Segment (VF): Ranges from 2.1V (min) to 2.6V (max) at a forward current of 20mA. This is a key parameter for designing the driving circuitry and calculating power dissipation.
• Reverse Current per Segment (IR): Has a maximum value of 10 μA when a reverse voltage (VR) of 5V is applied, indicating good diode characteristics.
• Low Current Capability: A significant feature is its design for low current operation. The segments are matched and tested for excellent performance at currents as low as 1mA per segment, which is directly applicable for battery-powered devices.

2.3 Absolute Maximum Ratings and Thermal Management

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

• Power Dissipation per Segment: Maximum of 70 mW.
• Peak Forward Current per Segment: 100 mA, but only under pulsed conditions (1/10 duty cycle, 0.1ms pulse width).
• Continuous Forward Current per Segment: 25 mA at 25°C. This rating derates linearly at a rate of 0.33 mA/°C as ambient temperature increases above 25°C. This derating is critical for thermal design.
• Reverse Voltage per Segment: Maximum of 5V.
• Operating Temperature Range: -35°C to +85°C.
• Storage Temperature Range: -35°C to +85°C.

3. Binning and Categorization System

The datasheet indicates that the devices are \"categorized for luminous intensity.\" This implies a binning process.

• Luminous Intensity Binning: Devices are tested and sorted into groups (bins) based on their measured luminous intensity at a standard test current (likely 1mA or 10mA). This ensures designers receive displays with consistent brightness levels, which is vital for multi-digit displays where uniformity is key.
• Forward Voltage Binning: While not explicitly stated, the given VF range (2.1V to 2.6V) suggests there may be forward voltage variation. For critical applications, consulting the manufacturer for specific binning details is recommended.

4. Performance Curve Analysis

The datasheet references \"Typical Electrical / Optical Characteristic Curves.\" While the specific graphs are not provided in the text, standard curves for such LEDs would typically include:

• IV (Current-Voltage) Curve: Shows the relationship between forward current (IF) and forward voltage (VF). It is non-linear, with a turn-on voltage around 1.8-2.0V for AlInGaP red LEDs.
• Luminous Intensity vs. Forward Current (Iv-IF): This curve shows how brightness increases with current. It is generally linear at lower currents but may saturate at higher currents due to thermal effects.
• Luminous Intensity vs. Ambient Temperature (Iv-Ta): Shows how brightness decreases as the ambient temperature rises. This is crucial for designing systems that operate over the full temperature range.
• Spectral Distribution: A plot of relative intensity vs. wavelength, showing the peak at the dominant wavelength (640 nm) and the spectral width.

5. Mechanical and Package Information

5.1 Physical Dimensions

The package drawing is referenced. Key notes include that all dimensions are in millimeters, with standard tolerances of ±0.25 mm (0.01 inch) unless otherwise specified. The display has a gray face with white segments for high contrast.

5.2 Pin Configuration and Internal Circuit

The device is a multiplex common anode type with a right-hand decimal point. The pinout for the 16-pin package is as follows:

• 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)
• Pins 9, 10, 11, 13, 14: No Connection (N/C)
• Pin 12: Cathode B
• Pin 15: Cathode A
• Pin 16: Cathode F

The internal circuit diagram shows that each digit's segments (A-G, DP) share a common anode connection for that specific digit. This multiplexed architecture reduces the number of required driver pins from 24 (3 digits * 8 segments) to 11 (3 anodes + 8 cathodes).

6. Soldering and Assembly Guidelines

• Reflow Soldering: The maximum allowable solder temperature is 260°C. This temperature should be applied for a maximum duration of 3 seconds, measured at a point 1.6mm (1/16 inch) below the seating plane of the component. Exceeding these limits can damage the LED chips or the package.
• Hand Soldering: If hand soldering is necessary, a temperature-controlled iron should be used with a quick operation time (typically < 3 seconds per pin) to avoid heat damage.
• Storage Conditions: Devices should be stored within the specified storage temperature range of -35°C to +85°C in a dry environment to prevent moisture absorption, which can cause \"popcorning\" during reflow.

7. Application Recommendations

7.1 Typical Application Scenarios

• Portable Instrumentation: Multimeters, thermometers, tachometers where low power consumption is paramount.
• Consumer Electronics: Audio equipment displays, clock radios, appliance control panels.
• Industrial Controls: Panel meters for voltage, current, or process variable display.
• Automotive Aftermarket: Displays for auxiliary gauges (boost, voltage, temperature).

7.2 Design Considerations and Driving Circuitry

• Multiplexing Driver: A microcontroller or dedicated display driver IC must be used to sequentially activate the three common anodes (Digits 1, 2, 3) while providing the appropriate cathode signals for the desired segments. The refresh rate must be high enough (>60Hz) to avoid visible flicker.
• Current Limiting: External current-limiting resistors are mandatory for each cathode line (or integrated into the driver IC) to set the forward current (e.g., 1mA, 10mA, 20mA) based on the desired brightness and power budget. The resistor value is calculated using R = (Vcc - VF) / IF.
• Power Dissipation: Ensure the continuous forward current per segment does not exceed the derated maximum for the application's highest ambient temperature.
• Viewing Environment: The high contrast and wide viewing angle make it suitable for applications where the display may be viewed from an angle or in ambient light.

8. Technical Comparison and Differentiation

Compared to other seven-segment display technologies:

• vs. Standard GaAsP/GaP Red LEDs: The AlInGaP material offers significantly higher luminous efficiency, resulting in brighter output at the same current or equivalent brightness at lower current. It also typically has better temperature stability.
• vs. LCD Displays: LEDs are emissive, providing their own light, making them readable in darkness without a backlight. They also have a much faster response time and a wider operating temperature range. However, they generally consume more power than reflective LCDs.
• vs. Larger Digit Displays: The 0.28-inch size offers a compact footprint ideal for space-constrained designs while maintaining good readability at short to medium viewing distances.

9. Frequently Asked Questions (FAQ)

Q: Can I drive this display with a constant DC current without multiplexing?
A: Technically yes, but it is highly inefficient. Driving all three digits statically would require 24 independent current-limited channels (3 digits * 8 segments). The multiplexed common anode design is intended to be driven with a time-division multiplexing scheme to minimize pin count and power consumption.

Q: What is the purpose of the \"No Connection\" pins?
A: The N/C pins are likely present for mechanical stability of the package or for compatibility with a standard 16-pin footprint used for other display variants (e.g., with different decimal point locations or four-digit versions). They must not be connected in the circuit.

Q: How do I calculate the appropriate current-limiting resistor value?
A: Use the formula R = (Supply Voltage - LED Forward Voltage) / Desired Forward Current. For example, with a 5V supply (Vcc), a typical VF of 2.4V, and a desired IF of 10mA: R = (5V - 2.4V) / 0.010A = 260 Ohms. Use the nearest standard value (e.g., 270 Ohms). Always consider the maximum VF (2.6V) to ensure the minimum current is acceptable.

Q: Is the decimal point driven separately?
A: Yes. The decimal point (D.P.) has its own dedicated cathode (Pin 3). It is not tied to the segment cathodes for any specific digit. In a multiplexing scheme, it would be illuminated when its cathode is driven low during the activation period of any digit where the decimal point should be visible.

10. Design and Usage Case Study

Scenario: Designing a Low-Power Digital Voltmeter
A designer is creating a 3-digit portable voltmeter powered by a 9V battery. The key requirements are long battery life and clear readability.

• Component Selection: The LTC-2630AJD is chosen for its low current capability (operable at 1-2mA/segment) and AlInGaP efficiency.
• Driver Circuit: A low-power microcontroller with built-in LCD/segment drivers is selected. It is configured to multiplex the three digits at a 100Hz refresh rate.
• Current Setting: The segment current is set to 1.5mA via the microcontroller's constant current sinks or external resistors. At this current, the luminous intensity is well within the specified range, providing adequate brightness.
• Power Calculation: With 8 segments (7 + DP) illuminated per digit, and 3 digits multiplexed, the average total current is approximately (8 segments * 1.5mA) = 12mA. Combined with the microcontroller and measurement circuitry, this allows for extended battery life.
• Result: The final product achieves clear 3-digit voltage display with excellent battery longevity, meeting the design goals directly enabled by this display's low-current characteristics.

11. Technology Principle Introduction

The LTC-2630AJD is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor technology grown on a non-transparent Gallium Arsenide (GaAs) substrate. When a forward voltage exceeding the diode's turn-on voltage is applied, electrons and holes recombine in the active region of the semiconductor, releasing energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, red at 640 nm. The non-transparent substrate helps improve contrast by absorbing stray light, contributing to the display's \"gray face and white segments\" appearance. The seven-segment format is a standardized pattern where individual LEDs (segments) are arranged to form all decimal numerals and some letters when selectively illuminated.

12. Technology Trends and Outlook

The evolution of seven-segment LED displays continues to focus on several key areas:

• Increased Efficiency: Ongoing material science research aims to improve the internal quantum efficiency of AlInGaP and other compound semiconductors (like InGaN for other colors), yielding higher brightness at lower currents, further extending battery life.
• Miniaturization: There is a trend towards smaller digit heights for ultra-compact devices, alongside improved photolithography to maintain segment definition and clarity.
• Integration: Display modules increasingly integrate the driver IC, current-limiting resistors, and sometimes a microcontroller into a single package or PCB assembly, simplifying the design-in process for engineers.
• Color Options: While this datasheet is for a red display, the underlying multiplexing and packaging principles apply to displays using other LED technologies for green, blue, yellow, or even full-color RGB combinations.
• Alternative Technologies: While LEDs dominate in many applications, OLED (Organic LED) technology is making inroads into small segment displays, offering potentially thinner profiles and wider viewing angles, though with different lifetime and driving characteristics.

The LTC-2630AJD represents a mature, reliable, and highly optimized solution within this technological landscape, particularly for applications prioritizing power efficiency and robustness.