LTC-2630JD 0.28-inch 7.0mm Digit Height AlInGaP Red LED Display Datasheet - English Technical Document

1. Product Overview

The LTC-2630JD is a compact, high-performance seven-segment display module designed for applications requiring clear numeric readouts with low power consumption. It features three digits, each with a character height of 0.28 inches (7.0 millimeters). The core technology utilizes AlInGaP (Aluminum Indium Gallium Phosphide) high-efficiency red LED chips. These chips are fabricated on a non-transparent GaAs substrate, which contributes to high contrast. The display presents a gray face with white segments, offering an excellent visual appearance under various lighting conditions.

This device is categorized as a multiplex common anode display, meaning the anodes of each digit are connected together internally, allowing for efficient control via time-division multiplexing. This design is ideal for microcontroller-based systems where minimizing pin count is crucial. The right-hand decimal point is integrated into the package. Its primary design goals are low power operation, high brightness, wide viewing angles, and solid-state reliability, making it suitable for a wide range of consumer, industrial, and instrumentation products.

2. Technical Parameters Deep Objective Interpretation

2.1 Photometric and Optical Characteristics

The optical performance is a key strength of this display. At a standard test current of 1mA per segment, the average luminous intensity ranges from a minimum of 200 µcd to a maximum of 600 µcd, with a typical value provided. This high brightness at low current is a direct result of the AlInGaP material's efficiency. The dominant wavelength (λd) is specified at 640 nm, and the peak emission wavelength (λp) is 656 nm, both measured at IF=20mA, placing the output in the pure red region of the spectrum. The spectral line half-width (Δλ) is 22 nm, indicating a relatively narrow bandwidth and saturated color. Luminous intensity matching between segments is guaranteed to be within a 2:1 ratio at 10mA, ensuring uniform appearance across all activated segments of a digit.

2.2 Electrical Parameters

The electrical characteristics define the operating boundaries and conditions. The absolute maximum ratings set hard limits: a continuous forward current of 25 mA per segment (derating linearly above 25°C at 0.33 mA/°C), a peak forward current of 100 mA for pulsed operation (1/10 duty cycle, 0.1ms pulse width), and a maximum reverse voltage of 5V. The power dissipation per segment must not exceed 70 mW. Under typical operating conditions, the forward voltage (VF) per segment is between 2.1V and 2.6V when driven at 20mA. The reverse current (IR) is a maximum of 10 µA at the full 5V reverse bias. These parameters are critical for designing appropriate current-limiting resistors and driver circuits.

2.3 Thermal and Environmental Specifications

The device is rated for an operating temperature range of -35°C to +85°C, with an identical storage temperature range. This wide range ensures reliable performance in demanding environments. A specific note is provided for soldering: the device can withstand a maximum temperature of 260°C for up to 3 seconds, measured at a point 1.6mm (1/16 inch) below the seating plane of the package. Adherence to this guideline is essential to prevent thermal damage during the assembly process.

3. Binning System Explanation

The datasheet indicates that the devices are "Categorized for Luminous Intensity." This implies a binning or sorting process based on measured light output at a standard test condition (likely 1mA or 10mA). While the specific bin codes are not detailed in this document, such categorization allows designers to select parts with consistent brightness levels for their application, preventing noticeable variations in display intensity between different units in a production run. The guaranteed 2:1 intensity matching ratio further supports uniformity within a single device.

4. Performance Curve Analysis

The datasheet references "Typical Electrical / Optical Characteristic Curves" which are essential for detailed design analysis. Although the specific curves are not provided in the text excerpt, typical plots for such devices would include:

• Luminous Intensity vs. Forward Current (I-V Curve): This graph shows how light output increases with current. For AlInGaP LEDs, the relationship is generally linear at lower currents but may saturate at higher currents due to thermal effects.
• Forward Voltage vs. Forward Current: This curve is crucial for determining the voltage drop across the LED at different operating points, necessary for calculating power supply requirements and driver design.
• Luminous Intensity vs. Ambient Temperature: This plot demonstrates how brightness decreases as the junction temperature rises. Understanding this derating is vital for applications operating at high ambient temperatures.
• Spectral Distribution: A graph showing the relative intensity across wavelengths, centered around the 656 nm peak, illustrating the color purity.

Designers should consult the full datasheet with these curves to optimize drive conditions for efficiency, brightness, and longevity.

5. Mechanical and Package Information

5.1 Package Dimensions

The LTC-2630JD comes in a standard LED display package. All dimensions are provided in millimeters with a standard tolerance of ±0.25 mm unless otherwise specified. The drawing would detail the overall length, width, and height of the package, the digit spacing, the segment size, and the position and diameter of the leads. Precise mechanical data is required for creating accurate PCB footprints and ensuring proper fit within the end product's enclosure.

5.2 Pin Connection and Polarity Identification

The device has a 16-pin configuration. The pinout is clearly defined:

• Pins 2, 5, 8: Common Anode for Digit 1, Digit 2, and Digit 3 respectively.
• Pins 1, 4, 6, 7, 12, 15, 16: Cathodes for segments D, E, C, G, B, A, F respectively.
• Pin 3: Cathode for the Decimal Point (D.P.).
• Pins 9, 10, 11, 13, 14: No Connection (N.C.).

The internal circuit diagram shows the multiplexed common anode structure. Each digit's anode is separate, while the cathodes for the same segment across all three digits are connected internally. This architecture is standard for multiplexed displays and minimizes the required driver pins.

5.3 Polarity and Segment Identification

The display uses a common anode configuration. Applying a positive voltage to a specific digit's anode pin while sinking current through a segment's cathode pin will illuminate that segment on that digit. The standard seven-segment labeling (A through G) and the decimal point are used. The "Rt.H.Decimal" notation confirms the decimal point is located on the right-hand side of the digit set.

6. Soldering and Assembly Guidelines

The key assembly specification is the soldering temperature profile. The component can withstand a peak temperature of 260°C for a maximum duration of 3 seconds. This measurement must be taken at the lead, 1.6mm below the body of the package. Standard lead-free (SnAgCu) reflow profiles are typically compatible with this rating. It is critical to follow these limits to prevent delamination, cracking, or degradation of the internal LED chips and wire bonds. Pre-baking may be recommended if the devices have been exposed to moisture, per standard MSL (Moisture Sensitivity Level) procedures, though the specific MSL level is not stated in this excerpt.

7. Application Suggestions

7.1 Typical Application Scenarios

The LTC-2630JD is ideal for any application requiring a compact, low-power, highly readable numeric display. Common uses include:

• Test and Measurement Equipment: Multimeters, frequency counters, power supplies.
• Consumer Electronics: Audio equipment (amplifiers, receivers), kitchen appliances, clocks.
• Industrial Controls: Panel meters, process indicators, timer displays.
• Automotive Aftermarket: Gauges and readouts where bright red is a common color.

7.2 Design Considerations and Driver Circuit

To use this display effectively, a multiplexing driver circuit is required. A microcontroller with sufficient I/O pins or a dedicated display driver IC (like a MAX7219 or HT16K33) is typically used. The design process involves:

1. Current Limiting: Calculate series resistors for each cathode line based on the desired segment current and the forward voltage drop. For example, to achieve 10mA per segment with a 5V supply and a VF of 2.4V, a resistor of R = (5V - 2.4V) / 0.01A = 260Ω (use 270Ω standard value) is needed.
2. Multiplexing Frequency: Choose a refresh rate high enough to avoid visible flicker, typically above 60 Hz per digit. With three digits, the scan rate should be >180 Hz. The human eye perceives a steady image due to persistence of vision.
3. Driver Capability: Ensure the microcontroller ports or driver IC can sink the total cathode current. When one digit is on, all its illuminated segments' currents sum at the common anode. If 7 segments are on at 10mA each, the anode driver must source 70mA.
4. Power Management: The low current operation (as low as 1mA per segment) makes this display suitable for battery-powered devices. Dynamic adjustment of current based on ambient light can further save power.

8. Technical Comparison and Differentiation

Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) red LEDs, the AlInGaP material in the LTC-2630JD offers significantly higher luminous efficiency. This translates to greater brightness at the same current or equivalent brightness at much lower current, directly enabling lower power consumption. Compared to some very low-cost displays, the "categorized for luminous intensity" and guaranteed segment matching provide a more professional and uniform appearance. The 0.28-inch digit height offers a good balance between readability and board space, being larger than ultra-miniature displays but more compact than 0.5-inch or larger digits.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the minimum current needed to see a glow?

A: While the device is characterized down to 1mA, LEDs can emit visible light at much lower currents, perhaps in the tens of microamps. However, for reliable and consistent brightness in an application, operating within the characterized range (1mA and above) is recommended.

Q: Can I drive this display with a constant voltage source without a current-limiting resistor?

A: No. LEDs are current-driven devices. Connecting them directly to a voltage source exceeding their forward voltage will cause excessive current to flow, potentially destroying the segment almost instantly due to thermal runaway. A series current-limiting resistor or a constant-current driver is always mandatory.

Q: Why are there "No Connection" pins?

A: The package likely has a standard 16-pin DIP (Dual In-line Package) footprint. Using N.C. pins helps with mechanical stability during soldering and may be a legacy of a shared package design used for other display variants with more features (e.g., with colon or additional symbols).

Q: How do I calculate the power consumption of the display?

A: For a multiplexed display, average power is calculated. For example, with 3 digits, each segment driven at 10mA (VF=2.4V), and one digit active at a time (1/3 duty cycle), the average current per segment is 10mA / 3 ≈ 3.33mA. If 7 segments are on per digit, average power ≈ 7 segments * 3.33mA * 2.4V = ~56 mW per digit. Total display power would be approximately three times this if all digits are constantly on, but multiplexing shares the load over time.

10. Design and Usage Case Study

Case: Designing a Portable Digital Thermometer

A designer is creating a handheld thermometer that must run for months on a single 9V battery. They select the LTC-2630JD for its low current capability. The microcontroller operates at 3.3V. The designer chooses to drive each segment at 2mA for adequate indoor readability. Using a 3.3V supply and a VF of 2.4V, the current-limiting resistor is (3.3V - 2.4V) / 0.002A = 450Ω. A multiplexing driver IC with low quiescent current is selected. The display is only activated when a button is pressed, further conserving power. The gray face provides good contrast in both dim and bright ambient light, and the high efficiency of the AlInGaP LEDs ensures the numbers are clear even at the low 2mA drive current, meeting the long battery life goal.

11. Operating Principle Introduction

A seven-segment display is an assembly of light-emitting diodes (LEDs) arranged in the pattern of the number eight. By selectively illuminating specific segments (labeled A through G), all decimal digits from 0 to 9 can be formed. The LTC-2630JD contains three such digit assemblies in one package. It uses a common anode multiplexing scheme. Internally, the anodes (positive terminals) of all LEDs belonging to Digit 1 are connected to pin 2, Digit 2 to pin 5, and Digit 3 to pin 8. The cathodes (negative terminals) of all 'A' segments (from all three digits) are connected together to pin 15, all 'B' segments to pin 12, and so on. To display a number, the microcontroller:

1. Sets the anode pin for the target digit to a logic HIGH (or connects it to Vcc via a transistor).

2. Sets the cathode pins for the segments that should be ON to logic LOW (ground), sinking current through them.

3. After a short time (e.g., 5ms), it turns off that digit's anode.

4. It repeats steps 1-3 for the next digit. This happens so quickly that all digits appear to be continuously lit.

12. Technology Trends and Context

The use of AlInGaP material represents an advancement over older LED technologies for red and amber colors, offering superior efficiency and brightness. The trend in display technology continues towards even higher efficiency materials like InGaN (for blue/green/white) and micro-LEDs. However, for standard segmented displays, AlInGaP remains a dominant and cost-effective solution for red/orange/yellow outputs. Another trend is the integration of driver circuitry directly into the display module ("intelligent displays"), reducing the external component count and microcontroller overhead. While the LTC-2630JD is a traditional passive component, its low-power characteristics align well with the overarching industry demands for energy efficiency and longer battery life in portable devices. Future developments may focus on even lower voltage operation and broader temperature ranges for automotive and industrial applications.