LTD-6730JD LED Display Datasheet - 0.56-inch Digit Height - Hyper Red Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTD-6730JD is a dual-digit, seven-segment display module designed for applications requiring clear numeric readouts. Its primary function is to visually represent two digits (0-9 and some letters) using individually addressable LED segments. The core technology is based on AlInGaP (Aluminum Indium Gallium Phosphide) semiconductor material, specifically engineered to emit light in the hyper red spectrum. This device is categorized as a common anode type display, meaning the anodes of the LEDs for each digit are connected together internally, simplifying the driving circuitry when using current-sinking drivers.

The display features a character height of 0.56 inches (14.22 mm), offering a balance between readability and compact size. It is presented with a gray face and white segment markings, which enhances contrast and legibility when the segments are illuminated. The device is designed for low-power operation, making it suitable for battery-powered or energy-conscious applications where efficient illumination is critical.

2. Technical Parameters Deep Objective Interpretation

2.1 Photometric and Optical Characteristics

The optical performance is defined under standard test conditions at an ambient temperature (Ta) of 25\u00b0C. The key parameter, Average Luminous Intensity (Iv), has a typical value of 700 \u00b5cd when driven at a forward current (IF) of 1 mA per segment. The minimum specified value is 320 \u00b5cd, and there is no maximum limit listed, indicating a focus on ensuring a minimum brightness level. The luminous intensity matching ratio between segments is specified at 2:1 maximum, which defines the allowable variation in brightness between different segments to ensure uniform appearance.

The color characteristics are defined by wavelength. The Peak Emission Wavelength (\u03bbp) is typically 650 nm, while the Dominant Wavelength (\u03bbd) is typically 639 nm when driven at IF=20mA. The slight difference between peak and dominant wavelength is common in LEDs. The Spectral Line Half-Width (\u0394\u03bb) is 20 nm, indicating the spectral purity or the spread of the emitted light's wavelength around the peak. This combination places the emission firmly in the hyper red region of the visible spectrum.

2.2 Electrical Characteristics

The electrical parameters define the operating boundaries and conditions for the device. The Forward Voltage per segment (VF) ranges from 2.1V to 2.6V at a test current of 1 mA. This parameter is crucial for designing the current-limiting circuitry. The Reverse Current per segment (IR) is specified at a maximum of 100 \u00b5A when a Reverse Voltage (VR) of 5V is applied, indicating the level of leakage when the LED is reverse-biased.

The Absolute Maximum Ratings establish the limits beyond which permanent damage may occur. The Continuous Forward Current per segment is rated at 25 mA at 25\u00b0C, with a derating factor of 0.33 mA/\u00b0C. This means the allowable continuous current decreases as ambient temperature increases. For pulsed operation, a Peak Forward Current of 90 mA is allowed under specific conditions (1/10 duty cycle, 0.1 ms pulse width), which can be used for multiplexing or achieving higher instantaneous brightness. The maximum Power Dissipation per segment is 70 mW. The maximum Reverse Voltage per segment is 5V.

2.3 Thermal and Environmental Specifications

The device is rated for an Operating Temperature Range of -35\u00b0C to +85\u00b0C. The identical Storage Temperature Range indicates the component's robustness when not powered. A critical assembly parameter is the Solder Temperature rating: the device can withstand a maximum temperature of 260\u00b0C for a maximum of 3 seconds, measured at a point 1.6mm (1/16 inch) below the seating plane of the package. This is a standard rating for wave or reflow soldering processes.

3. Mechanical and Packaging Information

The device is supplied in a standard dual-digit seven-segment package. The provided dimensions define the physical footprint, hole spacing, and overall height, which are essential for PCB (Printed Circuit Board) layout and mechanical integration into a final product. The drawing specifies that all dimensions are in millimeters, with standard tolerances of \u00b10.25 mm unless otherwise noted. The package includes the gray face with white segment markings and the necessary pins for electrical connection.

4. Pin Connection and Internal Circuit

The device has an 18-pin configuration. The pinout is as follows: Pins 1-12 and 15 are cathodes for specific segments (A, B, C, D, E, F, G, H, J, DP) for Digit 1 and Digit 2. The segment mapping (e.g., which pin controls segment 'A' of Digit 2) is explicitly defined. Pins 13 and 14 are the Common Anodes for Digit 2 and Digit 1, respectively. Pins 16, 17, and 18 are listed as "No Connection" (NC). The internal circuit diagram shows that each digit is a common anode configuration, where the anode is shared among all seven segments (plus decimal point) of that digit, and each segment has its own individual cathode pin. This architecture is optimal for multiplexing, where the anodes of each digit are turned on sequentially at a high frequency while the corresponding cathode pins are driven to illuminate the desired segments.

5. Performance Curve Analysis

While the specific graphs are not detailed in the provided text, typical curves for such a device would include several key relationships. The Forward Current vs. Forward Voltage (I-V) curve shows the exponential relationship characteristic of a diode; understanding this curve is vital for selecting the correct series resistor or designing a constant-current driver. The Luminous Intensity vs. Forward Current curve typically shows a near-linear relationship at lower currents, saturating at higher currents. The Luminous Intensity vs. Ambient Temperature curve is critical, as LED output generally decreases with increasing junction temperature. For a colored LED like this hyper red type, the Spectral Distribution curve would show the intensity of light emitted across different wavelengths, centered around 650 nm.

6. Application Suggestions

6.1 Typical Application Scenarios

This display is suited for a wide range of applications requiring clear, reliable numeric indication. Common uses include instrumentation panels (e.g., multimeters, frequency counters), consumer appliances (microwaves, ovens, washing machines), industrial control readouts, test and measurement equipment, and point-of-sale terminals. Its low current requirement makes it a candidate for portable, battery-operated devices.

6.2 Design Considerations and Driving Circuitry

Designing with this display requires a driver circuit capable of sinking the segment current. Since it is a common anode display, the anodes (pins 13 and 14) should be connected to a positive voltage supply (Vcc) through a current-limiting resistor or, more commonly, switched by a transistor or a dedicated driver IC's output pin. The cathode pins (1-12, 15) are connected to the current-sinking outputs of the driver (e.g., a microcontroller's GPIO pin, a shift register, or a dedicated LED driver).

To control both digits, multiplexing is the standard approach. The circuit would rapidly alternate between turning on the anode of Digit 1 (while driving the cathodes for Digit 1's desired segments) and then turning on the anode of Digit 2 (while driving the cathodes for Digit 2's desired segments). The human eye's persistence of vision blends these rapid flashes into a stable, two-digit image. The multiplexing frequency must be high enough to avoid visible flicker, typically above 60 Hz. When multiplexing, the instantaneous current per segment can be higher than the DC rating (using the peak current rating as a guide) to achieve the same average brightness, but thermal and duty cycle limits must be observed.

Current limiting is mandatory. Even with multiplexing, a series resistor for each segment cathode or the use of a constant-current driver is required to prevent excessive current from damaging the LED chips. The resistor value can be calculated using Ohm's Law: R = (Vcc - VF) / IF, where VF is the forward voltage of the LED (use the max value of 2.6V for a conservative design), Vcc is the supply voltage, and IF is the desired forward current.

7. Technical Comparison and Features

The listed features highlight its competitive advantages: Continuous Uniform Segments ensure a smooth, gapless appearance of the lit number. High Brightness & High Contrast, facilitated by the AlInGaP technology and gray/white finish, ensures readability in various lighting conditions. Wide Viewing Angle is a benefit of the LED technology and package design. Solid State Reliability refers to the inherent robustness of LEDs compared to mechanical or filament-based displays. Low Power Requirement is a key feature for modern electronic design. The device being Categorized for Luminous Intensity means units are binned or tested to meet specific brightness thresholds, providing consistency in production.

8. Common Questions Based on Technical Parameters

Q: What is the difference between "Peak Wavelength" and "Dominant Wavelength"?
A: Peak Wavelength is the single wavelength where the emission spectrum is most intense. Dominant Wavelength is the single wavelength of monochromatic light that would match the perceived color of the LED's light. They are often close but not identical due to the shape of the LED's emission spectrum.

Q: Can I drive this display directly from a 5V microcontroller pin?
A: No, not directly. You must use a current-limiting resistor in series with each segment cathode. Connecting an LED directly to a voltage source like a GPIO pin (configured as an output) would attempt to draw excessive current, potentially damaging both the LED and the microcontroller pin.

Q: Why are there "No Connection" pins?
A: The 18-pin package is likely a standard footprint used for various display configurations. For this specific dual-digit model, only 15 pins are electrically active. The NC pins provide mechanical stability and align with the standard socket or PCB layout.

Q: How do I calculate the power consumption?
A: For a non-multiplexed, static display: Power = (Number of lit segments) * (Forward Current per segment) * (Forward Voltage per segment). For a multiplexed display, the average current per segment is IF * Duty Cycle. The total power is the sum for all lit segments across both digits, considering their respective duty cycles (e.g., 50% for each digit in a two-digit multiplex).

9. Soldering and Assembly Guidelines

Adherence to the specified soldering profile is critical to prevent thermal damage to the internal LED chips, wire bonds, and the plastic package. The maximum solder temperature of 260\u00b0C for 3 seconds at 1.6mm below the seating plane is a key parameter for reflow soldering. Standard lead-free (SAC) reflow profiles typically have a peak temperature in this range. For hand soldering, a temperature-controlled iron should be used, and contact time with the pins should be minimized. After soldering, the device should be allowed to cool naturally. Avoid subjecting the display face to mechanical stress or cleaning solvents that may damage the plastic or markings.

10. Principle of Operation

The device operates on the principle of electroluminescence in a semiconductor p-n junction. The AlInGaP material system is used to create the junction. When a forward voltage exceeding the junction's threshold (approximately 2.1-2.6V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region where they recombine. In AlInGaP LEDs, this recombination releases energy primarily in the form of photons (light) in the red to orange-yellow part of the spectrum, depending on the exact alloy composition. The non-transparent GaAs substrate helps direct light output upwards through the top of the chip, enhancing brightness from the viewing side. Each segment of the display contains one or more of these LED chips connected in parallel.