LTD-6410G LED Display Datasheet - 0.56-inch Digit Height - Green Color - 2.6V Forward Voltage - 70mW Power Dissipation - English Technical Document

1. Product Overview

The LTD-6410G is a dual-digit, seven-segment alphanumeric display module utilizing green light-emitting diodes (LEDs). Its primary function is to present numeric and limited alphanumeric information in electronic devices. The core advantage of this display lies in its solid-state construction, offering high reliability, long operational life, and excellent visibility characteristics.

The device is categorized as a common anode configuration, meaning the anodes of the LEDs for each digit are connected together internally. This simplifies multiplexing drive circuits. The display features a gray face with white segment diffusers, which enhances contrast and improves readability under various lighting conditions. The target market includes a wide range of consumer and industrial electronics requiring clear, reliable numeric readouts, such as test equipment, instrumentation, point-of-sale systems, and appliance control panels.

1.1 Key Features and Device Description

The LTD-6410G incorporates several design features aimed at performance and usability:

• Digit Height: 0.56 inches (14.22 mm), providing a clear and legible character size.
• Segment Uniformity: Continuous, uniform segments ensure consistent appearance across the display area.
• Power Efficiency: Low power requirement per segment, suitable for battery-powered or energy-conscious applications.
• Optical Performance: High brightness output combined with high contrast between the lit segments and the gray background ensures excellent character appearance.
• Viewing Angle: A wide viewing angle allows the display to be read from various positions.
• Reliability: Solid-state reliability with no moving parts or filaments to wear out.
• Binning: The luminous intensity is categorized (binned), allowing for selection of displays with matched brightness levels in multi-unit applications.
• Environmental Compliance: The package is lead-free, manufactured in compliance with RoHS (Restriction of Hazardous Substances) directives.

The device uses green LED chips. The datasheet specifies two possible chip technologies: GaP (Gallium Phosphide) epitaxy on a GaP substrate, or AlInGaP (Aluminum Indium Gallium Phosphide) on a non-transparent GaAs (Gallium Arsenide) substrate. Both technologies are capable of producing the specified green emission.

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 outside these limits is not guaranteed.

• Power Dissipation per Segment (P_d): 70 mW maximum. Exceeding this can lead to overheating.
• Peak Forward Current per Segment (I_FP): 60 mA, permissible only under pulsed conditions (1/10 duty cycle, 0.1 ms pulse width). This is useful for multiplexing or achieving higher instantaneous brightness.
• Continuous Forward Current per Segment (I_F): 25 mA maximum at 25°C. This rating derates linearly at 0.33 mA/°C as ambient temperature (T_a) increases above 25°C. For example, at 50°C, the maximum continuous current would be approximately 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Reverse Voltage per Segment (V_R): 5 V maximum. Applying a higher reverse voltage can cause breakdown.
• Operating & Storage Temperature Range: -35°C to +85°C.
• Solder Temperature: The device can withstand a maximum soldering temperature of 260°C for a maximum of 3 seconds, measured 1.6mm below the seating plane of the package.

2.2 Electrical and Optical Characteristics

These are typical operating parameters measured at an ambient temperature (T_a) of 25°C.

• Average Luminous Intensity (I_V): 870 µcd (minimum), 2400 µcd (typical) when driven at a forward current (I_F) of 10 mA. This parameter is binned.
• Peak Emission Wavelength (λ_p): 565 nm (typical) at I_F=20mA. This is the wavelength at which the spectral output is strongest.
• Spectral Line Half-Width (Δλ): 30 nm (typical) at I_F=20mA. This indicates the spectral purity or bandwidth of the emitted light.
• Dominant Wavelength (λ_d): 569 nm (typical) at I_F=20mA. This is the single wavelength perceived by the human eye that matches the color of the light.
• Forward Voltage per Segment (V_F): 2.1 V (minimum), 2.6 V (typical) at I_F=20mA. Circuit design must account for this range to ensure proper current regulation.
• Reverse Current per Segment (I_R): 100 µA (maximum) when a reverse voltage (V_R) of 5V is applied. The datasheet explicitly notes that this reverse voltage condition is for test purposes only and the device should not be continuously operated under reverse bias.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 (typical). This specifies the maximum allowable ratio between the brightest and dimmest segment within a single device, ensuring uniformity.

Measurement Note: Luminous intensity is measured using a sensor and filter combination that approximates the CIE (Commission Internationale de l'Eclaiage) photopic eye-response curve, ensuring the measurement correlates with human brightness perception.

3. Binning System Explanation

The LTD-6410G employs a binning system primarily for Luminous Intensity. Displays are tested and sorted into different bins based on their measured light output at a standard test current (10mA). This allows designers to select displays with closely matched brightness levels when using multiple units in a single assembly, preventing noticeable brightness variations from one digit to the next. The datasheet specifies a typical intensity range from 870 µcd to 2400 µcd, indicating the spread across available bins. For critical applications requiring visual consistency, specifying displays from the same intensity bin is strongly recommended.

4. Performance Curve Analysis

The datasheet references typical electrical/optical characteristics curves. While the specific graphs are not provided in the text excerpt, standard curves for such devices typically include:

• Forward Current vs. Forward Voltage (I-V Curve): Shows the exponential relationship. The curve will indicate the typical V_F of ~2.6V at 20mA and how it varies with temperature.
• Luminous Intensity vs. Forward Current: Demonstrates that light output is approximately proportional to forward current, up to the maximum ratings. It highlights the point of diminishing returns or saturation.
• Luminous Intensity vs. Ambient Temperature: Shows how light output decreases as the junction temperature of the LED increases. This is critical for designing in high-temperature environments.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~565nm and the half-width of ~30nm, defining the green color characteristics.

These curves are essential for understanding the device's behavior under non-standard conditions and for optimizing drive circuitry for efficiency and longevity.

5. Mechanical and Package Information

5.1 Package Dimensions

The display has a standard dual-digit seven-segment footprint. All critical dimensions for PCB (Printed Circuit Board) layout and mechanical integration are provided in a detailed drawing on page 3 of the datasheet. Key notes include that all dimensions are in millimeters, with standard tolerances of ±0.25 mm unless otherwise specified. Designers must refer to this drawing for exact pin spacing, overall package length, width, height, and digit center-to-center distance.

5.2 Internal Circuit Diagram and Pin Connection

The internal circuit diagram shows the common anode configuration. Each of the two digits has its own common anode pin (pin 14 for Digit 1, pin 13 for Digit 2). The cathodes for each segment (A through G, plus Decimal Point DP) are connected to individual pins, with some sharing between digits for segments in the same physical position (e.g., pin 1 is cathode E for Digit 1, pin 5 is cathode E for Digit 2).

The pin connection table provides a complete mapping of the 18-pin DIP (Dual In-line Package) interface:

• Pins 1-4, 15-18: Control segments and decimal point for Digit 1.
• Pins 5-13: Control segments, decimal point, and the common anode for Digit 2.
• Pin 14: Common anode for Digit 1.

This pinout is crucial for designing the PCB layout and writing the microcontroller firmware to drive the display correctly, typically using a multiplexing technique where the anodes are switched sequentially.

6. Soldering, Assembly, and Storage Guidelines

6.1 Soldering and Application Cautions

The datasheet provides extensive application notes to ensure reliable operation:

• Drive Circuit Design: Constant current driving is recommended over constant voltage to ensure consistent luminous intensity regardless of V_F variations. The circuit must be designed to accommodate the full V_F range (2.1V-2.6V).
• Protection: The driving circuit should incorporate protection against reverse voltages and transient voltage spikes during power-up/down sequences, as these can damage the LEDs.
• Thermal Management: The operating current must be derated based on the maximum ambient temperature to prevent excessive junction temperature, which causes rapid light degradation (lumen depreciation) and can lead to premature failure.
• Mechanical Handling: Avoid applying abnormal force to the display body during assembly. Do not let the front pattern film come into direct, tight contact with a front panel/cover, as external force may shift the film.
• Environmental: Avoid rapid temperature changes in high-humidity environments to prevent condensation on the display.

6.2 Storage Conditions

Proper storage is vital to prevent oxidation of the tin-plated leads:

• For LED Displays (Through-Hole): Store in original packaging at 5°C to 30°C with relative humidity below 60% RH. Long-term storage of large inventories is discouraged.
• For SMD LED Displays (General Note): If in a factory-sealed moisture barrier bag, store at 5°C-30°C, <60% RH. Once opened, the devices should be used within 168 hours (1 week) if stored under the same conditions, corresponding to a Moisture Sensitivity Level (MSL) of 3.

Failure to observe these conditions may necessitate re-plating of oxidized pins before use in production.

7. Application Suggestions and Design Considerations

7.1 Typical Application Scenarios

The LTD-6410G is suited for any application requiring a clear, reliable, two-digit numeric readout. This includes:

• Digital multimeters, oscilloscopes, and power supplies.
• Industrial process controllers and timers.
• Fitness equipment displays.
• Appliance control panels (ovens, microwaves).
• Retail equipment like scales or cash registers.

The datasheet specifies it is for \"ordinary electronic equipment\" and consultation is required for safety-critical applications (aviation, medical, transportation).

7.2 Design Considerations

• Current Limiting Resistors: Essential for each segment or common anode when using a voltage source. Calculate based on supply voltage, LED V_F, and desired I_F.
• Multiplexing Driver: A microcontroller with sufficient I/O pins or a dedicated display driver IC (like a MAX7219) is typically used to sequentially power each digit's common anode while activating the corresponding segment cathodes. This reduces the number of required control lines from 15 (7 segments + DP per digit, plus 2 anodes) to just 9 (7 segments + DP + 2 digit select lines).
• Refresh Rate: The multiplexing frequency must be high enough (>60 Hz) to avoid visible flicker.
• Power Supply: Must be capable of supplying the peak current when multiple segments are lit simultaneously during multiplexing.

8. Technical Comparison and Differentiation

While not explicitly compared to other models, the LTD-6410G's key differentiators within its category are:

• Color and Contrast: The specific combination of green LEDs with a gray face/white segments offers a distinct aesthetic and high contrast ratio compared to standard red-on-black or green-on-black displays.
• Binning for Intensity: The provision of categorized luminous intensity is a feature aimed at higher-end applications where display uniformity is paramount, distinguishing it from non-binned, lower-cost alternatives.
• Dual Technology Chips: The use of either GaP or AlInGaP chips allows the manufacturer to optimize for performance or cost, potentially offering benefits in efficiency or color purity compared to displays using only one technology.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive this display with a 5V microcontroller pin directly?
A: No. The typical forward voltage is 2.6V, but a current-limiting resistor is always required to set the correct forward current (e.g., 10-20mA). Connecting directly to 5V would cause excessive current and destroy the LED segment.

Q: What is the difference between peak wavelength (565nm) and dominant wavelength (569nm)?
A: Peak wavelength is the literal highest point on the spectral output curve. Dominant wavelength is a calculated value that represents the perceived color. For a monochromatic green LED, they are often close, as seen here.

Q: The maximum continuous current is 25mA, but the test condition for V_F uses 20mA. Which should I use?
A: 20mA is a common standard test condition. You can design your circuit for any forward current between the minimum needed for sufficient brightness and the maximum rated 25mA (derated for temperature). 10-20mA is a typical operating range.

Q: Why is reverse voltage rating important if I should never apply it?
A: The rating indicates the device's ability to withstand accidental reverse connection or voltage transients without immediate failure. The circuit should include protection (like a diode in parallel) to clamp any reverse voltage below 5V.

10. Practical Design and Usage Case

Case: Designing a Simple Two-Digit Counter.
A designer needs a display for a event counter. They select the LTD-6410G for its clarity and green color. They use a microcontroller with 10 I/O pins. Eight pins are configured as outputs to drive the segment cathodes (A-G, DP) via 150Ω current-limiting resistors (calculated for a 5V supply, ~2.6V V_F, and ~16mA I_F). Two additional pins are used as digit select outputs, each connected to the common anode of a digit through a small NPN transistor (e.g., 2N3904) to sink the higher cumulative current of a fully lit digit (up to 8 segments * 16mA = 128mA). The firmware implements multiplexing: it turns on the transistor for Digit 1, sets the segment pattern for the first digit's value, waits 5ms, turns off Digit 1, turns on Digit 2, sets the segment pattern for the second digit, waits 5ms, and repeats. This creates a stable, flicker-free display. The designer also adds a 1N4148 diode in parallel with each common anode line (cathode to Vcc) to protect against inductive voltage spikes when the transistors switch off.