LTC-2623KF-J LED Display Datasheet - 0.28-inch Digit Height - Yellow Orange Color - 2.6V Forward Voltage - English Technical Document

1. Product Overview

The LTC-2623KF-J is a high-performance, quadruple-digit, seven-segment display module designed for applications requiring clear, bright numeric readouts. Its primary function is to present numerical data in a highly legible format. The core advantage of this device lies in its use of advanced AlInGaP (Aluminum Indium Gallium Phosphide) LED technology, which provides superior luminous efficiency and color purity compared to traditional materials. This makes it particularly suitable for instrumentation panels, industrial control systems, test equipment, and consumer electronics where readability under various lighting conditions is critical. The target market includes designers and engineers in the industrial automation, automotive dashboard, medical device, and point-of-sale terminal sectors who require reliable, long-lasting, and energy-efficient display solutions.

2. In-Depth Technical Parameter Analysis

2.1 Optical and Electrical Characteristics

The performance of the LTC-2623KF-J is defined by several key parameters measured under standard conditions (Ta=25°C).

• Luminous Intensity (I_V): The typical average luminous intensity is 1200 µcd at a forward current (I_F) of 1mA, with a specified range from 500 µcd (Min) to the typical value. This high brightness level ensures excellent visibility. The luminous intensity matching ratio between segments is specified at a maximum of 2:1, ensuring uniform appearance across the display.
• Spectral Characteristics: The device emits light in the yellow-orange spectrum. The peak emission wavelength (λ_p) is typically 611 nm at I_F=20mA. The dominant wavelength (λ_d) is 605 nm, and the spectral line half-width (Δλ) is 17 nm, indicating a relatively pure and saturated color output.
• Electrical Parameters: The forward voltage (V_F) per segment is typically 2.6V, with a maximum of 2.6V at I_F=20mA. The reverse current (I_R) is a maximum of 100 µA at a reverse voltage (V_R) of 5V. It is crucial to note that the reverse voltage rating is for leakage current testing only; the device is not intended for continuous operation under reverse bias.

2.2 Absolute Maximum Ratings and Thermal Considerations

Operating the device beyond these limits may cause permanent damage.

• Power Dissipation: The maximum power dissipation per segment is 70 mW.
• Current Ratings: The continuous forward current per segment is 25 mA. A derating factor of 0.33 mA/°C applies linearly from 25°C. The peak forward current per segment (for pulsed operation at 1kHz, 10% duty cycle) is 60 mA.
• Temperature Range: The device can operate within an ambient temperature range of -35°C to +85°C. The storage temperature range is identical.
• Solderability: The device can withstand a soldering temperature of 260°C for 3 seconds at a distance of 1/16 inch (approximately 1.6 mm) below the seating plane.

3. Binning System Explanation

The datasheet explicitly states that the device is "BINNED FOR LUMINOUS INTENSITY." This means the LEDs are sorted (binned) during manufacturing based on their measured light output at a specific test current. This process ensures consistency within a production lot. Customers receive devices with luminous intensity falling within the specified minimum and typical ranges (500-1200 µcd @ 1mA). While not explicitly detailed for wavelength/color or forward voltage in this specific datasheet, such binning is common practice in the industry to provide predictable performance. Designers should consult the manufacturer for specific binning details if tight color or voltage matching is required for their application.

4. Performance Curve Analysis

The datasheet references "TYPICAL ELECTRICAL / OPTICAL CHARACTERISTIC CURVES." Although the specific graphs are not provided in the text, typical curves for such a device would include:

• I-V (Current-Voltage) Curve: This graph would show the relationship between forward current and forward voltage, typically exhibiting an exponential rise after the turn-on voltage (~2.0-2.2V for AlInGaP). It is essential for designing the current-limiting circuitry.
• Luminous Intensity vs. Forward Current: This curve shows how light output increases with current. It is generally linear over a range but will saturate at higher currents due to thermal effects.
• Luminous Intensity vs. Ambient Temperature: This graph illustrates the decrease in light output as the junction temperature rises. AlInGaP LEDs typically have a negative temperature coefficient for luminous intensity.
• Spectral Distribution: A plot of relative intensity versus wavelength, showing the peak at ~611 nm and the 17 nm half-width.

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

5. Mechanical and Package Information

5.1 Physical Dimensions

The device features a 0.28-inch (7.0 mm) digit height. The package dimensions are provided in a drawing (not fully detailed in text), with all dimensions in millimeters and standard tolerances of ±0.25 mm unless otherwise noted. The display has a gray face with white segments, enhancing contrast.

5.2 Pin Configuration and Circuit Diagram

The LTC-2623KF-J is a multiplexed common anode display. This means the anodes of the LEDs for each digit are connected together internally, while the cathodes for each segment (A-G, DP, and colon segments L1, L2, L3) are shared across digits. This configuration reduces the number of required driver pins from 32 (4 digits * 8 segments) to 16. An internal circuit diagram would show this multiplexing arrangement. The pin connection table is provided:

• Pin 1: Common Anode for Digit 1
• Pin 2: Cathode for segments C and L3 (lower colon dot)
• Pin 3: Cathode for Decimal Point (DP)
• Pin 5: Cathode for segment E
• Pin 6: Cathode for segment D
• Pin 7: Cathode for segment G
• Pin 8: Common Anode for Digit 4
• Pin 11: Common Anode for Digit 3
• Pin 12: Common Anode for colon segments L1 and L2 (upper colon dots)
• Pin 13: Cathode for segments A and L1
• Pin 14: Common Anode for Digit 2
• Pin 15: Cathode for segments B and L2
• Pin 16: Cathode for segment F
• Pins 4, 9, 10: No Connection

6. Soldering and Assembly Guidelines

The key assembly specification is the solder temperature profile: the device can withstand 260°C for 3 seconds at a point 1/16 inch (1.6 mm) below the seating plane. This is a standard reflow soldering condition. Designers must ensure their PCB layout and reflow oven profile comply with this to prevent thermal damage to the LED chips or the plastic package. It is recommended to follow standard JEDEC/IPC guidelines for moisture sensitivity and baking if the devices have been exposed to humid environments before soldering. Storage should be within the specified -35°C to +85°C range in a dry, anti-static environment.

7. Packaging and Ordering Information

The part number is LTC-2623KF-J. The "KF" suffix typically indicates the package style and color (gray face, white segments). The "J" may denote a specific bin or revision. While specific packaging details (reel, tube, tray) are not listed in the provided text, such displays are commonly supplied in anti-static tubes or trays to protect the pins and lens. The ordering code directly corresponds to the device description: AlInGaP Yellow Orange, Multiplex Common Anode, with a right-hand decimal point.

8. Application Recommendations

8.1 Typical Application Scenarios

This display is ideal for any application requiring a bright, multi-digit numeric readout. Examples include digital multimeters, frequency counters, process timers, weighing scales, automotive dashboard gauges (e.g., clock, odometer), and industrial control panel indicators.

8.2 Design Considerations

• Drive Circuitry: A multiplexed display requires a driver IC or microcontroller capable of sinking sufficient segment current and sourcing digit anode current. The driver must cycle through the digits at a high enough frequency (typically >100Hz) to avoid visible flicker.
• Current Limiting: External current-limiting resistors are mandatory for each segment cathode or a constant-current driver should be used to prevent exceeding the maximum continuous forward current, especially important given the derating above 25°C.
• Viewing Angle: The datasheet mentions a "wide viewing angle," which is characteristic of LED seven-segment displays. PCB placement should consider the intended viewer's position.
• Power Sequencing: Ensure the drive electronics do not apply reverse voltage or excessive current spikes during power-up or power-down.

9. Technical Comparison and Differentiation

The primary differentiating factors of the LTC-2623KF-J are its use of AlInGaP semiconductor material and its specific mechanical format. Compared to older GaAsP or GaP LEDs, AlInGaP offers significantly higher luminous efficiency, resulting in brighter displays at lower currents. Compared to very small SMD seven-segment displays, the 0.28-inch digit height provides excellent long-distance readability. Compared to LCDs, it offers superior brightness, wider viewing angles, and better performance in extreme temperatures, though at the cost of higher power consumption. The multiplexed common anode design is a standard approach that optimizes the pin count for this digit size.

10. Frequently Asked Questions (Based on Technical Parameters)

Q: What is the purpose of the luminous intensity binning?
A: Binning ensures visual consistency across all digits and segments in your product. It guarantees that the brightness variation between any two segments or devices from the same order will not exceed a 2:1 ratio.

Q: Can I drive this display with a 5V microcontroller directly?
A: No. The typical forward voltage is 2.6V. Connecting a 5V source directly would destroy the LED due to excessive current. You must use a series current-limiting resistor or a constant-current driver. The resistor value depends on your supply voltage and desired segment current.

Q: What does "multiplexed common anode" mean for my driver circuit?
A: You cannot light all digits simultaneously at full brightness. You must sequentially turn on (source current to) one digit's common anode at a time while sinking current to the desired segments for that digit. This is done rapidly to create the illusion of all digits being on constantly.

Q: Is the reverse voltage rating of 5V for normal operation?
A: No. The datasheet explicitly states it is only for the I_R (reverse current) test. The display should never be subjected to a continuous reverse bias in application. Proper circuit design should prevent this.

11. Practical Design and Usage Case

Case: Designing a 4-Digit Voltmeter Readout. A designer is creating a benchtop power supply unit that requires a bright, clear output voltage display. They select the LTC-2623KF-J for its 0.28-inch digit height and high contrast. The microcontroller's ADC reads the output voltage. The firmware converts this value to BCD format. A dedicated display driver IC (like the MAX7219) is chosen to handle the multiplexing. The designer calculates the current-limiting resistor value for a segment current of 10mA using the formula R = (V_supply - V_F) / I_F. With a 5V supply and V_F=2.6V, R = (5 - 2.6) / 0.01 = 240 ohms. A 220-ohm standard resistor is selected, resulting in a slightly higher current (~10.9mA), which is still well within the 25mA continuous rating. The multiplexing frequency is set to 250Hz to eliminate flicker. The gray face of the display is chosen to match the instrument's bezel color, providing a professional integrated look.

12. Technical Principle Introduction

The LTC-2623KF-J is based on AlInGaP semiconductor technology grown on a GaAs substrate. When a forward voltage exceeding the bandgap energy is applied across the p-n junction of the LED chip, electrons and holes recombine, releasing energy in the form of photons (light). The specific composition of Aluminum, Indium, Gallium, and Phosphide in the active layer determines the bandgap energy, which directly corresponds to the wavelength (color) of the emitted light—in this case, yellow-orange (~605-611 nm). The seven-segment format is created by placing multiple tiny LED chips (one per segment per digit) in the pattern of a standard digit and connecting them internally in the multiplexed common anode configuration described earlier. The gray face and white segment diffusers enhance contrast by absorbing ambient light and efficiently scattering the emitted light from the LED chips.

13. Technology Trends

While traditional through-hole seven-segment LED displays like the LTC-2623KF-J remain vital for many applications due to their robustness and high brightness, the general trend in display technology is moving towards surface-mount device (SMD) packages and higher integration. SMD seven-segment displays offer smaller footprints and are better suited for automated assembly. Furthermore, there is a growing shift towards dot-matrix displays and fully integrated graphic OLED or TFT modules that offer alphanumeric and graphical capability in a similar space. However, for dedicated numeric readouts where extreme brightness, simplicity, reliability, and cost-effectiveness are paramount, discrete seven-segment LED displays continue to be a preferred solution. Advances in materials like AlInGaP have significantly improved their efficiency and color range, ensuring their relevance in specific market segments.