LTC-2723JF 7-Segment LED Display Datasheet - 0.28-inch Digit Height - Yellow Orange Color - 2.6V Forward Voltage - English Technical Documentation

1. Product Overview

The LTC-2723JF is a high-performance, quadruple-digit, seven-segment alphanumeric display module. Its primary function is to provide clear, bright numerical and limited alphanumeric readouts in a wide range of electronic equipment. The core application is in devices requiring a compact, multi-digit numeric display with excellent visibility, such as test and measurement instruments, industrial control panels, point-of-sale terminals, and consumer electronics.

The device's key positioning lies in its balance of size, brightness, and power efficiency. With a 0.28-inch (7 mm) digit height, it offers a legible display without occupying excessive panel space. The use of AlInGaP (Aluminum Indium Gallium Phosphide) LED technology is a significant advantage, providing superior luminous efficiency and a distinctive, saturated yellow-orange color compared to older technologies like standard GaAsP LEDs. This results in the core benefits of high brightness, excellent contrast, and a wide viewing angle, ensuring readability even in brightly lit environments or from oblique angles.

The target market includes designers and engineers of embedded systems, instrumentation, and industrial hardware who require a reliable, easy-to-interface display solution. Its multiplexed common cathode design simplifies the driving circuitry, reducing the number of required microcontroller I/O pins and external components, which is a critical advantage for cost-sensitive and space-constrained applications.

2. In-Depth Technical Parameter Analysis

2.1 Photometric and Optical Characteristics

The optical performance is defined at an ambient temperature (T_A) of 25\u00b0C. The primary metric is the Average Luminous Intensity (I_V), which has a typical value of 600 \u00b5cd (microcandelas) when driven at a forward current (I_F) of 1 mA per segment. The specification provides a range from a minimum of 200 \u00b5cd to a maximum, ensuring a baseline level of brightness. This intensity is measured using a sensor and filter calibrated to the CIE photopic luminosity function, which approximates the human eye's spectral sensitivity.

The color characteristics are defined by wavelength parameters. The Peak Emission Wavelength (λ_p) is typically 611 nm, which falls within the yellow-orange region of the visible spectrum. The Dominant Wavelength (λ_d), a more perceptually relevant measure of color, is typically 605 nm. The Spectral Line Half-Width (Δλ) of 17 nm indicates a relatively narrow emission band, contributing to the purity and saturation of the yellow-orange color. The Luminous Intensity Matching Ratio (I_V-m) is specified as 2:1 maximum, meaning the brightness difference between segments should not exceed a factor of two, ensuring uniform appearance across the display.

2.2 Electrical and Thermal Parameters

The electrical characteristics are crucial for circuit design. The Forward Voltage per Segment (V_F) is typically 2.6V at a standard test current of 20 mA. The minimum is listed as 2.05V. This parameter is essential for calculating current-limiting resistor values and power supply requirements. The Reverse Current per Segment (I_R) is a maximum of 100 \u00b5A at a Reverse Voltage (V_R) of 5V, indicating the device's leakage characteristics in the off-state.

The Absolute Maximum Ratings define the operational limits. The Continuous Forward Current per Segment is rated at 25 mA, but this must be derated linearly above 25\u00b0C at a rate of 0.33 mA/\u00b0C. For pulsed operation, a Peak Forward Current of 60 mA is allowed under specific conditions (1/10 duty cycle, 0.1 ms pulse width). The maximum Power Dissipation per Segment is 70 mW. The device is rated for an Operating and Storage Temperature Range of -35\u00b0C to +85\u00b0C, making it suitable for industrial and extended environmental applications. The solder temperature rating specifies that the device can withstand 260\u00b0C for 3 seconds at a distance of 1/16 inch (approximately 1.6 mm) below the seating plane, which is critical information for PCB assembly processes.

3. Binning and Categorization System

The datasheet explicitly states that the device is "Categorized for Luminous Intensity." This indicates a production binning process where units are sorted based on their measured light output at a standard test condition (likely I_F=1mA). While the specific bin codes are not detailed in this excerpt, such a system allows purchasers to select parts with guaranteed minimum brightness levels, ensuring consistency in the visual appearance of final products, especially when multiple displays are used side-by-side. This categorization is a key quality control and differentiation feature.

4. Performance Curve Analysis

The datasheet includes a section for "Typical Electrical / Optical Characteristic Curves." Although the specific curves are not rendered in the provided text, standard curves for such devices typically include:

• Forward Current vs. Forward Voltage (I_F-V_F Curve): This non-linear relationship shows how voltage increases with current. It is vital for designing the driver circuit to ensure the LED operates within its safe and efficient region.
• Luminous Intensity vs. Forward Current (I_V-I_F Curve): This curve demonstrates the light output's dependence on drive current. It is generally linear over a range but will saturate at higher currents. This informs decisions about driving the display for optimal brightness versus power consumption and longevity.
• Luminous Intensity vs. Ambient Temperature: This curve shows how light output decreases as the junction temperature of the LED increases. Understanding this derating is critical for applications operating at high ambient temperatures.
• Spectral Distribution: A graph showing the relative intensity of light emitted across different wavelengths, centered around the 611 nm peak, illustrating the color purity.

5. Mechanical and Package Information

The device comes in a standard LED display package. The "Package Dimensions" section provides the mechanical outline drawing, though the specific millimeter dimensions are not listed in the text excerpt. The note specifies that all dimensions are in millimeters with tolerances of \u00b10.25 mm unless otherwise stated. This drawing is essential for PCB footprint design, ensuring the cutout in the front panel is correctly sized, and that the pins align with the PCB pads.

The package features a "gray face and white segment" appearance, which enhances contrast by reducing reflections from the non-illuminated areas (the face) while providing a clean, diffusing surface for the illuminated segments. The right-hand decimal point is integrated into the package. Polarity is clearly defined by the pinout and the common cathode architecture.

The datasheet explicitly states that the device is "Categorized for Luminous Intensity." This indicates a production binning process where units are sorted based on their measured light output at a standard test condition (likely IF=1mA). While the specific bin codes are not detailed in this excerpt, such a system allows purchasers to select parts with guaranteed minimum brightness levels, ensuring consistency in the visual appearance of final products, especially when multiple displays are used side-by-side. This categorization is a key quality control and differentiation feature.

The LTC-2723JF uses a multiplexed common cathode configuration. This is a critical design aspect. The internal circuit diagram (referenced but not shown) would reveal that each of the four digits shares its cathode connection. The anodes for corresponding segments (A, B, C, D, E, F, G, DP) across all digits are connected together internally.

The detailed pin connection is as follows: Pin 1 is the Common Cathode for Digit 1, Pin 8 for Digit 4, Pin 11 for Digit 3, and Pin 14 for Digit 2. Pin 12 is a special Common Cathode for the lower-left, lower-center, and lower-right colon segments (L1, L2, L3), which are likely used for time separation (e.g., 12:34). The segment anodes are distributed across other pins (e.g., Pin 13 for Anode A and L1, Pin 15 for Anode B and L2, Pin 2 for Anode C and L3, Pin 3 for DP, etc.). Pins 4, 9, and 10 are marked as "No Connection" or "No Pin." This pinout must be followed precisely for the multiplexing scheme to work correctly.

7. Soldering and Assembly Guidelines

The primary assembly guideline provided is the soldering temperature specification: the device can withstand 260\u00b0C for 3 seconds at a point 1/16 inch (1.6 mm) below the seating plane. This is a standard rating for wave soldering or reflow soldering processes. Designers must ensure their PCB assembly profile does not exceed this thermal stress. For manual soldering, a temperature-controlled iron should be used with minimal contact time per pin.

General handling precautions for LEDs apply: avoid mechanical stress on the epoxy lens, protect from electrostatic discharge (ESD) during handling, and store in appropriate anti-static, moisture-controlled environments if not used immediately after opening the sealed packaging.

8. Application Design Considerations

8.1 Typical Application Circuits

The most common application is driven by a microcontroller. Due to the multiplexed common cathode design, the microcontroller must use a scanning technique. It sets the pattern for a single digit on the common anode lines (segments A-G, DP) and then activates (sinks current to ground) the corresponding common cathode pin for that digit. After a short period (e.g., 1-5 ms), it moves to the next digit, cycling through all four digits rapidly. The human eye perceives this as a continuously lit display due to persistence of vision. This method reduces the required I/O pins from (7 segments + 1 DP) * 4 digits = 32 pins down to 7 segment pins + 4 digit pins + 3 colon pins = 14 pins, a significant saving.

External components typically include current-limiting resistors in series with each segment anode line. The resistor value is calculated using Ohm's Law: R = (V_supply - V_F) / I_FFor a 5V supply, a typical V_F of 2.6V, and a desired I_F of 10 mA, the resistor would be (5 - 2.6) / 0.01 = 240 Ohms. Since the display is multiplexed, the instantaneous current during each digit's active time can be higher to achieve the same average brightness; for example, driving at 40 mA peak during a 25% duty cycle yields an average of 10 mA.

8.2 Design Notes and Best Practices

• Driver Selection: Ensure the microcontroller or dedicated driver IC can sink enough current for the common cathode pins (the sum of currents for all lit segments in one digit).
• Refresh Rate: Hana a cika wutar lantarki sama da 60 Hz don guje wa fitilar da ake iya gani. Tare da lambobi 4, lokacin binciken kowane lamba ya kamata ya kasance ƙasa da ~4 ms.
• Sarrafa Haske: Ana iya sarrafa haske cikin sauƙi a cikin software ta hanyar daidaita lokacin aiki na haɗakarwa ko ƙarfin tuƙi mafi girma (a cikin iyakoki na cikakke).
• Tsarin Wutar Lantarki: Avoid applying signals to segment anodes when no cathode is active, as this can cause undefined states and potential latch-up.
• Viewing Angle: Leverage the wide viewing angle by mounting the display perpendicular to the expected primary line of sight of the user.

9. Technical Comparison and Advantages

Compared to older red GaAsP LED displays, the AlInGaP technology in the LTC-2723JF offers significantly higher luminous efficiency. This means it produces more light (higher candela output) for the same electrical input current, leading to lower power consumption for a given brightness or higher maximum brightness. The yellow-orange color (605-611 nm) is often subjectively perceived as brighter and more attention-grabbing than standard red, and it may offer better performance in environments with ambient red light.

Compared to larger digit displays, the 0.28-inch size offers a compact footprint ideal for portable or densely packed instruments. Compared to liquid crystal displays (LCDs), this LED display offers superior brightness, wider viewing angles, and faster response times, and it does not require a backlight, simplifying the design. Its main trade-off is higher power consumption than an LCD, especially when multiple segments are illuminated.

10. Frequently Asked Questions (FAQ)

Q: How do I calculate the correct current-limiting resistor value?
A: Use the formula R = (V_CC - V_F) / I_F. Use the typical V_F from the datasheet (2.6V) for initial calculation. Choose an I_F based on your desired brightness, staying below the 25 mA continuous maximum. Remember this is per segment. For a multiplexed design, the instantaneous I_F will be higher to achieve the same average brightness.

Q: Ina iya tuƙa wannan nuni da ƙayyadaddun ƙarfi (wanda ba a haɗa shi da yawa ba)?
A: A fasaha a'a, ta hanyar haɗa kowane lamba ta cathode daban zuwa ƙasa da tuƙa sassan kai tsaye. Duk da haka, wannan yana buƙatar ƙarin filaye na I/O (32+) kuma ba shi da inganci dangane da albarkatun microcontroller da amfani da wutar lantarki. Ƙirar da aka haɗa da yawa shine yanayin da aka yi niyya kuma mafi kyau.

Q: Menene manufar "Luminous Intensity Matching Ratio"?
A: O le fua faatatau 2:1 e mautinoa ai le tutusa o le vaʻaia. E faʻamautinoa ai e leai se vaega i totonu o se masini e sili atu i le faaluaina le malamalama nai lo soʻo se isi vaega pe a faʻauluina i lalo o tulaga tutusa. O lenei mea e taofia ai nisi numera poʻo vaega mai le faʻaalia manino o le faanenefu pe susulu, lea o le a faʻalavelaveina le vaʻaia.

Q: E manaʻomia se faʻamalo vevela?
A: Mo le faʻagaioiga masani i totonu o tapulaʻa faʻamaonia o le taimi nei ma le vevela, e le manaʻomia se faʻamalo vevela. O le 70 mW maualuga maualuga o le faʻamavaeina o le mana i le vaega e faigofie ona pulea e le afifi o le masini ma le PCB i lalo o tulaga masani. Ia mautinoa le lelei o le ea pe a faʻagaoioia i le maualuga o le vevela o le siʻosiʻomaga e latalata i le maualuga maualuga.

11. Practical Design and Usage Example

Scenario: Designing a Digital Multimeter Readout. The LTC-2723JF is an excellent choice for a 4-digit multimeter display. The design would involve a microcontroller with an analog-to-digital converter (ADC) measuring voltage, current, or resistance. The microcontroller processes the reading and converts it into the appropriate 7-segment codes for the four digits, handling the decimal point position based on the range.

The firmware implements a timer interrupt to manage the multiplexing scan. Four microcontroller pins are configured as open-drain or strong sink outputs connected to the four digit cathodes (Pins 1, 14, 11, 8). Seven other pins are configured as push-pull outputs connected through 180-ohm current-limiting resistors to the segment anodes (A, B, C, D, E, F, G). The DP anode (Pin 3) would be connected to an eighth pin if needed.

Every 2.5 ms (for a 100 Hz total refresh rate), the timer interrupt fires. The firmware turns off all digit cathodes, updates the segment anode outputs to display the pattern for the next digit in sequence, and then activates only that digit's cathode pin. This process repeats continuously. The yellow-orange color provides high contrast against the gray face, ensuring readability in various lighting conditions encountered by a handheld meter.

12. Operating Principle

The fundamental principle is electroluminescence in a semiconductor P-N junction. The AlInGaP (Aluminum Indium Gallium Phosphide) material is a direct bandgap semiconductor. When forward-biased (positive voltage on the anode relative to the cathode), electrons from the N-type region and holes from the P-type region are injected into the active region. When these charge carriers recombine, they release energy in the form of photons (light). The specific composition of the AlInGaP alloy determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light—in this case, yellow-orange (~605-611 nm). The gray face and white segment material act as a diffuser and contrast enhancer, shaping and directing the light from the tiny LED chips into the recognizable segments.

13. Technology Trends and Context

AlInGaP LED technology represents a significant advancement over earlier LED materials like GaAsP (Gallium Arsenide Phosphide) for red, orange, and yellow colors. It offers vastly superior internal quantum efficiency and temperature stability, meaning more electrical energy is converted to light and brightness is maintained better over a wide temperature range. This technology enabled the development of high-brightness, high-efficiency LEDs suitable for outdoor and automotive applications long before the widespread adoption of high-power white LEDs.

Duk da yanzu na'urorin nuni sukan yi amfani da OLEDs na dot-matrix ko TFT LCDs don cikakken zane-zane, nuni na LED mai sassa bakwai yana ci gaba da kasancewa mai mahimmanci saboda sauƙinsa na musamman, ƙarfi, arha, da kuma dacewa sosai don karatun lambobi kawai. Ci gabansa yana mai da hankali kan haɓaka inganci (lumens a kowace watt), inganta ma'auni (dukansu fuska masu duhu, sassa masu haske), da ba da nau'ikan girma da launuka iri-iri a cikin tsarin kayan AlInGaP da InGaN (don shuɗi/kore/fari). Dabarar multiplexing da ake amfani da ita a cikin na'urori kamar LTC-2723JF wata hanya ce ta gargajiya kuma mai dorewa don magance matsalar sarrafa abubuwa masu nuni da yawa tare da ƙayyadaddun layukan sarrafawa.