LTC-5675KG LED Digital Tube Datasheet - 0.52-Inch Character Height - AlInGaP Green - 2.6V Forward Voltage - Technical Documentation

1. Product Overview

LTC-5675KG ni moduli ya kuonyesha yenye sehemu saba za tarakimu nne. Kazi yake kuu ni kutoa taarifa za nambari na herufi chache zilizo wazi na zinazoonekana vyema katika vifaa mbalimbali vya elektroniki na vyombo vya kupimia. Teknolojia yake ya msingi inatumia chip ya LED ya AlInGaP (aluminium-indium-gallium-phosphide), ambayo imewekwa kwenye msingi usio na uwazi wa GaAs, na inajulikana kwa kutoa mwanga wa kijani wenye ufanisi mkubwa. Kionyeshi hiki kina muundo wa paneli ya kijivu na alama nyeupe za sehemu, ikitoa tofauti bora kwa sehemu zinazong'aa za kijani. Muundo huu unalenga hasa matumizi yanayohitaji kuonyesha nambari thabiti, zenye nguvu chini na utendaji bora wa kuona, kama vile paneli za udhibiti wa viwanda, vifaa vya kupimia, vifaa vya matumizi ya kaya na vyombo vinavyohitaji kuonyesha nambari nyingi zenye ukubwa mdogo.

1.1 Key Features and Advantages

• Digit Size:0.52 inches (13.2 mm) character height, providing good readability.
• Segment design:Continuous uniform segments ensure a beautiful character appearance.
• Optical performance:High brightness and high contrast, ensuring clear visibility under various lighting conditions.
• Viewing Angle:Wide viewing angle, ensuring clear readability of the displayed content even from off-axis positions.
• Energy Efficiency:Low power consumption requirements, suitable for battery-powered or energy-conscious applications.
• Reliability:Solid-state reliability, no moving parts, long service life.
• Quality Control:Devices are graded by luminous intensity to ensure uniform brightness matching in multi-digit or multi-unit applications.
• Environmental Compliance:Lead-free packaging, compliant with the RoHS (Restriction of Hazardous Substances) directive.

2. Detailed Technical Specifications

This section provides a detailed and objective analysis of the electrical and optical parameters specified in the datasheet.

2.1 Absolute Maximum Ratings

These ratings define the stress limits that may cause permanent damage to the device. Operation outside these ranges is not recommended.

• Power consumption per segment:Maximum 70 mW. This limits the maximum continuous current based on forward voltage.
• Peak forward current per segment:Maximum 60 mA, but only under pulse conditions (1 kHz, 25% duty cycle). This rating applies to multiplexed or brief surge conditions.
• Continuous forward current per segment:Maximum 25 mA at 25°C. This current derates linearly at 0.33 mA/°C when the ambient temperature exceeds 25°C. For example, at 85°C, the maximum allowable continuous current is approximately: 25 mA - ((85°C - 25°C) * 0.33 mA/°C) = 5.2 mA.
• Reverse voltage per segment:Maximum 5 V. Exceeding this value may cause junction breakdown.
• Operating temperature range:-35°C to +85°C. This device is suitable for the industrial temperature range.
• Temperature Range for Storage:-35°C to +85°C.
• Soldering Conditions:260°C for 3 seconds, specified that this temperature is measured 1/16 inch (approximately 1.6 mm) below the component mounting plane. This is a typical reflow soldering profile guideline.

2.2 Electrical and Optical Characteristics (Ta=25°C)

These are typical operating parameters under specified test conditions.

• Average luminous intensity (I_V):This is a key brightness parameter.
  • Minimum value: 320 µcd at I_F= 1 mA
  • Typical value: 1050 µcd at I_F= 10 mA
  • Maximum value: 11550 µcd at I_F= 10 mA. The wide range from minimum to maximum indicates that the devices are graded (binned). Designers must select from the appropriate grade to ensure uniform brightness.
• Peak emission wavelength (λ_p):In I_F=20mA, it is 571 nm (typical value). This is located in the green region of the visible spectrum.
• Spectral line half-width (Δλ):15 nm (typical value). This indicates the spectral purity or bandwidth of the emitted green light.
• Dominant wavelength (λ_d):572 nm (typical). Slightly different from peak wavelength, this is the wavelength of monochromatic light that the human eye perceives as matching the color of the light source.
• Forward voltage per segment (V_F):In I_F=2.1V (min), 2.6V (typical) at 20mA. This is crucial for designing current-limiting circuits. The drive circuit must provide sufficient voltage to overcome this V_F.
• Reverse current per segment (I_R):In V_R=5V maximum 100 µA. Low value indicates good junction quality.
• Luminous intensity matching ratio (I_V-m):In the "similar light zone," the maximum ratio between segments is 2:1. This means the brightest segment should not be more than twice as bright as the darkest segment within a single digit or specified group, ensuring visual uniformity.

Measurement Instructions:Luminous intensity is measured using a sensor and filter combination that simulates the CIE photopic response curve, ensuring the measured values align with human perception of brightness.

3. Explanation of the Grading System

The datasheet clearly states that the devices are "graded by luminous intensity". This is a grading process.

• Luminous intensity grading:I_VThe wide range of specifications (320 to 11550 µcd at 10mA) indicates the existence of multiple brightness grades. Manufacturers test and categorize (bin) components based on measured output. This allows customers to purchase parts with a guaranteed minimum brightness level (e.g., Grade I_V> 8000 µcd 的等级）的部件用于高亮度应用，或为标准等级用于成本敏感的设计。使用分级部件对于在多个显示器或数字之间实现外观均匀至关重要。
• Wavelength Consistency:Although not explicitly stated as a binning parameter, λ_p(571 nm) and λ_d(572 nm) has a narrow typical value range, indicating good process control, thereby ensuring consistent green color across different production batches.

4. Performance Curve Analysis

The datasheet references "Typical Electrical/Optical Characteristic Curves". Although specific charts are not provided in the text, we can infer their standard content and importance.

• Forward Current vs. Forward Voltage (I-V Curve):This graph will show an exponential relationship. It is crucial for determining the required power supply voltage for a given drive current and for calculating power dissipation (P = V_F* I_F) crucial.
• Luminous Intensity vs. Forward Current:This curve shows how brightness increases with current. It is typically nonlinear; due to heating, efficiency (lumens per watt) usually decreases at very high currents. The datasheet provides discrete points at 1mA and 10mA.
• Luminous Intensity vs. Ambient Temperature:For AlInGaP LEDs, light output typically decreases as junction temperature increases. This curve is crucial for designing applications that operate across the entire temperature range (-35°C to +85°C) to ensure sufficient brightness at high temperatures.
• Spectral Distribution:A graph showing relative intensity versus wavelength, with a center wavelength of approximately 571-572 nm and a half-width of about 15 nm, confirming the green light output.

5. Mechanical and Packaging Information

5.1 Package Dimensions

This device uses a standard LED digit package. The dimension drawing (mentioned but not detailed in the text) typically shows:

• The overall length, width, and height of the module.
• The digit spacing (pitch).
• Segment dimensions and spacing.
• Pin pitch, length, and diameter. Note: All dimensions are in millimeters, unless otherwise specified, with a general tolerance of ±0.25 mm.

5.2 Pin Configuration and Polarity

The LTC-5675KG is aCommon Anodedevice. This means the anodes of all LEDs for each digit are internally connected together and brought out to one pin per digit (pins 10-13: Digit 1-4 anodes). The cathodes for each segment (A-G, DP) are shared across all digits and connected to their respective pins (pins 27-30, 35-37 for segments A-G; pins 31-34 for decimal points). This configuration is well-suited for multiplexing.

Multiplexing operation:To display a digit, the microcontroller will:

1. Set the pattern for the segment cathodes (A-G) of the desired character.
2. Apply voltage to the common anode pin of a specific digit, and the character should appear on that digit.
3. Cycle through the anode of each digit sequentially at a high frequency (e.g., 100Hz+), creating the visual effect of all digits lighting up simultaneously. Compared to static driving, this significantly reduces the required drive pins and power consumption.

Internal circuit diagram:The referenced diagram visually confirms the common-anode, multiplexed architecture, showing four digit anodes and seven segment plus one decimal point cathodes.

6. Welding and Assembly Guide

• Reflow Soldering:The specified condition is 260°C for 3 seconds, measured 1.6 mm below the component body. This complies with the typical lead-free reflow soldering profile (peak temperature 245-260°C).
• Precautions:
  • Avoid applying mechanical stress to the pins during operation.
  • Ensure the display does not exceed the maximum storage temperature before and after soldering.
  • Follow standard ESD (Electrostatic Discharge) prevention measures during operation.
• Storage Conditions:Store in a dry environment within the specified temperature range of -35°C to +85°C to prevent moisture absorption, which may cause "popcorn" phenomenon during reflow soldering.

7. Application Recommendations

7.1 Typical Application Scenarios

• Industrial Instrumentation:Panel meters, process controllers, timer displays.
• Test and Measurement Equipment:Digital Multimeter, Frequency Counter, Power Supply.
• Consumer/Commercial Appliances:Microwave ovens, audio equipment, point-of-sale terminals.
• Automotive aftermarket:Instruments and displays requiring high brightness to ensure daytime visibility.

7.2 Design Considerations

• Current Limiting:Always use a series current-limiting resistor for each segment cathode or digital anode (depending on the drive scheme). The resistor value is calculated as R = (V_{Power Supply}- V_F) / I_F. For a 5V power supply, V_F=2.6V, and I_F=10mA: R = (5 - 2.6) / 0.01 = 240 Ω.
• Multiplexing driver:Use a microcontroller with sufficient I/O pins or a dedicated LED driver IC (e.g., MAX7219, TM1637), which can handle multiplexing and current control. The driver IC simplifies the design and often provides brightness control.
• Power consumption:Power consumption:
• Brightness Matching:For optimal visual effect, specify the luminous intensity grade to the supplier, especially when using multiple displays.
• Viewing Angle:Wide viewing angle allows flexible installation, but consider the line of sight of the primary user during mechanical design.

8. Technical Comparison and Differentiation

Compared to older technologies such as standard GaP (Gallium Phosphide) green LEDs or filtered incandescent displays, the AlInGaP technology in the LTC-5675KG provides:

• Higher efficiency and brightness:AlInGaP offers superior luminous efficiency, enabling brighter displays at lower currents.
• Better Color Saturation:Green is typically purer and more vivid.
• Higher reliability:Solid-state LEDs have a much longer lifespan than incandescent bulbs or vacuum fluorescent displays (VFD).
• Lower power consumption:Crucial for portable and battery-powered devices.
• Compared to some modern blue chip + phosphor white LEDs that generate green light through filters, AlInGaP green light is generally more efficient for monochromatic green light applications.

9. FAQ (Based on Technical Specifications)

1. Q: What is the difference between "peak wavelength" and "dominant wavelength"?
   A: Peak wavelength is the single wavelength at which the emission spectrum intensity reaches its maximum. Dominant wavelength is the wavelength of monochromatic light that matches the perceived color of a light source. They are typically close but not identical, with dominant wavelength being more relevant to human visual perception.
2. Q: Can I drive this display directly with a 3.3V microcontroller (without using a driver IC)?
   A: Possibly, but caution is required. Typical V_FAt 20mA, it is 2.6V. At 3.3V, the voltage headroom for the current-limiting resistor is only 0.7V. For a 10mA current, you need a 70Ω resistor. This is feasible, but V_Fand power supply voltage variations can cause significant current changes. Using a dedicated LED driver or transistor buffer is more robust.
3. Q: Why does continuous current derate with temperature?
   A: As the LED junction temperature increases, its internal efficiency decreases, and the risk of thermal runaway rises. Current derating prevents excessive heat generation, ensures long-term reliability, and prevents luminance degradation or failure.
4. Q: What does "grading by luminous intensity" mean for my design?
   A: This means you should work with your distributor to select a specific brightness grade (e.g., minimum I_Vvalue). If this is not done, you may receive parts from different grades, leading to noticeable brightness variations between digits or between different units of the product.

10. Design and Use Case Studies

Scenario: Design a 4-digit DC voltage panel meter.

1. Microcontroller Selection:Select an MCU with at least 12 digital I/O pins (4 digit anodes + 7 segment cathodes + 1 decimal point), or use an I/O expander.
2. Driving Circuit:Implement multiplexing in the firmware. The MCU will rapidly cycle through digits 1-4. For each digit, it sets the segment pattern on the cathode pins and enables the corresponding anode pin via a small NPN transistor (because the anode current for a fully lit digit '8' could be 8 segments * 10mA = 80mA, exceeding the limit of most MCU pins).
3. Current Limiting:Place eight 220Ω resistors (one for each segment cathode A-G and DP). With a 5V supply and typical V_F.
4. Brightness control:If needed, implement software PWM (Pulse Width Modulation) on the digit enable time to globally dim the display.
5. Result:A compact, efficient, and bright display that shows voltage readings from 0.000 to 19.99V, offering excellent readability in both indoor and outdoor lighting conditions due to its high-contrast, high-brightness AlInGaP segments.

11. Introduction to Technical Principles

LTC-5675KG is based onAlInGaP (aluminum indium gallium phosphide)semiconductor technology. This material system is epitaxially grown on anon-transparent GaAs (gallium arsenide) substrateWhen a forward voltage is applied to the p-n junction of the AlInGaP layer, electrons and holes recombine, releasing energy in the form of photons. The specific composition of Al, In, Ga, and P atoms in the active layer determines the bandgap energy, which directly dictates the wavelength (color) of the emitted light. For this device, the composition is tuned to produce green light with a central wavelength of approximately 572 nm. The opaque substrate means light is primarily emitted from the top surface of the chip, which is suitable for segment-based display structures. Individual LED chips are wire-bonded and assembled into a standard seven-segment pattern within a plastic package.

12. Technology Trends and Background

AlInGaP technology represents a mature and highly optimized solution for high-efficiency red, orange, amber, and green LEDs. In the field of displays:

• For monochrome displays:Due to its efficiency and color purity, AlInGaP remains the preferred choice for pure green, red, and amber, generally outperforming blue chip + phosphor white LEDs that generate these colors through filters.
• Market background:Although dot-matrix OLED and TFT-LCD dominate in full-color, high-information-content displays, seven-segment LED displays like the LTC-5675KG maintain a strong position in applications requiring simple, very bright, low-cost, reliable, and low-power digital readouts.
• Future Development:Trends include further improving efficiency, providing tighter brightness and color grading for high-end applications, and integrating drive electronics and communication interfaces (such as I2C) directly into the display module, thereby simplifying system design. However, the basic seven-segment form in standard colors and AlInGaP technology will likely retain their importance in their target applications for many years to come.