LTC-4627JR LED Digital Tube Datasheet - 0.4 Inch Character Height - Super Red Light - 2.6V Forward Voltage - 70mW Power Consumption - Technical Documentation

1. Product Overview

LTC-4627JR is a four-digit seven-segment character LED digital tube display module. Its main function is to provide clear, bright numeric and limited character readouts in various electronic devices. The core technology utilizes AlInGaP (aluminum indium gallium phosphide) semiconductor material to produce ultra-red light emission. This material system, grown on an opaque GaAs substrate, is renowned for its high efficiency and excellent color purity in the red light spectrum. The device features a gray panel with white segment markings, enhancing contrast and readability under various lighting conditions. It is designed as a multiplexed common anode type, which is a standard configuration for multi-digit displays, aiming to minimize the number of required drive pins.

1.1 Key Features and Advantages

• Compact and Easy to Read:With a character height of 0.4 inches (10.0 mm), it achieves a good balance between size and visibility.
• Excellent Optical Performance:Provides high brightness and high contrast, ensuring characters are clearly visible. Continuous and uniform segments offer a consistent appearance.
• Energy Efficient and High Performance:Low power consumption requirements, suitable for battery-powered applications or those prioritizing energy efficiency.
• Excellent viewing angle:Provides a wide viewing angle, allowing the display to be read from different positions.
• High reliability:Thanks to solid-state reliability, there are no moving parts or filaments to wear out.
• Quality Assurance:Devices are binned by luminous intensity to ensure consistent brightness levels within specified bins.
• Environmental Compliance:Packaged as lead-free, manufactured in compliance with the RoHS (Restriction of Hazardous Substances) directive.

1.2 Device Identification

Model LTC-4627JR specifically refers to an ultra-red, multiplexed common-anode display with a right-hand decimal point. This naming convention aids in the precise identification of the device's electrical configuration and optical characteristics.

2. Detailed Technical Specifications

2.1 Absolute Maximum Ratings

These ratings define the limits beyond which permanent damage to the device may occur. Operation should always be maintained within these boundaries.

• Power consumption per segment:Maximum 70 mW. Exceeding this value may lead to overheating and malfunction.
• Peak forward current per segment:Maximum 90 mA, but only under pulse conditions (1/10 duty cycle, 0.1ms pulse width). This applies to multiplexing or brief testing.
• Continuous forward current per segment:Maximum 25 mA at 25°C. This rating is linearly derated as ambient temperature (Ta) increases above 25°C, with a derating factor of 0.33 mA/°C. For example, at 50°C, the maximum continuous current is approximately 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Operating and Storage Temperature Range:-35°C to +85°C.
• Soldering Conditions:The device can withstand wave soldering with the solder pot 1/16 inch (≈1.6mm) below the mounting plane for 3 seconds at 260°C. The device body temperature must not exceed its maximum rating during assembly.

I-V (Current-Voltage) Curve: Shows the exponential relationship, highlighting the typical forward voltage (VF) of approximately 2.0-2.6V. Luminous Intensity vs. Forward Current Curve (IV vs. IF): Illustrates how light output increases with current up to the maximum rated limit. It helps designers choose an operating point for desired brightness and efficiency. Luminous Intensity vs. Ambient Temperature Curve: Shows the decrease in light output with increasing temperature, emphasizing the need for thermal management in high-temperature environments. Spectral Distribution Diagram: A plot of relative intensity versus wavelength, centered at 639 nm (peak) and 631 nm (dominant), with a specified 20 nm half-width.

These are the guaranteed performance parameters under the specified test conditions.

• Average luminous intensity (I_V):At a forward current (I_F) of 1 mA, it is 200-650 µcd. This wide range indicates the devices are binned by luminous intensity.
• Peak Emission Wavelength (λ_p):At I_F=20mA, it is 639 nm (typical value), placing it in the ultra-red region.
• Spectral Line Half-Width (Δλ):20 nm (typical value), defines spectral purity.
• Dominant wavelength (λ_d):631 nm (typical value), with a tolerance of ±1 nm.
• Forward voltage per segment (V_F):At I_F=20mA, is 2.0V to 2.6V, with a tolerance of ±0.1V. This is a key parameter for driver design.
• Reverse current (I_R):At a reverse voltage (V_R) of 5V, maximum 100 µA. Note: This is a test condition; continuous reverse bias operation is prohibited.
• Luminous intensity matching ratio (I_V-m):At I_F=10mA, maximum 2:1. This specifies the maximum allowable brightness variation between segments.
• Crosstalk:≤ 2.5%, meaning minimal unintended illumination between adjacent segments.

3. Bincike System Explanation

The datasheet indicates that the product is "binned by luminous intensity." This implies a binning process where displays are categorized based on their light output measured at a standard test current (likely 1mA or 10mA). Designers can select devices from the same luminous intensity bin (e.g., 400-500 µcd) to ensure brightness uniformity among multiple displays within an assembly, avoiding the "uneven tone issue" mentioned in the precautions. While this document does not explicitly detail binning for wavelength/color or forward voltage, such classifications are common in LED manufacturing to guarantee performance consistency.

4. Performance Curve Analysis

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

• I-V (Current-Voltage) Curve:It shows an exponential relationship, highlighting a typical forward voltage (V_F) of approximately 2.0-2.6V.
• I-V curve (I_Vvs. I_F):shows how light output increases with current until reaching the maximum rated limit. It helps designers select the operating point for desired brightness and efficiency.
• Luminous intensity vs. ambient temperature curve:The optical output decreases with increasing temperature, emphasizing the necessity of thermal management in high-temperature environments.
• Spectral Distribution Diagram:A plot of relative intensity versus wavelength, centered at 639 nm (peak) and 631 nm (dominant wavelength), with a specified 20 nm full width at half maximum.

5. Mechanical and Packaging Information

4. Performance Curve Analysis The datasheet references "typical electrical/optical characteristic curves." Although specific graphs are not provided in the text, standard curves for such devices typically include: I-V (Current-Voltage) Curve: Shows an exponential relationship, highlighting a typical forward voltage (VF) of around 2.0-2.6V. Luminous Intensity vs. Forward Current Curve (IV vs. IF): Illustrates how light output increases with current until reaching maximum rated limits. It helps designers select an operating point for desired brightness and efficiency. Luminous Intensity vs. Ambient Temperature Curve: Shows light output decreasing with rising temperature, emphasizing the need for thermal management in high-temperature environments. Spectral Distribution Graph: A plot of relative intensity versus wavelength, centered at 639 nm (peak) and 631 nm (dominant wavelength), with a specified 20 nm half-width.

This display features a standard Dual In-line Package (DIP) outline. Key dimensional descriptions include:

• All dimensions are in millimeters (mm).
• Unless otherwise specified, the general tolerance is ±0.25 mm.
• The lead tip offset tolerance is ±0.4 mm.
• Defect quality control limits: Foreign matter on segment ≤10 mil, ink contamination ≤20 mil, bubbles within segment ≤10 mil.
• Reflector bow limit is ≤1% of its length.

5.2 Pin Connection and Polarity

This device is acommon anodetype. This means the LED anodes for each digit are internally connected together. The pin definitions are as follows:

• Pin 1, 2, 6, 8: Common anodes for Digit 1, Digit 2, Digit 3, and Digit 4, respectively.
• Pin 4: Common anode for the left colon segments (L1, L2, L3).
• The cathodes (negative terminals) of each segment (A, B, C, D, E, F, G, DP, L1, L2, L3) are distributed across pins 3, 5, 7, 11, 13, 14, 15, and 16.
• Pins 9, 10, and 12 are marked as "No Connection" or "No Pin".

Internal Circuit Diagram:The schematic shows a multiplexed arrangement. The anode of each digit is independent, while the cathodes for the same segment positions (e.g., all 'A' segments) are connected together. To illuminate a specific segment on a specific digit, its corresponding digit anode pin must be driven high (positive voltage), and the corresponding segment cathode pin must be driven low (ground or sink current). This multiplexing is performed rapidly to create the illusion that all digits are lit simultaneously.

6. Soldering, Assembly, and Storage Guidelines

6.1 Welding

Absolute maximum ratings specify the wave soldering profile: 260°C for 3 seconds, with the solder pot 1/16 inch below the mounting plane. For reflow soldering, a standard lead-free soldering profile should be used, with the peak temperature not exceeding the device's maximum temperature rating. Care must be taken during assembly to avoid applying mechanical stress to the display body.

6.2 Storage Conditions

Proper storage is crucial to prevent pin oxidation and performance degradation.

• For LED displays (e.g., LTC-4627JR):Store in the original packaging. Recommended conditions: temperature 5°C to 30°C, humidity below 60% RH. If storage conditions exceed this range, or if the desiccant bag has been opened for more than 6 months, it is recommended to bake the device at 60°C for 48 hours and use it within one week.
• General principles:Avoid long-term storage of large quantities of inventory. Consume stock promptly to ensure freshness and prevent oxidation of the tin-plated leads.

7. Application Notes and Design Considerations

7.1 Key Application Considerations

• Intended Use:Suitable for general electronic equipment (office, communication, household). Not recommended for safety-critical applications (aviation, medical, traffic control) without prior consultation and approval, as failure may endanger life or health.
• Drive Design:
  • Constant Current Drive:It is strongly recommended to use constant current drive instead of constant voltage drive to ensure uniform brightness and protect LEDs from thermal runaway.
  • Voltage Range:The drive circuit must adapt to the full V_FRange (2.0V-2.6V), to provide the intended current to all devices.
  • Reverse and Transient Protection:The circuit must be protected against reverse voltage and voltage spikes during power-up/shutdown to avoid damage due to metal migration and increased leakage current.
  • Current Derating:Select operating current after considering the maximum ambient temperature, using a derating factor of 0.33 mA/°C above 25°C.
• Environment:Avoid rapid temperature changes in humid environments to prevent condensation on the display.
• Mechanical:If using a front panel film/graphic overlay, avoid having it press directly on the display surface as it may shift. If the application involves drop/vibration testing, share the test conditions in advance for evaluation.
• Multi-Display Unit Matching:When assembling two or more displays in a unit, use devices from the same luminous intensity bin to ensure uniform appearance.

7.2 Typical Application Scenarios

The LTC-4627JR is ideally suited for applications requiring clear, medium-sized digital readouts, such as:

• Testing and measurement equipment (multimeters, power supplies).
• Industrial control panels and timers.
• Consumer appliances (microwave ovens, ovens, audio equipment).
• Point of sale terminals and basic information displays.
• Hobbyist and prototyping projects.

8. Technical Comparison and Differentiation

Compared to older technologies such as standard GaAsP or GaP red LEDs, the AlInGaP ultra-red LED chip in the LTC-4627JR offers significantly higher brightness and efficiency. Compared to some modern white or side-lit displays, it provides superior color saturation and viewing angle for pure red indication. Its 0.4-inch digit size fills the gap between smaller, harder-to-read displays and larger, more power-hungry ones. The common-anode multiplexing design is a cost-effective and pin-efficient standard solution for multi-digit displays, although it requires a more complex driver IC than static drive types.

9. Frequently Asked Questions (Based on Technical Parameters)

Q1: What driver IC should I use for the LTC-4627JR?
A: You need a multiplexing driver capable of sourcing current to the common anode pins and sinking current from the segment cathode pins. Common choices are dedicated LED driver ICs like the MAX7219 or TM16xx series, or a microcontroller with sufficient GPIO pins and current capability, using external transistors if needed.

Q2: How to calculate the current-limiting resistor?
A: Use Ohm's Law: R = (V_{Power supply}- V_F) / I_F. Use the maximum V from the datasheet in the calculation._F(2.6V), to ensure that even with device variations, the current never exceeds your chosen I._F. For a 5V power supply and a desired I._Fof 10 mA: R = (5V - 2.6V) / 0.01A = 240 Ω. In a multiplexing circuit, always place the resistor on the cathode (sink) side.

Q3: Can I use it outdoors?
A: The operating temperature range (-35°C to +85°C) allows for use in many outdoor environments. However, considerations must include readability in sunlight (high contrast aids this), potential condensation (avoid rapid temperature changes), and sealing the display behind a protective window to prevent moisture and dust ingress, as the device itself is not waterproof.

Q4: Why is constant current drive recommended?
A: The forward voltage (V_F) of an LED varies with temperature and from device to device. A constant voltage source with a series resistor provides an approximate constant current, but it can vary. A true constant current source ensures the LED always receives the precisely designed current, achieving consistent brightness and longer lifespan, which is especially critical across the -35°C to +85°C temperature range.

10. Design Case Studies

Scenario: Design a simple 4-digit counter/timer.
设计人员选择LTC-4627JR是因为其可读性和标准接口。他们使用一个内置定时器和足够I/O的微控制器。四个GPIO引脚配置为输出，通过小型NPN晶体管（例如，2N3904）驱动数字阳极（引脚1、2、6、8）以提供所需电流。另外七个GPIO引脚（加上一个小数点引脚）配置为开漏输出，并直接连接到段阴极（A-G、DP），每个引脚串联一个220Ω电阻接地，以将段电流设置为约10-12mA（使用5V电源）。固件实现多路复用例程，一次打开一个数字阳极，同时激活该数字的相应段阴极，快速循环所有四个数字（>60Hz）。灰色面板/白色段在产品前面板的深色亚克力窗后提供了极佳的对比度。

11. Working Principles

LTC-4627JR yana aiki bisa ka'idar haske ta lantarki a cikin haɗin P-N na semiconductor. Lokacin da aka yi amfani da ƙarfin lantarki mai kyau wanda ya wuce ƙarfin buɗe diode (≈2.0V), electrons daga Layer N-type AlInGaP suna haɗuwa da ramuka daga Layer P-type. Wannan haɗuwar tana sakin makamashi a cikin nau'in photon (haske). Takamaiman abun da ke cikin gawa na AlInGaP yana ƙayyade ƙarfin tazarar band, wanda kai tsaye yake daidai da tsawon zangon hasken da ake fitarwa (launi) – a cikin wannan misali, jan haske mai tsayi kusan 631-639 nm. Tushen GaAs marar ganuwa yana taimakawa wajen tunzura hasken zuwa sama, yana haɓaka ingancin fitar da haske gabaɗaya. An ƙirƙiri tsarin sassa bakwai ta hanyar sanya guntu LED ɗaya ko jerin guntu a ƙarƙashin kowane yanki na sashi, kuma a haɗa su ta hanyar matrix na haɗaɗɗiya na ciki.

12. Technology Trends

Ko da yake nunin sassa bakwai mai rarrabuwa kamar LTC-4627JR yana da mahimmanci a wasu aikace-aikace saboda sauƙinsa, haske mai ƙarfi, da kuma faɗin kusurwar kallo, babban yanayin ya kasance zuwa ga nunin matrix mai haɗaka (ciki har da LED da OLED) da TFT LCD. Waɗannan nuni suna ba da sassauci mafi girma wajen nuna haruffa, zane-zane, da raye-raye. Duk da haka, ga aikace-aikacen da kawai ke buƙatar lambobi, ƴan haruffa, da kuma babban bayyanawa / amincin gaske, fasahar sassa bakwai har yanzu tana ci gaba da haɓakawa. Trends sun haɗa da kayan aiki mafi inganci, ƙananan ƙarfin lantarki na aiki, kayan aikin da aka ɗora a saman (SMD) don haɗawa ta atomatik, da kuma nuni masu haɗakar direbobi da hanyoyin sadarwa (kamar I2C ko SPI) don ƙara sauƙaƙa ƙirar tsarin da rage adadin fil ɗin microcontroller.