LTS-5601AJG 0.56-inch Seven-Segment LED Display Datasheet - Digit Height 14.22mm - Green AlInGaP - English Technical Documentation

1. Product Overview

The LTS-5601AJG is a high-performance, single-digit, seven-segment alphanumeric display module. Its primary function is to provide clear, bright numeric and limited alphabetic character representation in electronic devices. The core technology is based on Aluminium Indium Gallium Phosphide (AlInGaP) semiconductor material, which is specifically engineered for high-efficiency light emission in the green-yellow spectrum. This device is categorized as a common anode configuration, meaning the anodes of all LED segments are connected internally to common pins, simplifying current drive circuitry. The display features a gray faceplate which enhances contrast and improves readability under various ambient lighting conditions by reducing reflections. The segments themselves emit a distinct green color, chosen for its high luminous efficacy and excellent visibility to the human eye. This product is designed for applications requiring reliable, long-lasting, and energy-efficient numerical indication.

1.1 Core Advantages and Target Market

The display offers several key advantages that make it suitable for a wide range of industrial and consumer applications. Its low power requirement is a significant benefit, allowing for integration into battery-powered or energy-conscious systems. The high brightness and contrast ratio ensure legibility even in brightly lit environments. A wide viewing angle provides consistent visual performance from various perspectives, which is crucial for panel meters and instrumentation. The solid-state reliability of LED technology, with no moving parts and high resistance to shock and vibration, ensures a long operational lifespan. The device is also categorized for luminous intensity, meaning units are binned and tested to meet specific brightness criteria, guaranteeing performance consistency in production runs. The target markets for this component include test and measurement equipment, industrial control panels, medical devices, automotive dashboards (for aftermarket or auxiliary displays), consumer appliances, and any electronic system requiring a durable and clear numeric readout.

2. Technical Parameter Deep-Dive

This section provides a detailed, objective analysis of the key electrical, optical, and thermal parameters specified in the datasheet. Understanding these values is critical for proper circuit design and ensuring the display operates within its safe and optimal performance window.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. They are not intended for normal operation.

• Power Dissipation per Segment: 70 mW. This is the maximum amount of electrical power that can be converted into heat (and light) by a single segment without risk of damage. Exceeding this value, especially continuously, can lead to overheating, accelerated lumen depreciation, and eventual failure.
• Peak Forward Current per Segment: 60 mA (at 1/10 duty cycle, 0.1ms pulse width). This rating allows for brief pulses of higher current to achieve momentary peaks in brightness, useful for multiplexing schemes or highlighting. The specified duty cycle and pulse width are critical; the average current must still comply with the continuous rating.
• Continuous Forward Current per Segment: 25 mA (at 25°C). This is the recommended maximum current for steady-state, continuous illumination of a segment. The datasheet specifies a derating factor of 0.33 mA/°C above 25°C. This means if the ambient temperature (Ta) rises, the maximum allowable continuous current must be reduced linearly to prevent overheating. For example, at 50°C, the max current would be 25 mA - (0.33 mA/°C * 25°C) = 16.75 mA.
• Reverse Voltage per Segment: 5 V. LEDs have a low reverse breakdown voltage. Applying a reverse bias greater than 5V can cause a sudden increase in reverse current, potentially damaging the PN junction.
• Operating & Storage Temperature Range: -35°C to +85°C. The device is rated to function and be stored within this broad temperature range, making it suitable for harsh environments.
• Solder Temperature: 260°C for 3 seconds, measured 1/16 inch (≈1.6mm) below the seating plane. This defines the reflow soldering profile to avoid thermal damage to the LED chips during assembly.

2.2 Electrical & Optical Characteristics

These parameters are measured under specific test conditions (typically Ta=25°C) and define the typical performance of the device.

• Average Luminous Intensity (I_V): 320 μcd (Min), 900 μcd (Typ) at I_F=1mA. This is the measure of perceived light power emitted by a segment. The wide range (Min to Typ) indicates natural variation in manufacturing; designers should use the minimum value for worst-case brightness calculations. The test current of 1mA is a standard low-current condition for characterizing brightness efficiency.
• Peak Emission Wavelength (λ_p): 571 nm (Typ) at I_F=20mA. This is the wavelength at which the spectral power distribution of the emitted light is maximum. 571 nm is in the green-yellow region of the visible spectrum.
• Spectral Line Half-Width (Δλ): 15 nm (Typ). This indicates the spectral purity or bandwidth of the emitted light. A value of 15 nm is relatively narrow, characteristic of AlInGaP LEDs, resulting in a saturated green color.
• Dominant Wavelength (λ_d): 572 nm (Typ). This is the single wavelength perceived by the human eye that best matches the color of the light. It is very close to the peak wavelength in this case.
• Forward Voltage per Segment (V_F): 2.05V (Min), 2.6V (Typ) at I_F=20mA. This is the voltage drop across the LED segment when operating. It is crucial for designing the current-limiting circuitry. The driver supply voltage must be higher than V_F. The typical 2.6V is higher than standard GaAsP red LEDs but lower than many blue/white LEDs.
• Reverse Current per Segment (I_R): 100 μA (Max) at V_R=5V. This is the leakage current when the maximum reverse voltage is applied.
• Luminous Intensity Matching Ratio (I_V-m): 2:1 (Max). This specifies the maximum allowable ratio between the brightest and dimmest segment within a single device when driven under identical conditions (I_F=1mA). A ratio of 2:1 ensures reasonable uniformity in appearance.

3. Binning System Explanation

The datasheet indicates the product is "categorized for luminous intensity." This refers to a post-production sorting process known as "binning." After manufacture, individual displays are tested and sorted into different performance groups (bins) based on key parameters. For the LTS-5601AJG, the primary binned characteristic is its luminous intensity at a standard test current (likely 1mA or 20mA). This ensures that customers receive units with consistent brightness levels. While the datasheet provides the full Min/Typ range, production lots are typically offered within tighter intensity bands. Designers should consult specific procurement documentation or the manufacturer for available bin codes. Consistent binning is essential for applications where multiple displays are used side-by-side, preventing noticeable brightness differences between units.

4. Performance Curve Analysis

The datasheet references "Typical Electrical / Optical Characteristic Curves." While the specific graphs are not provided in the text, we can infer their standard content and importance. These curves visually represent the relationship between key parameters, providing deeper insight than single-point data.

4.1 Forward Current vs. Forward Voltage (I-V Curve)

This fundamental curve shows the exponential relationship between the current flowing through the LED and the voltage across it. It graphically illustrates the forward voltage (V_F) specification. The curve will show a "knee" voltage (around 2V) after which current increases rapidly with a small increase in voltage. This highlights why LEDs must be driven by a current-limited source, not a voltage source, to prevent thermal runaway.

4.2 Luminous Intensity vs. Forward Current

This curve shows how light output increases with drive current. For AlInGaP LEDs, the relationship is generally linear over a wide range of currents, but it will eventually sub-linearize at very high currents due to efficiency droop (increased heat generation). This curve helps designers choose an operating current to achieve desired brightness while balancing efficiency and lifetime.

4.3 Luminous Intensity vs. Ambient Temperature

This curve depicts the thermal dependence of light output. As the junction temperature of the LED increases, its luminous intensity typically decreases. The slope of this curve quantifies the thermal derating of brightness. This is critical for designs operating in elevated temperature environments, as the display may appear dimmer than expected at room temperature.

4.4 Relative Intensity vs. Wavelength (Spectrum)

This graph plots the spectral power distribution, showing the intensity of light emitted at each wavelength. It would center around the 571-572 nm peak/dominant wavelength with a shape defined by the 15 nm half-width. This curve confirms the color characteristics of the LED.

5. Mechanical & Packaging Information

The device is presented with a detailed package dimension drawing (referenced but not detailed in the text). Key mechanical features include a 0.56-inch (14.22 mm) digit height, which is a standard size for medium-large numeric displays. The package is a through-hole type (DIP - Dual In-line Package) with 10 pins on a 0.1-inch (2.54 mm) pitch, a common standard for easy PCB mounting and manual prototyping. The gray face and green segments are part of the package design. The "Rt. Hand Decimal" note in the description indicates the position of the decimal point relative to the digit. A right-hand decimal is standard for most numeric displays. The internal circuit diagram shows the common anode connection: pins 3 and 8 are internally tied together as the common anode for all segments, while pins 1, 2, 4, 5, 6, 7, 9, and 10 are the individual cathodes for segments E, D, C, DP, B, A, F, and G respectively. This configuration is optimal for multiplexing with a microcontroller, where the common anodes are driven sequentially (sourced) and the cathodes are sunk to ground via current-limiting resistors to illuminate specific segments.

6. Soldering & Assembly Guidelines

Proper handling is essential to maintain reliability. The absolute maximum rating specifies a soldering temperature of 260°C for 3 seconds, measured 1.6mm below the seating plane. This aligns with standard lead-free reflow soldering profiles (e.g., IPC/JEDEC J-STD-020). During wave soldering or hand soldering, care must be taken to minimize the total heat exposure time to prevent damage to the LED chip, wire bonds, or the plastic package. The use of a heatsink on the leads during manual soldering is recommended. Avoid applying mechanical stress to the package or leads. Storage should be in a dry, anti-static environment within the specified -35°C to +85°C temperature range to prevent moisture absorption (which can cause "popcorning" during reflow) and material degradation.

7. Application Suggestions

7.1 Typical Application Circuits

The most common drive method for a common anode display like the LTS-5601AJG is multiplexing. In a multiplexed circuit, the common anode pins (3 & 8) are connected to the collector (or drain) of an NPN transistor (or N-channel MOSFET) which acts as a high-side switch. The emitter/source is connected to the positive supply (Vcc). The base/gate is controlled by a microcontroller GPIO pin. Each segment cathode pin is connected to a current-limiting resistor, which then connects to a second transistor or a dedicated LED driver IC (configured as a current sink) controlled by the microcontroller. The microcontroller rapidly cycles through turning on one digit's anode transistor at a time while setting the appropriate cathode patterns for that digit. The persistence of vision makes all digits appear continuously lit. A typical forward current of 10-20 mA per segment is used, with resistors calculated as R = (Vcc - V_F - V_CE(sat)) / I_F. For a 5V supply, V_F=2.6V, and V_CE(sat)=0.2V, targeting I_F=15mA gives R = (5 - 2.6 - 0.2) / 0.015 ≈ 147 Ω (use 150 Ω).

7.2 Design Considerations

• Current Limiting: Always use series resistors or constant-current drivers. Never connect an LED directly to a voltage source.
• Multiplexing Frequency: Use a refresh rate high enough to avoid visible flicker, typically >60 Hz per digit. For a 4-digit multiplex, the scan rate should be >240 Hz.
• Peak Current in Multiplexing: Since each digit is only on for a fraction of the time (duty cycle = 1/N for N digits), the instantaneous current per segment can be set higher than the continuous DC rating to achieve a desired average brightness, but it must not exceed the peak forward current rating. For example, in a 4-digit multiplex (1/4 duty), to achieve an average brightness equivalent to 10mA DC, you could drive with 40mA pulses, which is within the 60mA peak rating.
• Viewing Angle: Position the display considering its wide viewing angle to ensure readability for the end-user.
• ESD Protection: Although not explicitly stated as sensitive, standard ESD precautions during handling and assembly are advisable for all semiconductor devices.

8. Technical Comparison & Differentiation

The LTS-5601AJG differentiates itself primarily through its use of AlInGaP technology. Compared to older technologies like standard GaAsP (Gallium Arsenide Phosphide) used for red and yellow LEDs, AlInGaP offers significantly higher luminous efficiency, resulting in brighter displays for the same input current, or equivalent brightness at lower power. It also provides better temperature stability and color saturation. Compared to GaP (Gallium Phosphide) green LEDs, AlInGaP green typically has a more pure green color (shorter wavelength) and higher efficiency. When compared to modern InGaN (Indium Gallium Nitride) blue/green/white LEDs, AlInGaP is generally more efficient in the red-amber-yellow-green spectrum but cannot produce blue or white light. For a pure green numeric display, AlInGaP represents a high-performance, mature technology choice. Its common anode configuration is also a practical advantage for microcontroller-based systems, as it simplifies the sourcing side of the drive circuit.

9. Frequently Asked Questions (Based on Parameters)

9.1 What is the purpose of having two common anode pins (3 and 8)?

The two pins are internally connected. This design serves multiple purposes: 1) It provides symmetry and mechanical stability for the package. 2) It allows for better current distribution, reducing the current density through a single pin, which is beneficial for high-brightness applications. 3) It offers flexibility in PCB layout; the designer can choose to connect one or both pins to the drive circuit.

9.2 Can I drive this display with a 3.3V microcontroller system?

Yes, but careful design is needed. The typical forward voltage (2.6V) is less than 3.3V, so it is possible. However, the voltage headroom (3.3V - 2.6V = 0.7V) is low for a simple series resistor. This small voltage drop means that minor variations in V_F or the supply voltage will cause large changes in current. For stable operation, it is better to use a dedicated constant-current LED driver IC or a transistor-based current source that can operate with low headroom voltage, rather than a simple resistor.

9.3 How do I calculate the total power consumption of the display?

For a static (non-multiplexed) display with all segments and the decimal point lit: Power = Number_of_lit_segments * I_F * V_F. For 8 segments (7+DP) at I_F=20mA and V_F=2.6V, P = 8 * 0.02 * 2.6 = 0.416 W. In a multiplexed application, the average power is the sum of the power in each lit segment averaged over time. For a 4-digit multiplex with one digit active at a time, the average current per segment is I_F / 4.

10. Practical Design Case Study

Scenario: Designing a simple 4-digit voltmeter display using a microcontroller.

Implementation: Four LTS-5601AJG displays are used. The common anodes of each digit are connected to four separate GPIO pins via NPN transistors (e.g., 2N3904). The eight segment cathodes (A-G and DP) from all four displays are connected together and then connected to eight other GPIO pins via 150Ω current-limiting resistors. The microcontroller measures a voltage with its ADC, converts it to a decimal number, and extracts four digits. It then enters a continuous loop: it turns off all anode transistors, sets the cathode pattern for Digit 1's value, turns on Digit 1's anode transistor, waits for a short time (~2ms), then repeats for Digits 2, 3, and 4. This cycle repeats at a rate of over 100 Hz, making the display appear solid. The brightness is controlled by the value of the current-limiting resistor and/or the duty cycle (on-time) within each digit's period.

11. Operating Principle

The LTS-5601AJG is based on the principle of electroluminescence in a semiconductor PN junction. The active region is composed of AlInGaP layers grown on a non-transparent GaAs substrate. When a forward bias voltage exceeding the junction's built-in potential is applied (anode positive relative to cathode), electrons from the N-type material and holes from the P-type material are injected into the active region. There, they recombine, releasing energy in the form of photons. The specific composition of the AlInGaP alloy determines the bandgap energy, which in turn dictates the wavelength (color) of the emitted light—in this case, green (~572 nm). The non-transparent substrate helps reflect emitted light outward, improving overall light extraction efficiency. The gray face filter absorbs ambient light, increasing contrast by reducing reflections off the underlying material.

12. Technology Trends

AlInGaP technology is a mature and highly optimized solution for high-efficiency red, amber, and pure green LEDs. Current trends in display technology for such indicators include a continued push for even higher luminous efficacy (more lumens per watt) to enable lower power consumption and reduced heat generation. There is also ongoing development in packaging to allow for higher maximum drive currents and better thermal management, enabling brighter displays. Furthermore, integration is a key trend; while discrete seven-segment displays remain popular for their simplicity and cost-effectiveness, there is a growing market for integrated display modules that include the driver IC, microcontroller interface (like I2C or SPI), and sometimes even a character generator, simplifying the design process for end engineers. However, for applications requiring customization, high brightness, or specific mechanical form factors, discrete components like the LTS-5601AJG continue to be a vital and reliable choice.