LTD-323JR LED Digital Tube Datasheet - 0.3 Inch Character Height - 2.6V Forward Voltage - Super Red Color - Simplified Chinese Technical Documentation

1. Product Overview

LTD-323JR na'urar nuni ce ta lambobi bakwai mai inganci, wacce aka tsara don aikace-aikacen da ke buƙatar karatun lambobi masu haske, masu haske, kuma masu dogaro. Babban aikinta shine nuna lambobi (0-9) da wasu haruffan lambobi ta hanyar sassan LED masu zaman kansu.

An tsara wannan na'urar ne da fifikon karantawa da inganci. Abubuwan haskakawa suna amfani da fasahar AlGaInP (aluminum gallium indium phosphide) semiconductor. Wannan tsarin kayan yana da suna wajen samar da haske mai inganci na ja da amber. Allon nuni yana amfani da panel baki, yana ba da bambanci mai kyau ta hanyar ɗaukar hasken muhalli, yayin da fararen sassan ke watsa hasken ja daidai, don samar da haruffa masu haske da kaifi.

Babban fa'idar wannan na'urar nuni shine tsarinta mai ƙarfi, wanda ke da ingantaccen dogaro da tsawon rayuwa fiye da sauran fasahohin nuni kamar vacuum fluorescent ko incandescent. Ana rarrabe shi bisa ƙarfin haske, yana tabbatar da daidaiton haske tsakanin rukunin samarwa, don haka yana ba da kamanni iri ɗaya a aikace-aikacen lambobi da yawa.

1.1 Main Features and Target Applications

LTD-323JR yana da sifofi masu mahimmanci da yawa, waɗanda suka sa ya dace da aikace-aikacen masana'antu, kasuwanci da na mabukaci.

• 0.3-inch digit height (7.62 mm):Wannan ƙaramin girma yana da kyakkyawan daidaito tsakanin bayyani da ƙirar sararin samaniya, yana da kyau sosai don allunan kayan aiki, na'urorin gwaji, tashoshin tallace-tallace da nunin kayan gida.
• Sassa masu daidaito ci gaba:Ƙirar sashe ba ta da gibi ko katsewa, tana samar da lambobi masu santsi da ƙwararru, wanda ke ƙara karantawa.
• Ƙarancin buƙatun wutar lantarki:Yana aiki a ƙaramin ƙarfin halin yanzu, yana da inganci a cikin makamashi, yana dacewa da na'urorin da aka yi amfani da baturi ko ƙarancin wutar lantarki.
• Haske mai girma da bambanci mai girma:The combination of bright AlGaInP LEDs and a black panel ensures that the display is easy to read even under strong ambient light conditions.
• Wide Viewing Angle:The optical design allows for clear reading of the display content from a wide angle, increasing the flexibility of device placement and user interaction.
• Solid-State Reliability:With no moving parts or fragile filaments, LED displays offer excellent resistance to shock and vibration, as well as a very long service life.

Typical applications include digital multimeters, clock radios, industrial control panels, medical equipment, automotive dashboards (for auxiliary displays), and household appliances such as microwave ovens or washing machines.

2. Detailed Technical Specifications

This section provides a detailed and objective analysis of the electrical and optical parameters specified in the datasheet. Understanding these parameters is crucial for proper circuit design and ensuring optimal display performance.

2.1 Absolute Maximum Ratings

These ratings define the stress limits beyond which permanent damage to the device may occur. Operation outside these limits is not recommended.

• Power Dissipation per Segment:70 mW. This is the maximum power that a single LED segment can safely dissipate as heat under continuous operation. Exceeding this value may lead to overheating and accelerated performance degradation.
• Peak Forward Current per Segment:90 mA (duty cycle 1/10, pulse width 0.1ms). This rating applies to pulsed operation, allowing higher instantaneous current for higher peak brightness in multiplexed displays. The average current must still comply with the continuous rating.
• Forward current per segment:25 mA at 25°C. This is the maximum recommended DC current for continuous segment illumination. The datasheet specifies a derating factor of 0.33 mA/°C above 25°C, meaning the maximum allowable current decreases as ambient temperature rises to prevent thermal runaway.
• Reverse voltage per segment:5 V. Applying a reverse voltage higher than this may cause LED junction breakdown and failure.
• Operating and storage temperature range:-35°C to +85°C. The device is rated for operation and storage within this industrial temperature range.
• Soldering temperature:Maximum 260°C for 3 seconds, measured 1.6mm below the mounting plane. This defines the reflow soldering temperature profile to avoid damage to the plastic package or internal bond wires.

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

These are typical operating parameters under specified test conditions.

• Average luminous intensity (I_V):200 (min.), 600 (typ.) µcd, at I_F=1mA. This is a measure of perceived brightness. The wide range indicates a grading system exists; designers must account for this variation, or select graded parts for uniform appearance.
• Peak emission wavelength (λ_p):639 nm (typ.), at I_F=20mA. This is the wavelength at which the optical power output is maximum, located in the red region of the visible spectrum.
• Spectral line half-width (Δλ):20 nm (typical value). This indicates the spectral purity or bandwidth of the emitted light. 20 nm is a typical value for a standard red LED, producing a saturated red color.
• Dominant Wavelength (λ_d):631 nm (typical value). This is the single wavelength that the human eye perceives as most closely matching the LED's color, slightly shorter than the peak wavelength.
• Forward Voltage per Segment (V_F):2.0 (min), 2.6 (typical) V, at I_F=20mA. This is the voltage drop across the LED when the specified current flows through it. It is crucial for designing the current-limiting resistor value: R = (V_{Power Supply}- V_F) / I_F.
• Reverse Current per Segment (I_R):100 µA (maximum), at V_R=5V condition. This is the small leakage current that flows when the LED is reverse-biased within its maximum ratings.
• Luminous intensity matching ratio (I_V-m):2:1 (maximum). This parameter specifies the maximum allowable brightness difference between different segments of the same digit or between different digits, ensuring visual uniformity.

3. Grading System Description

The datasheet indicates that the device is "graded by luminous intensity." This refers to the grading or screening process performed during manufacturing.

Luminous intensity grading:Due to inherent variations in semiconductor epitaxial growth and chip manufacturing processes, LEDs from the same production batch may have different brightness outputs. Manufacturers test and classify (bin) these LEDs based on their measured luminous intensity at a standard test current (e.g., 1mA as specified in the datasheet). The typical intensity range of 200-600 µcd for the LTD-323JR indicates that multiple bins likely exist. For applications requiring consistent brightness across multiple displays (such as multi-digit panels), specifying parts from the same intensity bin is crucial. The 2:1 intensity matching ratio is a parameter guaranteed internally by the device.

Although the datasheet does not explicitly mention voltage or wavelength binning for this part, it is common practice. If critical for the application, designers should consult the manufacturer for detailed binning information.

4. Performance Curve Analysis

The datasheet references "Typical Electrical/Optical Characteristic Curves." While specific graphs are not provided in the text, we can discuss the standard relationships they typically describe, which are crucial for understanding device behavior.

• Forward Current vs. Forward Voltage (I-V Curve):This curve shows the exponential relationship between the diode's current and voltage. For the LTD-323JR, the typical V_Fis 2.6V at 20mA. This curve helps designers understand the voltage threshold and how V_Fvaries slightly with temperature and current.
• Luminous Intensity vs. Forward Current (I-L Curve):The graph shows that within the normal operating range, the light output is roughly proportional to the forward current. It is not perfectly linear, especially at very high currents, where efficiency decreases due to heating.
• Luminous Intensity vs. Ambient Temperature:The light output of an LED typically decreases as the junction temperature increases. This curve is crucial for applications operating over a wide temperature range to ensure sufficient brightness is maintained at high temperatures.
• Spectral Distribution:A graph showing the relative optical power at each wavelength. It confirms the peak wavelength (639 nm) and dominant wavelength (631 nm), and shows the shape of the emission spectrum, characterized by a half-width of 20 nm.

5. Mechanical and Packaging Information

5.1 Package Dimensions and Pin Definitions

The device uses a standard Dual In-line Package (DIP), suitable for through-hole PCB mounting. Exact dimensions are provided in the drawing (referenced but not detailed in the text), with a tolerance of ±0.25 mm.

Pin Connections:

1. Pin 1: Cathode G (Segment G, typically the center segment)
2. Pin 2: No Connection
3. Pin 3: Cathode A (Segment A, top segment)
4. Pin 4: Cathode F (Segment F, upper left segment)
5. Pin 5: Common Anode (Digit 2)
6. Pin 6: Cathode D (Segment D, middle bottom segment)
7. Pin 7: Cathode E (Segment E, bottom left segment)
8. Pin 8: Cathode C (Segment C, top right segment)
9. Pin 9: Cathode B (Segment B, top right segment)
10. Pin 10: Common Anode (Digit 1)

Internal Circuit Diagram:This display uses a "duplex common anode" configuration. This means it contains two independent digits (Digit 1 and Digit 2). Each digit has its own common anode pin (Pin 10 and Pin 5). All corresponding segment cathodes (A, B, C, D, E, F, G) for both digits are internally connected and brought out to common cathode pins (Pin 3, 9, 8, 6, 7, 4, 1). This architecture allows multiplexing: by enabling one anode (digit) at a time and driving the corresponding cathode pins for that digit, multiple digits can be controlled with fewer I/O pins.

6. Soldering and Assembly Guide

Adhering to the specified soldering temperature profile is crucial to prevent damage.

• Reflow Soldering:The recommended peak temperature is 260°C, measured 1.6mm below the package body, for a maximum duration of 3 seconds. This profile is typical for lead-free soldering processes. The plastic package material has a specific glass transition temperature; exceeding thermal limits may cause package cracking, deformation, or internal bond wire failure.
• Hand Soldering:If manual soldering is necessary, use a temperature-controlled soldering iron. Apply heat to the pin and PCB pad, avoiding direct contact with the plastic body. Limit soldering time per pin to 3-5 seconds to minimize heat transfer to the package.
• Cleaning:Use only cleaning agents compatible with the display's plastic material. Avoid ultrasonic cleaning unless explicitly approved, as it may induce mechanical stress.
• Storage Conditions:Store in a dry, anti-static environment within the specified temperature range (-35°C to +85°C) to prevent moisture absorption (which can cause "popcorn" effect during reflow) and electrostatic discharge damage.

7. Application Design Considerations

7.1 Drive Circuit Design

Don ha LTD-323JR nufa'adu da aminci, tsarin iyakancewar kwarara ya zama dole. Hanyar da aka fi sani ita ce haɗa resistor a jere tare da kowane sashi.

Misalin lissafi:Ga wutar lantarki na 5V (V_CC), tare da madaidaicin kwararar gaba na 20mA da madaidaicin V na 2.6V_Fdon nufa'adar sashi ɗaya:
R_{Iyakancewar kwarara}= (V_CC- V_F) / I_F= (5V - 2.6V) / 0.020A = 120 Ω.
A standard 120Ω resistor will be used. The power dissipation in the resistor is I²R = (0.02)²* 120 = 0.048W, so a standard 1/8W or 1/4W resistor is sufficient.

Notes:

• Use themaximum value V_F(2.6V) from the datasheet for calculation to ensure that even if V_F part.
• For lower-rated devices, the current will also not exceed the limit. For multiplexing operation, the instantaneous current during the brief on-time can be higher to achieve the desired average brightness. For example, at a 1/4 duty cycle, the peak current might be 80mA to achieve a 20mA average, but it must not exceed the 90mA peak rating. Use transistors (BJTs or MOSFETs) or dedicated driver ICs (such as 74HC595 shift registers with constant-current outputs or MAX7219 display drivers) to sink the segment and digit currents, especially when multiplexing multiple digits.
• Use transistors (BJTs or MOSFETs) or dedicated driver ICs (like 74HC595 shift registers with constant-current outputs or MAX7219 display drivers) to sink/sink the segment and digit currents, especially for multiplexing more than a few digits.

7.2 Thermal Management

Although the power dissipation of a single segment is small (maximum 70mW), a multi-digit display driven at high currents generates significant heat. Ensure adequate airflow around the display and consider the following:

• Adhere to the current derating curve for ambient temperatures exceeding 25°C.
• Avoid placing the display near other heat-generating components.
• For high brightness requirements, consider using pulse operation (PWM) with higher peak current but lower duty cycle, rather than high continuous current, as this can improve efficiency and reduce average heat generation.

8. Technical Comparison and Differentiation

The LTD-323JR, based on AlGaInP technology, offers significant advantages compared to older LED technologies such as GaAsP (Gallium Arsenide Phosphide) and GaP (Gallium Phosphide):

• Comparison with GaAsP/GaP Red LEDs:AlGaInP LEDs are significantly brighter and more efficient. They produce a more saturated "true" red light (around 630-640 nm) compared to the orange-red hue of older technologies. This achieves the claim of "High Brightness and High Contrast."
• Comparison with Larger Size Displays:0.3-inch size provides a good compromise. Smaller displays save space but may be harder to read from a distance; larger displays are more visible but consume more board area and power.
• Compared to common cathode displays:When interfacing with microcontroller GPIO pins configured as current sinks (pulled low to ground), a common anode configuration is often preferred, which is a common and robust driving method.

9. Frequently Asked Questions (FAQ)

Q1: What is the purpose of the "No Connect" pin (Pin 2)?
A1: This pin exists mechanically to maintain the standard 10-pin DIP package spacing and physical stability, but has no internal electrical connection. It should be left unconnected or only connected to a PCB pad for mechanical support.

Q2: Can I drive this display directly from a microcontroller pin?
A2: It is not recommended to drive LED segments directly from standard GPIO pins. Most MCU pins have limited current sourcing/sinking capability (typically an absolute maximum of 20-25mA per pin, with a lower total for the entire port). Exceeding this may damage the MCU. Always use current-limiting resistors and consider using transistors or driver ICs to handle the current.

Q3: Yadda ake samun daidaitaccen haske a aikace-aikacen lambobi da yawa?
A3: Da farko, tabbatar duk sassan suna amfani da irin wutar lantarki guda. Na biyu, ka saka wa masana'anta cewa na'urorin nunawa sun fito daga matakin haske iri ɗaya. Na uku, idan har yanzu akwai ɗan bambanci, aiwatar da daidaita haske ta software ko amfani da IC mai sarrafa ƙarfin sassa masu zaman kansu.

Q4: Me "Dual Common Anode" ke nufi ga multiplexing?
A4: Wannan yana nufin kana da fil ɗin gama gari masu zaman kansu guda biyu (ɗaya kowace lamba). Don yin multiplexing, kana buƙatar kunna anode na lamba ta 1 (saita fil 10 zuwa high idan ana amfani da transistor na PNP; ko kuma haɗa shi da ƙasa idan anode ana sarrafa shi zuwa low), saita tsarin cathode na lambar da ake buƙata don lamba ta 1, jira ɗan gajeren lokaci, sannan kashe lamba ta 1, kunna anode na lamba ta 2, saita tsarin cathode don lamba ta 2, kuma maimaita haka cikin sauri. Idon mutum zai ga duka lambobin biyu suna haskakawa a kai a kai.

10. Design Case Study

Yanayi:Zana mai ƙidaya lambobi biyu mai sauƙi don na'urar dakin gwaje-gwaje, wanda ke samun wutar lantarki daga 5V, kuma microcontroller na 3.3V ke sarrafa shi.

Aiwarta:

1. Current Limiting:Connect a 120Ω resistor in series on each of the 7 segment cathode lines.
2. Segment Drive:Connect the cathode lines (via their resistors) to the drain pins of 7 N-channel MOSFETs (e.g., 2N7002). Connect the source pins to ground. Connect the MOSFET gates to 7 GPIO pins of the MCU via 10kΩ pull-down resistors.
3. Digit Drive (Anode Switching):Connect the two common anode pins (pins 5 and 10) to the collectors of two PNP transistors (e.g., 2N3906). Connect the emitters to the 5V supply. Connect the bases to two additional GPIO pins of the MCU via 10kΩ resistors. Place a 100Ω resistor between each base and the MCU pin for current limiting.
4. Logic:MCU runs the multiplexing routine. To display '1' on digit 1 and '5' on digit 2:
   • Set the GPIOs for segments B and C (for '1') to logic high to turn on their MOSFETs, grounding these cathodes.
   • Set the GPIO for digit 1's PNP transistor to low (turn it on, connecting 5V to the anode).
   • Wait for 5-10ms.
   • Set the GPIO for digit 1 to high (turn it off).
   • Set the GPIOs for segments A, F, G, C, D (for '5') to high.
   • Set the GPIO for digit 2's PNP transistor to low.
   • Wait 5-10ms, then repeat.

11. Technical Principles

LTD-323JR is based on solid-state light emission from a semiconductor p-n junction. The active material is AlGaInP (aluminum gallium indium phosphide). When a forward voltage exceeding the junction's built-in potential (approximately 2.0-2.6V) is applied, electrons from the n-type region and holes from the p-type region are injected into the active region. There, they recombine, releasing energy in the form of photons (light). The specific composition of the AlGaInP alloy determines the semiconductor's bandgap energy, which directly dictates the wavelength (color) of the emitted light. The use of an opaque GaAs substrate helps reflect light upward, improving extraction efficiency. The black panel plastic package contains diffusing material on the segments to create a uniform appearance and includes filters to enhance contrast.

12. Industry Trends

While discrete seven-segment LED displays like the LTD-323JR remain essential in many applications due to their simplicity, robustness, and low cost, there are several notable trends in display technology:

• Integrated:The trend is moving towards displays with integrated driver ICs ("smart displays"), which simplify the main controller interface, typically using serial protocols like I2C or SPI.
• Alternative Technologies:For applications requiring more complex graphics or alphanumerics, dot-matrix LED displays, OLEDs (Organic LEDs), and LCDs are increasingly used. However, for simple numeric readouts requiring high brightness and wide viewing angles, seven-segment LEDs like the LTD-323JR are often the preferred choice.
• Miniaturization and Efficiency:Continuous advancements in LED chip technology are constantly improving luminous efficacy (lumens per watt), enabling brighter displays at lower currents or allowing for further miniaturization.
• Color Options:While this datasheet specifies an ultra-red color, the same package and driving concepts apply to displays using other LED technologies for different colors, such as InGaN for blue and green, or phosphor-converted white LEDs.

LTD-323JR yana wakiltar mafita mai cikakkiya, amintacce kuma mai sauƙin fahimta, wanda ke ci gaba da taka muhimmiyar rawa a cikin ƙirar lantarki da ke buƙatar nuni mai bayyananne kuma amintacce na lambobi.