LTP-747KA LED Dot Matrix Display Datasheet - 0.7-inch (17.22mm) Character Height - Red-Orange - AlInGaP Technology - Simplified Chinese Technical Documentation

1. Product Overview

LTP-747KA is a single-character, 5x7 dot matrix alphanumeric display module. Its primary function is to provide clear and bright visual output for characters and symbols in various electronic applications. The core component of this display is a light-emitting diode (LED) chip made from advanced aluminum indium gallium phosphide (AlInGaP) semiconductor material, responsible for producing the iconic red-orange light output. This material technology is renowned for its high efficiency and excellent performance characteristics.

The device is constructed with a gray panel and features white dots or segments, which enhances the contrast and readability between the light-emitting elements and the background. The display is classified according to its luminous intensity, meaning the units are binned or sorted based on their measured light output to ensure consistent brightness within a specified range for applications requiring uniform luminance.

2. Detailed Technical Specifications

Sehemu hii inatoa uchambuzi wa kina na usio na upendeleo wa vigezo muhimu vya kiufundi vilivyobainishwa katika hati ya vipimo.

2.1 Tabia ya Kioo

Optical performance is the core of display functionality. Key parameters are measured under specific test conditions, typically at an ambient temperature (T_A) of 25°C.

• Average Luminous Intensity (I_V):This is a metric that measures the perceived power of light emitted from a single point. When driven at a peak current (I_P) of 32mA with a 1/16 duty cycle, the typical value is 3400 microcandelas (µcd), with a minimum of 1650 µcd. The 1/16 duty cycle is a common multiplexing scheme for dot matrix displays, where each row is active for only 1/16 of the time to manage power and heat.
• Peak Emission Wavelength (λ_p):The wavelength at which the intensity of the LED's emission spectrum reaches its maximum. For the LTP-747KA, this value is typically 621 nanometers (nm), placing it firmly within the red-orange region of the visible spectrum.
• Dominant Wavelength (λ_d):Thamani hii ni 615 nm, ambayo ni urefu wa wimbi mmoja unaoelezea vyema jinsi jicho la binadamu linavyoona rangi. Inatofautisha kidogo na urefu wa wimbi wa kilele kutokana na umbo la wigo wa mionzi ya LED.
• Upana wa nusu ya mstari wa wigo (Δλ):Kigezo hiki kwa kawaida ni 18 nm, kinachoonyesha upana wa wigo wa mionzi katika nusu ya nguvu yake ya juu zaidi. Upana wa nusu unaopungua zaidi unaonyesha wigo safi zaidi na usitawi mkubwa wa rangi.
• Uwiano wa ulinganifu wa nguvu ya mwanga (I_V-m):The maximum is specified as 2:1. This ratio defines the permissible brightness variation between the brightest and darkest points on the display. A lower ratio indicates better uniformity.

2.2 Tabia ya Umeme

Kuelewa tabia ya umeme ni muhimu kwa kubuni sakiti kwa usahihi na kuhakikisha uimara wa muda mrefu.

• Kila nukta ya voltage ya mbele (V_F):Mshuko wa voltage kwenye LED wakati wa mkondo wa mbele. Wakati mkondo wa mbele (I_F) ni 20mA, thamani ya kawaida ni 2.6V, na thamani ya juu ni 2.6V. Thamani ya chini ni 2.05V. Mipaka hii lazima izingatiwe wakati wa kubuni sakiti ya kudhibiti mkondo.
• Reverse current per point (I_R):The small current that flows when a reverse voltage is applied. At a reverse voltage (V_R) of 5V, the maximum is specified as 100 µA. Exceeding the absolute maximum reverse voltage may cause damage.
• Average forward current per point:Upeo unaopendekezwa wa mkondo wa moja kwa moja unaoendelea kwa uendeshaji thabiti ni 13 mA. Hii ni tofauti na mkondo wa kilele unaotumika katika uendeshaji wa kuzidisha njia nyingi.
• Mkondo wa kilele wa mbele kwa kila nukta:Mkondo wa papo hapo wa juu zaidi ambao nukta moja inaweza kustahimili, umebainishwa kuwa 90 mA. Katika matumizi ya kuzidisha njia nyingi, mkondo wa papo hapo unaweza kuwa mkubwa kuliko mkondo wa wastani, lakini haupaswi kuzidi kiwango hiki cha kilele.

2.3 Absolute Maximum Ratings and Thermal Considerations

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

• Average Power Dissipation per Point:Nguvu ya juu inayoweza kutumiwa na LED moja kwa kudumu ni 33 mW. Kuzidi thamani hii kunaweza kusababisha joto kupita kiasi na kupunguza maisha ya matumizi.
• Safu ya halijoto ya kufanya kazi na kuhifadhi:Kifaa hiki kimepangwa kufanya kazi katika safu ya halijoto ya mazingira -35°C hadi +85°C. Pia kinaweza kuhifadhiwa katika safu hiyo hiyo ya halijoto.
• Kupunguzwa kwa sasa:Above 25°C, the average forward current must be linearly reduced at a rate of 0.17 mA per degree Celsius. This is a key design rule to prevent thermal runaway at higher ambient temperatures.
• Soldering Temperature:During wave soldering or reflow soldering, the temperature at 1/16 inch (approximately 1.6 mm) below the package mounting plane must not exceed 260°C for more than 3 seconds. This prevents damage to the internal chip and bonding wires.

3. Grading and Classification System

The datasheet clearly states that the device is "classified by luminous intensity." This implies the existence of a grading process.

• Luminous Intensity Grading:Baada ya utengenezaji, skrini moja-moja hupimwa kulingana na mwanga unaotolewa uliopimwa na kugawanywa katika viwango tofauti. Hii inahakikisha kwamba wateja wanapata bidhaa zenye kiwango cha mwangaza sawa. Maelezo ya uainishaji hutoa thamani ya chini/ya kawaida/ya juu (1650/3400 µcd), lakini dondoo hili halielezi kwa kina msimbo au kategoria maalum ya kiwango. Kwa kweli, habari za kuagiza hutaajia kiwango cha nguvu kinachohitajika.
• Kugawanya urefu wa wimbi/rangi:Ingawa kugawanya kwa urefu wa wimbi hakutajwi wazi katika maelezo haya ya uainishaji, wazalishaji wa LED kwa kawaida hupanga vifaa kulingana na urefu wa wimbi kuu au wa kilele ili kuhakikisha usawa wa rangi, hasa katika skrini zenye vitengo vingi. λ_p(621 nm) na λ_dThamani halisi ya kawaida ya (615 nm) inaonyesha kuwa nyenzo za AlInGaP zina usawa mzuri wa asili wa rangi.

4. Performance Curve Analysis

Mwongozo unataja "Mikunjo ya Kawaida ya Umeme/Optiki". Ingawa chati maalum haijatolewa katika maandishi, tunaweza kudhani yaliyomo na maana yake ya kawaida.

• Forward Current vs. Forward Voltage (I_F-V_F) Curve:This graph shows the nonlinear relationship between the current through an LED and the voltage across its terminals. It is crucial for designing a correct drive circuit. The curve will display a "knee" voltage (typically around 2.6V), beyond which the current increases rapidly with a small increase in voltage.
• Luminous Intensity vs. Forward Current (I_V-I_F) Curve:This graph illustrates how light output increases with drive current. It is typically linear within a certain range but saturates at very high currents. It helps determine the operating point for the desired brightness.
• Luminous Intensity vs. Ambient Temperature (I_V-T_A) Curve:Mchoro huu unaonyesha kupungua kwa mwanga unaotolewa kadiri joto la kiungo cha LED linapanda. Hupima athari ya kupunguzwa kwa joto, jambo muhimu kwa matumizi yanayofanya kazi katika mazingira ya joto la juu.
• Mkunjo wa usambazaji wa wigo:Grafu ya uhusiano kati ya nguvu ya jamaa na urefu wa wigo, inayoonyesha mkunjo wa umbo la kengele unaozingatia 621 nm na upana wa nusu ya 18 nm.

5. Taarifa za Mitambo na Ufungaji

5.1 Vipimo vya Kimwili

The character height of this display is 0.7 inches, equivalent to 17.22 mm. The package dimension drawing (referenced but not shown in the text) will detail the overall length, width, height, pin pitch, and segment arrangement. Unless otherwise specified, the tolerance for all dimensions is defined as ±0.25 mm (0.01 inch). This level of precision is crucial for mechanical fit on a printed circuit board (PCB).

5.2 Pin Connections and Internal Circuitry

Kifaa hiki kina pini 12. Ufafanuzi wa pini ni wazi: Pini 1: Anodi ya safu ya 1, Pini 2: Kathodi ya safu mlalo ya 3, Pini 3: Anodi ya safu ya 2, na kadhalika. Mchoro wa mzunguko wa ndani unaonyesha safu mlalo zina usanidi wa kathodi ya pamoja. Hii inamaanisha kila moja ya safu mlalo 7 imeunganishwa kwenye kathodi ya LED zote 5 katika safu mlalo hiyo. Waya za safu 5 zimeunganishwa kwenye anodi ya LED katika kila safu. Mpangilio huu wa matriki huruhusu udhibiti wa nukta 35 huru (5x7) kwa kutumia pini 12 tu (5+7) kupitia mbinu ya multiplexing.

5.3 Polarity Identification

Ingawa maandishi hayajaonyesha wazi, nambari za pini na mchoro wa ndani wa mzunguko hutoa maelezo muhimu yanayohitajika kwa uchambuzi wa upeo. Jedwali la ufafanuzi wa pini ni mwongozo mkuu wa kuunganisha anode na cathode kwa usahihi. Kuunganisha vibaya kwa upeo (kutumia mkazo mzuri kwa cathode) kutaizuwa LED kuwaka, na ikiwa voltage itazidi kiwango cha voltage ya nyuma (5V), inaweza kuharibu.

6. Welding and Assembly Guide

The key guideline provided is the soldering temperature profile: the temperature measured 1.6 mm below the package body must not exceed 260°C for more than 3 seconds. This is a standard guideline for wave soldering or reflow soldering processes. For manual soldering, a temperature-controlled soldering iron should be used, and contact time with the pins should be minimized to prevent heat conduction along the pins and damage to the internal chip. Proper electrostatic discharge (ESD) precautions should be observed during handling and assembly to prevent damage to semiconductor junctions.

7. Mapendekezo ya Matumizi

7.1 Mandhari ya Kawaida ya Matumizi

Kutokana na muundo wake wa gridi ya alama 5x7 unaofaa kwa kutengeneza herufi na nambari, LTP-747KA inafaa kabisa kwa matumizi yanayohitaji usomaji wazi wa herufi moja. Mifano ni pamoja na:

• Paneli za udhibiti wa viwanda na vionyeshi vya vyombo.
• Vifaa vya Uchunguzi na Upimaji.
• Vifaa vya matumizi ya kaya, kama vile tanuri ya microwave, mashine ya kuosha nguo, au vifaa vya sauti.
• Vituo vya mauzo na vionyeshi vya taarifa za msingi.
• Educational kits for learning microcontrollers and multiplexed displays.

7.2 Mazingatio ya Ubunifu

• Mzunguko wa kuendesha:Inahitaji microcontroller au IC maalum ya kiendesha maonyesho kwa ajili ya kuzidisha safu na nguzo. Kiendesha lazima kiweze kutoa/kunyonya mkondo wa kilele unaohitajika kwa safu na nguzo kwa mtiririko huo (kulingana na masharti ya majaribio, hadi 32mA kwa kila nukta, lakini muundo unapaswa kurejelea viwango vya juu kabisa).
• Kikomo cha mkondo:Kila anode (safu) laini lazima itumie upinzani wa kikomo wa nje kuweka mkondo wa mbele na kulinda LED. Thamani ya upinzani hutumia fomula R = (V_{Ugavi wa umeme}- V_F) / I_F Computation. The peak current (I_P) must be considered for use in multiplexed computation.
• Thermal Management:In high ambient temperature environments or high-brightness applications, ensure the average current is derated as specified (0.17 mA per degree Celsius above 25°C). Adequate spacing on the PCB aids natural convection cooling.
• Perspective:The datasheet claims to have a "wide viewing angle," which is highly beneficial for applications where the display might be viewed from off-axis positions.

8. Ulinganisho wa Kiufundi na Tofauti

Ingawa hakuna kulinganisha moja kwa moja na aina nyingine zilizotolewa, kulingana na maelezo yake ya uainishaji, sababu muhimu za utofautishaji wa LTP-747KA ni pamoja na:

• Teknolojia ya nyenzo (AlInGaP):Ikilinganishwa na LED za zamani za GaAsP au GaP, AlInGaP hutoa ufanisi bora, utulivu bora wa joto na mwangaza bora zaidi, na hivyo kufanikisha madai ya "mwangaza wa juu na tofauti kubwa ya rangi".
• Dot Matrix vs. Segment Display:The 5x7 dot matrix offers greater flexibility than the standard 7-segment display because it can display the full ASCII character set, symbols, and simple graphics, rather than just numbers and a few letters.
• Intensity Classification:Kugawanya kiwango cha mwanga ni utendaji wa thamani ya ziada kwa matumizi yanayohitaji usawa kati ya vitengo mbalimbali.
• Kuimarisha tofauti ya mwanga:Bodi ya kijivu yenye nukta nyeupe ni chaguo la muundo linalolenga kuboresha tofauti ya mwanga wakati LED zimezimwa, na kufanya skrini ionekane kitaalamu na iweze kusomeka kwa urahisi chini ya hali mbalimbali za mwanga.

9. Maswali Yanayoulizwa Mara kwa Mara (Kulingana na Vigezo vya Kiufundi)

9.1 What is the difference between Peak Forward Current (90mA) and Test Condition Current (32mA)?

Peak Forward Current (90mA) is an Absolute Maximum Rating—the highest instantaneous current the LED can withstand without immediate damage. The 32mA used in luminous intensity testing is a typical operating condition measured in a multiplexed (1/16 duty cycle) system. In that case,averageMkondo wa umeme unapaswa kuwa mdogo zaidi (32mA / 16 = 2mA). Muundo lazima uhakikishe mkondo wa papo hapo unabaki chini ya 90mA, na mkondo wa wastani katika kila nukta unabaki chini ya 13mA (kuzingatia kupunguzwa kwa joto).

9.2 How to understand the 1/16 duty cycle specification?

Hii inawakilisha njia ya kawaida ya kuendesha ya kuzidisha. Ili kudhibiti safu 5 na safu mlalo 7, mbinu ya kawaida ni kuamilisha safu mlalo moja kwa wakati mmoja, na kuzizunguka haraka zote 7. Ikiwa kila safu mlalo inafunguliwa kwa muda sawa, basi muda wake wa kuamilishwa ni 1/7 ya jumla ya muda. Uwiano wa kazi ya 1/16 ni hali ya kawaida ya kupima, iliyokubaliwa na sanifu, inayoruhusu kulinganisha kati ya vielelezo tofauti, hata kama mpango wako halisi wa kuzidisha katika matumizi yako ni uwiano wa kazi ya 1/7 au 1/8.

9.3 Why is the forward voltage given as a range (minimum 2.05V, typical/maximum 2.6V)?

Voltage ya mbele (V_F) ina tofauti asilia kutokana na uvumilivu wa utengenezaji wa nyenzo za semiconductor. Muundo wa mzunguko lazima ukubaliane na safu hii. Upinzani wa kudhibiti mkondo unapaswa kutumiaThamani ya juu kabisa V_F(2.6V) ili kuhakikisha kwamba hata vifaa vyenye V_Fvya juu vinapata voltage ya kutosha kuwasha na kufikia mkondo unaohitajika. Kutumia thamani ya kawaida kwa hesabu kunaweza kuleta hatari ya kusukumwa kwa baadhi ya seli.

10. Design and Use Case Examples

Scenario:Design a single-character temperature readout display for an industrial controller operating in environments up to 50°C.

1. Character Set:A 5x7 matrix can display digits 0-9 and letters, such as "C" for degrees Celsius.
2. Driver Selection:A microcontroller with at least 12 I/O pins or a dedicated display driver IC (e.g., MAX7219) will be used to handle the multiplexing timing.
3. Hesabu ya sasa:Weka sasa ya wastani ya nukta inayohitajika kwa mwangaza mzuri. Tuchukulie tunachagua wastani wa 8mA. Katika 50°C, punguzo linatumika: Punguzo = (50°C - 25°C) * 0.17 mA/°C = 4.25 mA. Sasa ya wastani ya juu inayoruhusiwa kwenye 50°C = 13 mA - 4.25 mA = 8.75 mA. Lengo letu la 8mA limewekwa kwa usalama.
4. Hesabu ya upinzani:Kwa multiplexing ya 1/7 (safu 7), kilele cha sasa kwa kila nukta kinahitaji kufikia 8mA * 7 = 56mA ili kufikia wastani wa 8mA. Hii iko chini ya kiwango cha kilele cha 90mA. Kwa kutumia usambazaji wa umeme wa 5V na V_F(max)=2.6V, upinzani wa kikomo cha sasa ni R = (5V - 2.6V) / 0.056A ≈ 42.9Ω. Upinzani wa kawaida wa 43Ω utatumika.
5. Muundo wa PCB:The display placeholder will match the dimensional drawing. Sufficient space will be left around the package for airflow.

The LTP-747KA operates based on the principle of electroluminescence in a semiconductor p-n junction. When a forward voltage exceeding the diode's built-in potential is applied (anode positive relative to the cathode), electrons from the n-type AlInGaP layer recombine with holes from the p-type layer. This recombination event releases energy in the form of photons (light). The specific composition of the AlInGaP alloy (aluminum, indium, gallium, phosphorus) determines the semiconductor's bandgap energy, which directly dictates the wavelength (color) of the emitted light—in this case, a red-orange color of approximately 621 nm. The chip is mounted on an opaque gallium arsenide (GaAs) substrate, which helps reflect light upward, improving the overall light extraction efficiency from the top surface of the device. The 5x7 matrix is formed by individually addressable LEDs arranged in this grid pattern, controlled by an external multiplexing circuit that rapidly sequences power to the rows and columns to create the visual illusion of a stable, fully illuminated character.

12. Mielekeo ya Kiufundi na Mazingira

Teknolojia ya LED ya AlInGaP iliyotumika katika LTP-747KA ilikuwa maendeleo makubwa ikilinganishwa na nyenzo za awali za LED kama GaAsP. Ilifanya uwezekano wa mwangaza wa juu zaidi, ufanisi bora, na uthabiti bora wa joto, na kufanya LED ziweze kutumika katika anuwai pana ya matumizi ya viashiria na maonyesho. Mwenendo wa teknolojia ya maonyesho baadaye uligeukia kuelekea matriki ya nukta zenye msongamano wa juu, matriki kamili za rangi za RGB, na upitishaji mpana wa maonyesho ya LED ya kikaboni (OLED) na maonyesho ya LED midogo katika skrini zenye usahihi wa juu. Hata hivyo, maonyesho ya matriki ya nukta ya herufi na nambari ya tarakimu moja na nyingi kama muundo wa 5x7 bado yanahusika sana kwa kiolesura cha gharama nafuu, cha kuaminika, na kinachosomeka kwa urahisi katika mazingira ya viwanda, vifaa, na vyombo vya kupimia ambapo uwezo kamili wa picha hauhitajiki. Kanuni za msingi za kuendesha—uzidishaji na udhibiti wa mkondo—bado ndio msingi wa muundo wa maonyesho ya LED bila kujali kiwango au teknolojia.

AlInGaP LED technology, as used in the LTP-747KA, represented a significant advancement over earlier LED materials like GaAsP. It enabled higher brightness, improved efficiency, and better temperature stability, making LEDs viable for a wider range of indicator and display applications. The trend in display technology has since moved towards higher-density dot matrices, full-color RGB matrices, and the widespread adoption of organic LED (OLED) and micro-LED displays for high-resolution screens. However, single and multi-digit alphanumeric dot matrix displays like the 5x7 format remain highly relevant for cost-effective, reliable, and easily readable interfaces in industrial, appliance, and instrumentation contexts where full graphical capability is not required. The underlying drive principles—multiplexing and current control—remain fundamental to LED display design regardless of the scale or technology.