LTP-2257KA 5x7 Dot Matrix LED Display Datasheet - 1.97-Inch Character Height - AlInGaP Red Orange - Technical Documentation

1. Mchanganuo wa Bidhaa

LTP-2257KA ni moduli ya kuonyesha herufi moja, ya nambari na herufi, iliyoundwa kwa matumizi yanayohitaji matokeo ya herufi wazi na ya kuaminika. Kazi yake kuu ni kuwasilisha data kwa njia ya kuona kupitia gridi ya nukta inayoundwa na diodi zinazotoa mwanga (LED) zinazoweza kushughulikiwa kwa kujitegemea, kwa kawaida herufi zilizosimbwa kwa ASCII au EBCDIC. Kifaa hiki kimeundwa kwa ajili ya kuunganishwa katika mifumo inayohitaji madhubuti mambo muhimu ya utendaji kama vile matumizi ya nguvu ya chini, uaminifu wa hali ngumu, na pembe pana ya mtazamo.

The primary markets for this component include industrial control panels, instrumentation, point-of-sale terminals, basic information displays, and embedded systems requiring simple, robust character readouts. Its stackable design allows for the creation of multi-character displays in a horizontal orientation, providing flexibility for displaying words or numbers.

Its core technical advantage lies in the use of Aluminum Indium Gallium Phosphide (AlInGaP) semiconductor material for the LED chips. This material system is renowned for generating high-efficiency light emission within the red to amber-orange spectral range, providing good visibility. The display features a black panel, which creates high contrast with the illuminated white light dots, significantly enhancing readability under various ambient lighting conditions.

2. Ufafanuzi wa Vipimo vya Kiufundi

Sehemu hii inachambua kwa kina na kwa uwazi vigezo muhimu vya umeme, vya macho na vya kimwili vilivyobainishwa katika hati ya vipimo.

2.1 Tabia za Mwangaza na Optics

Utabiri wa mwanga ndio kiini cha utendaji wa skrini. Vigezo muhimu hupimwa chini ya hali zilizosanifishwa za majaribio (Ta=25°C) ili kuhakikisha uthabiti.

• Nguvu ya wastani ya mwanga (I_V):Anuwai kutoka kwa thamani ya chini ya 2100 µcd hadi thamani ya juu ya 5000 µcd, na inamaanisha thamani ya kawaida. Nguvu hiyo iko kwenye I_pMeasured for each light spot under pulse drive conditions of =32mA and a duty cycle of 1/16. A 1/16 duty cycle is typical for multiplexed matrix driving, where each row is active only for a fraction of the time. The sensor used approximates the CIE photopic luminosity function, ensuring the measurements are relevant to human eye sensitivity.
• Peak Emission Wavelength (λ_p):The typical value is 621 nanometers (nm). This represents the wavelength at which the optical power output is greatest. It lies in the red-orange region of the visible spectrum.
• Dominant Wavelength (λ_d):615 nm. This is the single wavelength perceived by the human eye as matching the color of the LED's output. It is slightly lower than the peak wavelength, a common occurrence due to the shape of the emission spectrum.
• Upanaaji wa nusu ya mstari wa wigo (Δλ):Takriban 18 nm. Kigezo hiki kinafafanua upanaaji wa bendi ya mwanga unaotolewa, hasa kurejelea upanaaji wa mkunjo wa wigo katika nusu ya nguvu yake ya juu zaidi. Thamani ya 18 nm inaonyesha hii ni chanzo cha mwanga cha monokromatiki chenye bendi nyembamba, ambacho ni sifa ya AlInGaP LED, na hutoa rangi iliyojaa.
• Ulinganisho wa nguvu ya mwanga unaolingana (I_V-m):Upeo wa 2:1. Hii ni kigezo muhimu cha kuonyesha usawa. Inabainisha kuwa mwanga wa nukta yoyote moja hauzidi mara mbili mwanga wa nukta nyingine yoyote ndani ya moduli sawa ya kuonyesha. Hii inahakikisha mwangaza sawa wa sehemu zote za herufi.

2.2 Tabia za Umeme

Vigezo vya umeme vinabainisha mahitaji ya kiunganishi na usambazaji wa nguvu kwa kifaa.

• Voltage ya mbele (V_F):Katika mkondo wa majaribio (I_F) ya 20mA, anuwai ya kila nukta ya mwanga ni kutoka 2.05V (kidogo) hadi 2.6V (kubwa zaidi). Hii ni punguzo la voltage kwenye LED inapowashwa. Wabunifu lazima wahakikisha mzunguko wa kuendesha unaweza kutoa voltage hii. Thamani ya kawaida haijatajwa, lakini iko ndani ya anuwai hii.
• Mkondo wa nyuma (I_R):At a reverse voltage (V_R) of 15V, the maximum is 100 µA. This is the small leakage current that flows when the LED is reverse-biased. It is usually negligible in operation but must be considered in circuit protection design.
• Average forward current per light point:The rated average current is 13 mA. However, above 25°C, a linear derating factor of 0.17 mA/°C must be applied. This means that as the ambient temperature increases, the allowable maximum average current must be reduced to prevent overheating and premature failure. For example, at 85°C, the maximum average current is: 13 mA - [0.17 mA/°C * (85-25)°C] = 13 - 10.2 = 2.8 mA.

2.3 Absolute Maximum Ratings

These are stress limits that must not be exceeded under any conditions, even momentarily. Operation beyond these limits may cause permanent damage.

• Average Power Consumption per Spot:Upeo wa 36 mW. Hii ni zao la wastani wa mkondo wa mbele na voltage ya mbele.
• Upeo wa mkondo wa mbele kwa kila nukta ya mwanga:Upeo wa 100 mA. Hii ndiyo mkondo wa juu zaidi wa papo hapo unaoruhusiwa, kwa kawaida unahusishwa na mipigo mifupi sana katika mpango wa multiplexing.
• Reverse voltage per light point:Maximum 5 V. Exceeding this value may cause junction breakdown.
• Operating and storage temperature range:-35°C to +85°C. The device is rated for the industrial temperature range.
• Soldering temperature:Maximum 260°C for up to 3 seconds, measured 1.6mm (1/16 inch) below the seating plane. This is critical for wave soldering or reflow soldering processes.

3. Grading and Classification System

The datasheet clearly states that the device is "classified by luminous intensity." This indicates that the units are sorted or "binned" based on their measured light output. The luminous intensity range (2100-5000 µcd) likely represents the distribution across multiple bins. Manufacturers typically group LEDs into tighter intensity ranges (e.g., 2100-3000 µcd, 3000-4000 µcd, 4000-5000 µcd). This allows customers to select bins according to their specific brightness uniformity requirements. For multi-unit displays, using LEDs from the same intensity bin is crucial for achieving a uniform appearance. The datasheet does not specify binning for forward voltage or wavelength, but the provided min/max ranges for V_Fand λ_pdefine the overall distribution.

4. Performance Curve Analysis

Mwongozo unarejelea "Mikunjo ya Kawaida ya Tabia ya Umeme/Optiki". Ingawa michoro maalum haijatolewa katika maandishi, tunaweza kukisia yaliyomo na maana yake ya kawaida.

• Nguvu ya Mwanga ya Jamaa dhidi ya Sasa ya Mbele (Mkunjo wa I-V):Grafu hii itaonyesha jinsi pato la mwanga linavyobadilika kadri mkondo wa kuendesha unavyoongezeka. Kwa kawaida, uhusiano sio wa mstari, na katika mikondo ya juu sana, ufanisi hupungua kwa sababu ya athari za joto. Sehemu ya mtihani wa msukumo wa 32mA kwa uwezekano mkubwa iko katika sehemu inayofanya kazi ya mstari ya mkunjo huu.
• Voltage ya mbele dhidi ya mkondo wa mbele:Mkunjo huu unaonyesha sifa za I-V za diode. Voltage huongezeka kwa kiwango cha logarithmic kadri mkondo unavyoongezeka. V_Fni sehemu kwenye mkunjo huu.
• Mwangaza wa jamaa dhidi ya joto la mazingira:Hii ni mkunjo muhimu kwa kuelewa utendaji wa joto. Pato la mwanga la LED kwa kawaida hupungua kadri joto la kiungo kinavyoongezeka. Kipengele cha kupunguza cha sasa ya moja kwa moja kilichobainishwa kinahusiana moja kwa moja na kudhibiti athari hii ya joto ili kudumisha utendaji na uaminifu.
• Usambazaji wa wigo:Grafu ya nguvu ya jamaa dhidi ya urefu wa wimbi, inayoonyesha kilele cha takriban 621nm, na upana wa nusu ya kilele (FWHM) wa takriban 18nm.

5. Taarifa za Mitambo na Ufungashaji

Kifaa hiki ni kipengele cha kupitia-shimo, kinachotumia umbo la kawaida la DIP (Dual In-line Package), kinachofaa kwa usakinishaji wa PCB.

• Dot matrix height:The defining physical characteristic is a character height of 1.97 inches (50.15 mm). This is a large-format display designed specifically for long-distance viewing.
• Package size:The datasheet includes detailed dimensional drawings. All dimensions are in millimeters, with a standard tolerance of ±0.25 mm unless otherwise specified. This drawing is crucial for PCB pad design and ensuring proper fit within the enclosure.
• Pin Connections:The device has 12 pins arranged in a single row.
  • Pins 1-7: Correspond to cathode rows 1 to 7. In a typical matrix configuration, these would be the scan lines.
  • Pini 8-12: Yanahusiana na safu wima za anode 5 hadi 1 (kumbuka mpangilio wa nyuma: pini 8 ni safu wima 5, pini 12 ni safu wima 1). Hizi zitakuwa mistari ya data.
• Mchoro wa ndani wa saketi:Mchoro uliotolewa unaonyesha usanidi wa kawaida wa matriki ya 5x7. Kila LED (nukta ya mwanga) iko kwenye makutano ya safu ya anode na safu ya cathode. Ili kuangazia nukta maalum ya mwanga, ni lazima kuendesha laini yake inayolingana ya anode kuwa ya juu (voltage chanya), wakati huo huo kuendesha laini yake ya cathode kuwa ya chini (ardhi). Mpangilio huu wa matriki hupunguza kiwango cha pini za kuendesha zinazohitajika (12, badala ya 35 zinazohitajika kwa kushughulikia nukta za mwanga kwa pekee).
• Kitambulisho cha polarity:Jedwali la ufafanuzi wa pini linaonyesha wazi viunganisho vya anode na cathode. Mwisho mmoja wa kifurushi unaweza kuwa na ufa au alama ili kuonyesha mwelekeo wa pini 1.

6. Mwongozo wa Uchomaji na Usanikishaji

Viwango muhimu vya usanikishaji vinavyotolewa vinakusudiwa kwa mchakato wa uchimbaji.

• Vigezo vya Reflow Soldering/Wave Soldering:Absolute Maximum Ratings specify that the device can withstand a maximum soldering temperature of 260°C for up to 3 seconds. This measurement is taken 1.6mm below the mounting plane (i.e., at the PCB level), not on the component body. This is the standard rating for leaded components and is compatible with typical wave soldering profiles. For reflow soldering using lead-free solder (which has a higher melting point), the temperature profile must be carefully controlled to ensure the component body temperature does not exceed the maximum storage temperature of 85°C for an extended period, even if the leads briefly reach 260°C.
• Hand Soldering:If hand soldering must be performed, a temperature-controlled soldering iron should be used. The contact time per lead should be minimized, ideally less than 3 seconds, to prevent heat conduction along the lead and damage to the internal wire bonds or epoxy.
• Cleaning:Hakuna maelezo maalum ya usafishaji yaliyotolewa. Inawezekana kutumia isopropanol ya kawaida au kiondoaji cha flux iliyoidhinishwa, lakini unapaswa kuepuka kutumia viyeyusho vyenye nguvu kwani vinaweza kuharibu paneli ya plastiki au alama.
• Masharti ya Uhifadhi:Kifaa kinapaswa kuhifadhiwa katika anuwai maalum ya joto ya -35°C hadi +85°C, katika mazingira yaliyokauka na yasiyo na umande. Inashauriwa kuhifadhi vipengele katika mfuko wao asili wa kuzuia unyevunyevu kabla ya matumizi, ili kuzuia unyevunyevu ambao unaweza kusababisha "popcorn" wakati wa kuunganisha.

7. Mapendekezo ya Utumiaji

7.1 Matumizi ya Kawaida ya Kifani

• Paneli ya Kudhibiti Viwanda:Onyesha sehemu iliyowekwa, thamani ya mchakato (joto, shinikizo, kasi), msimbo wa makosa au hali ya mashine.
• Vifaa vya Uchunguzi na Upimaji:Onyesha usomaji wa nambari wa multimeter, chanzo cha umeme au kizazi cha ishara.
• Bidhaa za Umeme za Matumizi ya Kawaida (Kijadi):Saa, vihesabuji vya msingi, au skrini za vifaa vya nyumbani.
• Uundaji wa Mfano wa Mfumo Ulioingizwa:To provide simple and direct output for microcontrollers (such as Arduino, PIC) to display debugging information or user prompts.
• Stacking multi-character displays:By placing multiple LTP-2257KA modules side by side, words, numbers, or simple scrolling messages can be created for basic information boards or signs.

7.2 Mambo ya Kuzingatia katika Ubunifu

• Drive Circuit:A dedicated LED driver IC or a microcontroller GPIO pin with a current-limiting resistor is required. Due to the matrix configuration, a multiplexing (scanning) scheme must be employed. The driver must source current to the anode columns and sink current from the cathode rows. In multiplexing timing calculations, the peak current (100mA) per pixel and average current derating must be observed.
• Current Limitation:Each anode column or cathode row (depending on the drive topology) must use an external resistor to set the operating current. Its value is determined based on the supply voltage (V_CC), the LED forward voltage (V_F) na mkondo unaohitajika (I_F) hesabu. Kwa mfano, kwa kutumia chanzo cha umeme cha 5V, V_Fni 2.3V, lengo I_Fni 20mA: R = (5V - 2.3V) / 0.02A = 135 ohms. Upinzani wa kawaida wa 150 ohms utakuwa unaofaa.
• Usimamizi wa joto:Ingawa kifaa hiki kinatumia nguvu kidogo, ni muhimu kufuata mkunjo wa kupunguza mkondo wa mbele katika hali ya joto la juu la mazingira. Ikiwa skrini imefungwa, hakikisha kuna mtiririko wa hewa wa kutosha. Matumizi ya wastani ya nguvu kwa kila nukta ya mwanga (kiwango cha juu cha 36mW) hubadilishwa kuwa jumla ya matumizi ya juu ya nguvu kwa herufi nzima iliyowashwa, ambayo inapaswa kuzingatiwa katika muundo wa joto wa PCB.
• Pembe ya Mtazamo:Sifa ya "Pembe Pana ya Mtazamo" ni muhimu, lakini kwa usomaji bora zaidi, skrini inapaswa kusakinishwa ikikabili mwangalizi mkuu. Muundo wa Paneli Nyeusi/Nukta za Mwanga Nyeupe hutoa tofauti nzuri katika pembe nyingi.

8. Technical Comparison and Differentiation

Ikilinganishwa na teknolojia zingine za kuonyesha zilizopatikana wakati wa uzinduzi wake (2000), LTP-2257KA inatoa faida maalum:

• Ikilinganishwa na taa za incandescent au skrini za mwanga wa fluorescent kwenye utupu (VFD):LED ni vifaa thabiti, vinazalisha uaminifu wa juu zaidi, uwezo wa kukabiliana na mshtuko/mshtuko, maisha marefu zaidi (kwa kawaida mamia ya maelfu ya masaa) na voltage ya chini ya uendeshaji/matumizi ya nguvu. Pia hazihitaji filament ya kupokanzwa au voltage ya juu.
• Ikilinganisha na LCD za awali:LED ni vifaa vinavyojitokeza mwanga wenyewe, maana yake vinazalisha mwanga wenyewe, hivyo kuwaweka wazi kuonekana katika hali ya mwanga mdogo au giza bila taa ya nyuma. Zina anuwai pana ya joto la uendeshaji na wakati wa kukabiliana wa haraka. Hata hivyo, hutumia nguvu zaidi kuliko LCD zinazojitokeza, na hazifai kwa picha ngumu.
• Ikilinganisha na teknolojia nyingine za LED:Ikilinganisha na GaAsP au GaP ya zamani, nyenzo za AlInGaP hutoa ufanisi bora na usafi wa rangi ulio bora (nyekundu-machungwa uliojaa) kwa mkondo maalum wa kuendesha. Muundo maalum wa 5x7 na urefu mkubwa wa inchi 1.97, unalenga matumizi yanayohitaji usomaji rahisi wa herufi kutoka umbali.

9. Frequently Asked Questions (Based on Technical Parameters)

Q: Can I drive all light spots simultaneously with a constant DC current?
A: Technically possible, but extremely inefficient. If all 35 light spots are lit, it will exceed the average power rating. The standard and recommended method is to use multiplexing, where light spots are lit one row (or column) at a time at a high frequency, creating the visual illusion of a stable display while significantly reducing the average current.

Q: What is the difference between peak wavelength and dominant wavelength?
A: Peak wavelength is the position where the LED emits the maximum optical power. Dominant wavelength is the single wavelength perceived by the human eye that matches the LED's color. Due to the asymmetry of the LED emission spectrum, they are usually close but not identical. Dominant wavelength is more relevant to color perception.

Q: The forward voltage is 2.05-2.6V. Can I run it with a 3.3V logic supply?
A: Yes, absolutely. A 3.3V supply is sufficient to forward bias the LED. You need to recalculate the current-limiting resistor value based on the lower supply voltage (e.g., R = (3.3V - 2.3V) / 0.02A = 50 ohms).

Q: What does "1/16 duty cycle" mean in the luminous intensity test conditions?
Jibu: Hii inamaanisha kuwa LED inaendeshwa kwa msukumo wa mkondo wa 32mA, lakini msukumo huo unafanya kazi tu katika 1/16 ya muda wa mzunguko mzima. Ukubwa wa mwanga unaopimwa ni wastani katika mzunguko mzima. Hii inalinganisha na masharti ya mpango wa kuendesha kwa njia ya multiplexing ya 1:16 (mfano, safu 7 + nafasi tupu 9 = nafasi 16 za wakati).

10. Mifano Halisi ya Usanifu na Matumizi

Kesi: Kujenga onyesho rahisi la voltamita yenye tarakimu 4.Mhandisi anahitaji kuonyesha voltage kuanzia 0.000 hadi 9.999 volts kwenye paneli. Wao wameamua kutumia moduli nne za LTP-2257KA zilizopangwa mlolongo usio na usawa.

1. Ubunifu wa Saketi:Kikoa kidogo chenye ADC kinasoma voltage. Firmware inabadilisha usomaji kuwa tarakimu nne za desimali. Bandari za I/O za kikoa kidogo, pamoja na transistor tofauti au IC maalum ya kuendesha multiplex (kama MAX7219), zimewekwa ili kuchanganua skrini hizi nne. Safu ya cathode ya kila skrini imeunganishwa kwa sambamba, wakati safu ya anode ya kila tarakimu inadhibitiwa peke yake. Hii inatengeneza matriki ya tarakimu 4 x safu 7.
2. Current Setting:Using a 5V power supply and desiring a bright display, they selected an average current of 15mA per light point. Considering multiplexing across 4 bits and 7 lines (when all light points are on, the effective duty cycle for each point is 1/28), the peak pulse current during its active time slot would be higher (e.g., 15mA * 28 = 420mA), but this must be checked against the 100mA peak current rating. Therefore, they need to adjust the timing or use a lower average current to keep the peak current within specifications.
3. Thermal Considerations:Hii paneli inatumika katika mazingira ya maabara (25°C). Hakuna haja ya kuwa na wasiwasi kuhusu kupunguzwa kwa sasa ya wastani hapa. Walakini, wanahakikisha kuwa PCB ina safu ya ardhi ili kusaidia kutawanya joto la mzunguko wa kuendesha.
4. Matokeo:Bidhaa ya mwisho inaonyesha usomaji wa tarakimu 4 wenye uwazi, mkali na pembe nzuri ya mtazamo, ikikidhi mahitaji ya vifaa vya dawati.

11. Kanuni za Uendeshaji

LTP-2257KA inafanya kazi kulingana na kanuni ya msingi ya Diodi zinazotoa Mwanga (LED) zilizopangwa kwenye matriki isiyo na nguvu. Kila moja ya nukta 35 za mwanga zinazounda gridi ya 5x7 ni chip ya kujitegemea ya LED ya AlInGaP. Wakati voltage ya upendeleo mzuri inayozidi uwezo wa kiungo cha diodi (takriban 2V) inatumika kwenye jozi maalum ya anode (safu) na cathode (safu mlalo), mkondo unapita kwenye LED ya makutano hayo. Mkondo huu husababisha elektroni na mashimo kuchanganyika ndani ya eneo lenye shughuli la semikondukta, na kutolea nishati kwa njia ya fotoni – yaani, mwanga, ambao urefu wa wimbi lake ni sifa ya nyenzo za AlInGaP (nyekundu-machungwa).

矩阵组织是一种巧妙的互连方法。不是使用35根单独的导线，而是将垂直列中所有LED的阳极连接在一起，将水平行中所有LED的阴极连接在一起。要点亮单个光点，其特定的列被驱动为正，其特定的行被驱动为地。要显示一个图案（如字符），扫描算法会快速遍历各行（或各列），依次为每一行打开相应的列驱动器。在足够高的频率下（通常>100Hz），视觉暂留使整个字符看起来稳定地发光。

12. Mwelekeo wa Teknolojia na Mazingira

LTP-2257KA represents a mature and well-established display technology. At the time of its release, dot-matrix LED displays were the mainstream solution for alphanumeric output. The shift from older materials like GaAsP to AlInGaP was a significant trend, offering higher efficiency and better color.

Subsequent trends have shifted towards:
Surface Mount Device (SMD) Packaging:Nearly all modern equivalents are of the SMD type, enabling smaller, automated assembly.
Higher Density and Full-Matrix Displays:The basic 5x7 format has largely been replaced by larger dot matrix modules (e.g., 8x8, 16x16) and full-graphic panels capable of displaying arbitrary shapes and text in multiple fonts.
Integrated Controller:Modern LED matrix modules typically integrate drivers, memory, and communication interfaces (such as I2C or SPI) on a single board, greatly simplifying the design process for engineers.
Alternative Technologies:Kwa matumizi mengi yanayohitaji utoaji wa herufi rahisi, skrini za LCD zenye matumizi ya nguvu chini (zilizo na au bila taa ya nyuma) na OLED zimekuwa maarufu zaidi, hasa pale ambapo matumizi ya nguvu, unene, au uwezo wa michoro ni vipaumbele.

Licha ya mielekeo hii, skrini za LED zenye mashimo ya kupenyeza kama LTP-2257KA bado zina umuhimu katika mazingira ya elimu, miradi ya wapenzi, matengenezo ya vifaa vya zamani, na katika matumizi maalum ya viwanda ambapo unyenyekevu, uthabiti, mwangaza mkubwa, na anuwai pana ya joto ni faida za kufunga maamuzi.