LTC-4724JD 0.4-Inch Three-Digit Seven-Segment LED Display Datasheet - Character Height 10.0mm - Forward Voltage 2.6V - Super Red 639nm - Technical Documentation

1. Uhakiki wa Bidhaa

The LTC-4724JD is a compact, high-performance three-digit seven-segment display module, specifically designed for applications requiring clear and bright digital readouts. Its core function is to intuitively display three digits (0-9) through independently addressable LED segments. The design focus of this device is to achieve high readability and reliability in various electronic systems.

This display is primarily used in instrumentation, control panels, testing equipment, and consumer electronics, applications that require compact multi-digit numeric output. It serves as a direct interface between digital logic circuits and the user, converting electrical signals into visible numerals. The use of AS-AlInGaP (aluminum indium gallium phosphide) LED chips grown on a GaAs substrate is its key technical feature. This material system is renowned for its high efficiency and excellent color purity within the red-orange to red spectral range, directly contributing to the display's high brightness and high contrast.

The display features a gray panel with white segment identifiers. This combination is designed to maximize contrast and readability under various lighting conditions when the red LEDs are illuminated. Its design prioritizes a continuous, uniform appearance across all segments and digits, eliminating visual gaps or inconsistencies that could hinder rapid data interpretation.

2. Uchambuzi wa kina wa Vigezo vya Kiufundi

2.1 Tabia za Fotometri na Optics

Optical performance is central to the display's functionality. Key parameters, measured at an ambient temperature (Ta) of 25°C, define its visual output.

• Average Luminous Intensity (I_V):At a forward current (I_F) of 1 mA, it ranges from a minimum of 200 µcd to a typical value of 650 µcd. This parameter quantifies the perceived brightness of the illuminated segment. The luminous intensity classification mentioned in the characteristics indicates that devices may be binned or screened based on measured output to ensure consistency within production batches.
• Peak emission wavelength (λ_p):639 nanometers (nm). This is the wavelength at which the LED emits maximum optical power, located in the ultra-red region of the visible spectrum.
• Dominant wavelength (λ_d):631 nm. This is the single wavelength perceived by the human eye as the closest match to the color of the emitted light, which is crucial for color definition.
• Spectral line half-width (Δλ):20 nm. This indicates the spectral purity or bandwidth of the emitted light. A narrower half-width typically means more saturated and purer color.
• Luminous intensity matching ratio (I_V-m):Upeo wa 2:1. Hii inabainisha tofauti inayoruhusiwa ya mwangaza kati ya sehemu tofauti ndani ya kifaa kimoja, kuhakikisha usawa wa kuona.

Vipimo vyote vya nguvu ya mwanga hufanywa kwa kutumia sensor na kichujio kilichokalibriwa kwa utendakazi wa mwangaza wa kuona wa CIE, ambao unakaribia usikivu wa wigo wa jicho la binadamu chini ya hali ya mwanga ya kawaida.

2.2 Tabia za Umeme na Viwango vya Juu Kabisa

Kufuata vikwazo hivi ni muhimu kwa maisha ya kifaa na kuzuia hitilafu mbaya.

• Sasa ya mwendelezo ya mbele kwa kila sehemu (I_F):Ya juu hadi 25 mA kwa 25°C. Hii ndiyo sasa ya moja kwa moja inayoweza kutumiwa kwa sehemu moja kwa mfululizo. Kipimo hiki kinapungua kwa mstari kwa 0.33 mA/°C kwa joto la juu kuliko 25°C, ikimaanisha sasa inayoruhusiwa hupungua kadri halijoto ya mazingira inavyoongezeka, ili kudhibiti joto.
• Sasa ya kilele ya mbele kwa kila sehemu:Upeo wa 90 mA. Hii inaruhusiwa tu chini ya hali ya msukumo (msukumo wa 1 kHz, uwiano wa kazi 10%), ili kufikia mwangaza wa papo hapo wa juu bila kupata joto kupita kiasi.
• Voltage per segment (V_F):Typical value 2.6V, maximum 2.6V at I_F=20mA. This is the voltage drop when the LED is conducting. The designer must ensure the driving circuit can provide sufficient voltage.
• Reverse voltage per segment (V_R):Maximum 5V. Exceeding this value may damage the LED junction.
• Reverse current per segment (I_R）：Maximum 100 µA at V_R=5V. This is the small leakage current flowing when the LED is reverse biased.
• Power dissipation per segment:Maximum 70 mW. This is the thermal power limit converted to heat within a single segment.

2.3 Vigezo vya Joto na Mazingira

Mipaka ya uendeshaji wa kifaa inafafanuliwa na anuwai ya joto.

• Anuwai ya joto la uendeshaji:-35°C hadi +85°C. Skrini imebuniwa kufanya kazi kwa kawaida ndani ya anuwai hii ya joto la mazingira.
• Anuwai ya joto la uhifadhi:-35°C hadi +85°C. Kifaa kinaweza kuhifadhiwa bila kufanya kazi ndani ya mipaka hii bila kuharibika.
• Joto la kuunganishia:Wakati wa mchakato wa kuunganishia kwa kuyeyusha tena, kifurushi kinaweza kustahimili joto la kilele la 260°C kwa umbali wa inchi 1/16 (takriban 1.6mm) chini ya ndege ya usakinishaji kwa sekunde 3.

3. Binning and Classification System

The datasheet explicitly states that the device is "classified by luminous intensity." This implies a post-production binning process. While this excerpt does not provide specific binning codes, typical classification for such displays involves screening units based on luminous intensity measured at a standard test current (e.g., 1mA or 20mA). This ensures designers procuring multiple displays can expect all units in their product to have a consistent brightness level, thereby maintaining a uniform appearance on the final panel. Forward voltage (V_F) matching ratio may also be part of the complete binning specification, though not detailed here.

4. Uchambuzi wa Mkunjo wa Utendaji

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

• Forward Current vs. Forward Voltage (I-V Curve):Shows an exponential relationship, crucial for designing current-limiting circuits. This curve would indicate the turn-on voltage and how V_Fvaries with I_F.
• Relative Luminous Intensity vs. Forward Current:Inaonyesha jinsi pato la mwanga linavyoongezeka kwa kuongezeka kwa mkondo wa kuendesha, kwa kawaida huwa na uhusiano wa takriban mstari hadi kufikia hatua fulani, baada ya hapo ufanisi hupungua.
• Uwiano wa nguvu ya mwanga dhidi ya joto la mazingira:Inaonyesha kupungua kwa pato la mwanga kwa kuongezeka kwa joto. Ufanisi wa AlInGaP LED kwa kawaida hupungua kwa kasi kwa kuongezeka kwa joto.
• Usambazaji wa wigo:Grafu ya uwiano wa nguvu dhidi ya urefu wa wimbi, inayoonyesha kilele cha 639nm na upana wa nusu ya 20nm.

Mipaka hii ni muhimu sana kwa kuboresha hali ya kuendesha, kuelewa athari za joto, na kutabiri utendaji katika mazingira halisi ya matumizi.

5. Taarifa za Mitambo na Ufungaji

5.1 Vipimo vya Kimwili na Umbo

Kifaa hiki kimeelezewa kama onyesho la "urefu wa herufi inchi 0.4 (milimita 10.0)". Mchoro wa ufungaji (hauko kamili hapa) utaonyesha vipimo vya moduli nzima, nafasi kati ya tarakimu na sehemu, na eneo la chini la usanidi wa pini 15. Uvumilivu wa vipimo vyote vya mstari kwa kawaida ni ±0.25 mm, isipokuwa ikitajwa vinginevyo. Muundo wa kimwili husaidia kufanikisha sifa ya "mtazamo mpana".

5.2 Mpangilio wa Pini na Mchoro wa Muunganisho

Onyesho hili linatumia usanidi wa cathode ya pamoja yenye multiplexing. Mchoro wa mzunguko wa ndani na jedwali la muunganisho wa pini umetolewa. Mambo muhimu ni kama ifuatavyo:

• Usanidi:Multiplexed common cathode. Cathode za LED za kila tarakimu (Digit1, Digit2, Digit3) zimeunganishwa pamoja ndani, na vile vile cathode za alama za desimali/kiashiria cha kushoto (L1, L2, L3). Anode za kila aina ya sehemu (A-G, DP) zinashirikiwa kati ya tarakimu zote.
• Kazi za Pini:Kiolesura cha pini 15 kinabainisha:
  • Common cathode pins for Digit 1 (Pin 1), Digit 2 (Pin 5), Digit 3 (Pin 7), and indicators L1/L2/L3 (Pin 14).
  • Anode pins for Segment A (Pin 12), B (Pin 11), C (Pin 3), D (Pin 4), E (Pin 2), F (Pin 15), G (Pin 8), and Decimal Point DP (Pin 6).
  • Segment C and indicator L3 share anode Pin 3. Segment A shares with L1 (Pin 12), and Segment B shares with L2 (Pin 11).
  • Several pins are marked as "No Connection" or "No Pin" (Pins 9, 10, 13).

This pinout requires a multiplexing drive circuit that sequentially activates the cathode of each digit while applying the correct anode pattern for the desired digit on that digit.

6. Soldering and Assembly Guide

The key assembly specification provided is the reflow soldering profile: the component can withstand a peak temperature of 260°C for 3 seconds, measured 1.6 mm (1/16 inch) below the package body. This is a standard lead-free soldering condition, consistent with the "Lead-Free Package" characteristic. Designers should follow IPC standard guidelines for PCB pad design, stencil aperture, and reflow profile ramp-up/cool-down rates to ensure reliable solder joints without subjecting the LED chip or internal bond wires to excessive thermal stress. Proper ESD (Electrostatic Discharge) handling procedures should be observed during all assembly stages.

7. Packaging and Ordering Information

Nambari ya sehemu ni LTC-4724JD. Kiambishi "JD" kinaweza kuashiria sifa maalum, kama rangi (Nyekundu ya Juu) na aina ya kifurushi. Kifaa kinaweza kutolewa kwenye mrija wa kinga ya umeme tuli au tray ili kulinda pini na kuzuia uharibifu wa ESD wakati wa usafirishaji na usindikaji. Uundaji wa ufungaji utakidhi vipimo vya anuwai ya joto la uhifadhi.

8. Application Notes and Design Considerations

8.1 Typical Application Circuit

多路复用共阴极设计旨在直接与微控制器单元（MCU）或专用显示驱动IC（例如MAX7219、TM1637）接口。典型电路涉及使用MCU的GPIO引脚用于段阳极（通常通过限流电阻），并使用GPIO引脚或晶体管开关（NPN或N沟道MOSFET）来吸收数字阴极的电流。软件中的多路复用例程必须快速刷新每个数字（通常>60Hz）以避免可见闪烁。

8.2 Key Design Calculations

• Kipingamlio cha Kikomo cha Mkondo (R_lim):For constant voltage drive (e.g., a 5V power supply), R_lim= (V_supply- V_F) / I_F. Using V_F=2.6V and the desired I_Fof 15mA: R_lim= (5 - 2.6) / 0.015 = 160 Ω. Standard 150 Ω or 180 Ω resistors are suitable. The resistor's power rating should be checked: P = I²* R.
• Multiplexing Duty Cycle and Peak Current:In 3-digit multiplexing, each digit is on for approximately 1/3 of the time. To achieve an average current I_avg, the peak current during its active period must be I_peak= I_avg* number of digits. If the desired average current per segment is 5mA, the peak current during the digit's active period should be approximately 15mA. This must remain below the 25mA continuous rating.
• Power Consumption:For a digit displaying "8" (all 7 segments lit), each segment I_F=10mA and V_F=2.6V, the power per segment is 26mW. The total power for this digit is 182mW. In multiplexed mode, this heat is dissipated sequentially across three digits, reducing the effective thermal load compared to static drive.

8.3 Design Considerations

• Viewing Angle:A wide viewing angle is beneficial for panels that may be viewed from off-axis positions.
• Contrast Ratio:Muundo wa paneli ya kijivu/na sehemu nyeupe hutoa tofauti kubwa ya rangi wakati LED nyekundu imezimwa, ikiboresha usomaji katika mwangaza mkali wa mazingira.
• Matumizi ya nguvu ya chini:Uwezo wa kufanya kazi kwa mkondo wa chini (mfano, 1mA inatosha kupata mwangaza unaoweza kupimika) hufanya iwe inafaa kwa vifaa vinavyotumia betri, hasa ikichanganywa na mfumo wa multiplexing ambao hupunguza matumizi ya wastani ya mkondo.
• Usimamizi wa joto:Hakikisha mpangilio wa PCB unaruhusu upitishaji fulani wa joto, hasa wakati sehemu zinazoendeshwa zikikaribia kikomo chao cha juu cha mkondo au zinapofanya kazi katika halijoto ya juu ya mazingira. Ni lazima kuzingatia mkunjo wa kupunguza mkondo wa mbele.

9. Technical Comparison and Differentiation

Ikilinganishwa na teknolojia za zamani (kama vile LED nyekundu ya kawaida ya GaAsP), teknolojia ya AlInGaP katika LTC-4724JD hutoa ufanisi mkubwa zaidi wa kutolea mwanga, na hivyo kutoa mwangaza mkubwa zaidi kwa mkondo sawa wa kuendesha, au matumizi ya nguvu ya chini kwa mwangaza sawa. Rangi ya "Super Red" (639nm) ni iliyojaa zaidi na inaonekana wazi zaidi kuliko LED nyekundu ya kawaida (takriban 620-625nm). Ikilinganishwa na maonyesho ya tarakimu moja, kitengo hiki cha tarakimu tatu kilichounganishwa huhifadhi nafasi nyingi kwenye PCB na hurahisisha usanikishaji kuliko kutumia vipengele vitatu tofauti. Kiolesura cha multiplexing, ingawa kinahitaji mzunguko wa kuendesha ulio changamani zaidi kuliko uendeshaji tuli, hupunguza kwa kiasi kikubwa idadi ya pini za udhibiti zinazohitajika na kontroller ndogo (mfano, uendeshaji tuli wa tarakimu 3 na nukta ya desimali unahitaji pini 11, wakati multiplexing inahitaji sehemu 8 + tarakimu 3 = pini 11, lakini kwa kawaida hurekebishwa zaidi kupitia kiendesha).

10. Frequently Asked Questions (Based on Technical Parameters)

Swali: Lengo la muundo wa "Cathode ya Pamoja" ni nini?
Jibu: Inaruhusu multiplexing. Kwa kushiriki anodi za sehemu kati ya tarakimu na kudhibiti cathode za tarakimu kwa pekee, unaweza kutumia seti moja ya madereva wa sehemu kuonyesha tarakimu tofauti kwenye kila tarakimu, na hivyo kupunguza kiwango cha pini za I/O zinazohitajika na kudhibiti.

Swali: Naweza kuendesha onyesho hili kwa mkondo wa moja kwa moja wa DC bila kufanya multiplexing?
Jibu: Kiufundi inawezekana, kwa kuunganisha cathode zote za pamoja pamoja na kuzichukulia kama onyesho la tarakimu 3 linalosimama. Hata hivyo, hii itahitaji madereva 7 (sehemu) + 1 (DP) + 3 (kiashiria) = 11 anode na kichujio cha cathode kinachoweza kushughulikia jumla ya mkondo wa sehemu zote zilizowashwa (mfano, hadi 7*25mA=175mA kwa kila tarakimu), ambayo haina ufanisi na hutumia pini zaidi.

Swali: Voltage ya mbele ya kawaida ni 2.6V. Naweza kuiendesha moja kwa moja kwa usambazaji wa nguvu wa microcontroller wa 3.3V?
Jibu: Ndio, lakini lazima iwe na resistor ya kudhibiti mkondo. Hesabu: R = (3.3V - 2.6V) / I_F. Kwa 10mA, R = 0.7V / 0.01A = 70 Ω. Hakikisha pini za GPIO za MCU zinaweza kutoa/kunyonya mkondo unaohitajika.

Swali: "Super red" inamaanisha nini ikilinganishwa na nyekundu ya kawaida?
Jibu: Super red kwa kawaida inarejelea LED yenye wavelength kuu kubwa kuliko takriban 630nm, ikitoa rangi nyekundu yenye kina zaidi na "safi" zaidi ikilinganishwa na ukiukaji wa rangi ya machungwa-nyekundu ya LED nyekundu ya kawaida (takriban 620-625nm). Hii inapatikana kwa vifaa vya kisasa vya semiconductor kama vile AlInGaP.

Swali: Je, udhibiti nje ya desimali/kiashiria (L1, L2, L3) vipi?
Jibu: Zinashiriki pini za anodi za sehemu A, B na C kwa mtiririko huo. Ili kuwasha kiashiria L1 kwa mfano, lazima uamilishe katoda ya pamoja ya kiashiria (pini 14) wakati huo huo ukiamilisha anodi ya sehemu A (pini 12), kama vile unavyotaka kuwasha sehemu A ya tarakimu.

11. Mfano wa Matumizi Halisi

Tukio: Kutengeneza usomaji rahisi wa voltamita wenye tarakimu 3.
Kikokotoo kidogo chenye Kigeuzi cha Analogi-hadi-Digitali (ADC) kinapima voltage (0-5V). Programu inabadilisha kipimo hicho kuwa thamani kati ya 0 na 5.00. Kisha inaigawa katika tarakimu tatu: mamia, makumi na mamoja/sehemu ya kumi (nukta ya desimali imewekwa baada ya tarakimu ya kwanza). Utaratibu wa kuzidisha unaoendeshwa katika usumbufu wa timer kila 5ms (kiwango cha kuwasha cha 200Hz).

1. Mzunguko 1:MCU inaweka muundo wa anodi wa sehemu kwa tarakimu ya "mamia" (k.m. "5") kwenye pini zake za pato. Kisha inawasha transistor inayochukua mkondo wa katoda ya tarakimu 1 (pini 1). Katoda za tarakimu zingine zote zimezimwa. Hii inaendelea kwa takriban 1.6ms.
2. Mzunguko 2:MCU inabadilisha muundo wa sehemu ya tarakimu ya "makumi" na kubadili uwezeshaji wa cathode kwa tarakimu 2 (pini 5).
3. Mzunguko 3:MCU huweka muundo wa sehemu kwa tarakimu ya "mamoja/sekunde ya kumi," ikijumuisha kuwezesha anode ya nukta ya decimal DP (pini 6). Inawezesha cathode ya tarakimu 3 (pini 7).

Mzunguko huu unarudiwa. Kutokana na ushawishi wa kuona, macho ya mwanadamu yanaona tarakimu zote tatu zikiwa zimewashwa kwa ustahimilivu kwa wakati mmoja. Upinzani wa kudhibiti mkondo huwekwa kwenye kila mstari wa anode ya sehemu. Mkondo wa wastani kwa kila sehemu ni mkondo wa kilele uliogawanywa na 3 (idadi ya tarakimu).

12. Kanuni ya Uendeshaji

Kanuni ya msingi ni mwanga unaotokana na umeme katika kiungo cha PN cha semiconductor. Wakati voltage ya upendeleo mzuri inayozidi voltage ya kuwasha diode inatumika kwenye chip ya LED ya AlInGaP, elektroni na mashimo huingizwa kwenye eneo lenye shughuli, ambapo huchanganyika. Mchanganyiko huu hutoa nishati kwa njia ya fotoni (mwanga). Urefu maalum wa wimbi wa 639nm huamuliwa na nishati ya pengo la bendi ya nyenzo ya semiconductor ya AlInGaP, ambayo imebuniwa wakati wa ukuaji wa epitaxial kwenye msingi wa GaAs. Kila sehemu ya onyesho ina chip moja au zaidi za hizi ndogo za LED. Mzunguko wa multiplexing unatumia ukweli kwamba macho ya mwanadamu hayawezi kugundua kuwasha na kuzima kwa haraka, na kuunda dhihaka ya onyesho la tarakimu nyingi zinazowaka kwa mfululizo, huku ikipunguza kwa kiasi kikubwa utata wa vifaa na matumizi ya nguvu.

13. Mwelekeo na Msingi wa Teknolojia

Onyesho la LED yenye sehemu saba linawakilisha teknolojia ya kusoma tarakimu iliyokomaa na yenye ufanisi wa gharama. Mwelekeo ndani ya uwanja huu ni kupitisha nyenzo zenye ufanisi zaidi (kama vile AlInGaP badala ya GaAsP ya zamani), voltage ya chini ya uendeshaji, na saizi ndogo za kufunga ili kufikia msongamano mkubwa zaidi. Pia kuna mwelekeo wa kuunganisha mizunguko ya kuendesha ndani ya moduli ya onyesho yenyewe (kwa mfano, kiolesura cha I2C au SPI), na hivyo kurahisisha mahitaji ya kontrolla ndogo ya nje. Ingawa maonyesho ya OLED na LCD yenye matrix ya nukta hutoa kubadilika zaidi kwa maudhui ya herufi na nambari na picha, LED zenye sehemu saba bado zina faida kubwa katika matumizi yanayohitaji mwangaza mkubwa sana, mtazamo mpana, uvumilivu wa joto kali, urahisi, na gharama nafuu (hasa kwa data ya nambari). Vipimo vya kufunga visivyo na risasi vinaonyesha mwelekeo wa tasnia ya kimataifa kuelekea kufuata kanuni za RoHS (Vizuizi vya Vitu Vyenye Madhara).