LTR-301 Phototransistor Datasheet - Side-View Package - Clear Lens - 30V Collector-Emitter Voltage - Simplified Chinese Technical Documentation

1. Product Overview

LTR-301 silicon NPN phototransistor ne, wanda aka tsara don aikace-aikacen gano infrared. Yana amfani da kayan rufi na filastik mai kallon gefe tare da ruwan tabarau mai gani, wanda aka inganta don hanzarin hasken infrared (yawanci tsawon zango 940nm). Na'urar tana nufin canza hasken infrared mai shiga zuwa madaidaicin igiyar ruwa akan mashaya mai tattarawa.

Babban aikin na'urar shine a matsayin mai canza haske-zuwa-igiyar ruwa. Lokacin da hasken infrared ya haskaka yankin tushe mai hankali ga haske, yana haifar da nau'i-nau'i na lantarki da rami. Wannan igiyar ruwa ta haifar da haske tana aiki azaman igiyar ruwa ta tushe, wanda daga baya aka ƙara girma ta hanyar ribar igiyar ruwa (β) na transistor, yana haifar da igiyar ruwa mai tattarawa mafi girma sosai. Wannan siginar da aka ƙara girma yana da sauƙin haɗawa tare da da'irorin lantarki na gaba, kamar microcontroller ko amplifier.

Babban fa'idodinsa sun haɗa da faɗin kewayon aikin igiyar ruwa mai tattarawa, wanda ke ba da sassauci na ƙira don biyan buƙatun hankali daban-daban. Ruwan tabarau da aka haɗa yana ƙara hankalinsa ta hanyar mayar da hankali ga hasken mai shiga zuwa yanki mai tasiri. Tsarin kayan rufi mai kallon gefe ya dace musamman don aikace-aikacen da tushen haske yake layi daya da saman PCB, kamar mai katse rami ko firikwensin nunawa. Rufin da ke gani yana ba da damar amsawar bakan haske mai faɗi, ko da yake an inganta shi don hasken infrared.

Kasuwar da aka yi niyya don wannan kayan ta haɗa da na'urorin lantarki na masu amfani, sarrafa masana'antu, tsarin tsaro, da aikace-aikacen firikwensin daban-daban. Amfanin yau da kullun ya haɗa da gano abu, firikwensin matsayi, mai ƙididdiga juyawa, gano takarda na firinta da kuma sauyawa ba tare da taɓawa ba.

2. Bincike Cikakken na Sigogi na Fasaha

2.1 Matsakaicin Matsakaici na Gabaɗaya

These ratings define the stress limits that may cause permanent damage to the device. Operation under these conditions is not guaranteed.

• Power Dissipation (P_D):100 mW. This is the maximum total power the device can dissipate as heat. Exceeding this limit risks thermal runaway and failure.
• Collector-Emitter Voltage (V_CEO):30 V. The maximum voltage that can be applied between the collector and emitter pins when the base is open (no illumination).
• Emitter-Collector Voltage (V_ECO):5 V. The maximum reverse voltage allowed between the emitter and collector.
• Operating temperature (T_A):-40°C to +85°C. The ambient temperature range that ensures reliable operation.
• Storage temperature (T_stg):-55°C to +100°C.
• Pin soldering temperature:260°C for 5 seconds at a distance of 1.6mm from the package body. This is crucial for wave soldering or manual soldering processes.

2.2 Halayen Lantarki da Na'urar Gani

These parameters are specified at an ambient temperature (T_A) of 25°C, defining the device's performance under specific test conditions.

• Collector-Emitter Breakdown Voltage, V_(BR)CEO:30 V (min). Tested at I_C= 1mA and no illumination (E_e= 0 mW/cm²). This confirms the absolute maximum ratings.
• Emitter-Collector Breakdown Voltage, V_(BR)ECO:5 V (minimum). Tested at I_E= 100µA with no illumination.
• Collector-emitter saturation voltage, V_CE(SAT):0.4 V (maximum). This is the voltage drop across the transistor when it is fully "on" (saturated) under an irradiance of 1 mW/cm² and I_C= 0.1mA. For switching applications, a lower V_CE(SAT)helps minimize power loss.
• Rise time (T_r) and fall time (T_f):) are 10 µs (typical) and 15 µs (typical), respectively. These parameters define the switching speed. At V_CC=5V, I_C=1mA, R_L=1kΩ condition measurement. This asymmetry is common in phototransistors due to charge storage effects.
• Collector dark current (I_CEO):100 nA (maximum). This is the device's leakage current flowing from collector to emitter under complete darkness (E_e= 0 mW/cm²) and V_CE= 10V. Low dark current is crucial for achieving a good signal-to-noise ratio, especially in low-light sensing.

3. Bayanin Tsarin Rarrabawa

LTR-301 employs a binning system for its key parameter—the on-state collector current (I_C(ON)). Binning is a quality control process that categorizes components into specific ranges or "bins" based on measured performance. This ensures consistency for the end user.

The parameter for binning is I_C(ON), measured under standardized conditions: V_CE= 5V, E_e= 1 mW/cm², λ = 940nm. Based on the measured current output, the device is placed into one of eight bins (A through H).

• Bin A:0.20 - 0.60 mA
• Gear B:0.40 - 1.08 mA
• Gear C:0.72 - 1.56 mA
• Gear D:1.04 - 1.80 mA
• Gear E:1.20 - 2.40 mA
• Gear F:1.60 - 3.00 mA
• Gear G:2.00 - 3.84 mA
• Gear H:2.56 mA (Minimum)

Design Impact:When designing a circuit, the grade used must be considered. For example, a device with grade H guarantees a higher minimum sensitivity than one with grade A. This is crucial for setting comparator thresholds or analog gain stages. If your design requires a minimum signal level, you must specify the grade code that meets that requirement.

4. Bincike kan Lankwilar Aiki

The datasheet provides several characteristic curves illustrating how parameters vary with operating conditions.

4.1 Collector dark current vs. Ambient temperature (Figure 1)

The graph shows I_CEOincreases exponentially with temperature. At 85°C, the dark current can be several orders of magnitude higher than at 25°C. This is a fundamental characteristic of semiconductors (leakage current approximately doubles every 10°C).Design Considerations:A cikin yanayin zafi mai girma, ƙarar daɗaɗɗen igiyoyin duhu na iya zama kuskuren ake ɗauka a matsayin sigina na haske na gaskiya. Kewayon na iya buƙatar ramuwa na zafin jiki ko kuma ƙofar gano mafi girma.

4.2 Collector power derating vs. Ambient temperature (Figure 2)

Wannan lanƙwasa yana nuna matsakaicin izinin amfani da wutar lantarki (P_C) yana raguwa a layi tare da hawan zafin muhalli (T_A) sama da 25°C. A 85°C, matsakaicin amfani da wutar lantarki ya ragu sosai.Design Considerations:Tabbatar cewa aikin wutar lantarki (V_CE* I_C) ya kasance ƙasa da layin raguwa a cikin mafi girman T_Ada ake tsammani, don hana yin amfani da wutar lantarki mai yawa.

4.3 Rise/Fall time vs. Load resistance (Figure 3)

The diagram illustrates the trade-off between switching speed and signal amplitude. As the load resistance (R_L) increases, the rise and fall times also increase. A larger R_Lcan provide a larger output voltage swing (ΔV = I_C* R_L), but it slows down the response speed.Design Considerations:For high-speed applications (e.g., data communication), a smaller R_Lis used. To maximize voltage output in slower applications (e.g., ambient light sensing), a larger R_L。

4.4 Relative Collector Current vs. Irradiance (Figure 4)

This is a transfer characteristic curve, indicating that when V_Cis fixed (5V), within a certain range, the collector current (I_e) is proportional to the incident optical power (irradiance, E_CE) Yana kusan layi ne. Wannan layin yana da mahimmanci ga aikace-aikacen ma'aunin haske na analog.

4.5 Sensitivity Pattern (Figure 5)

Wannan zanen polar yana kwatanta hankalin kusurwar na'urar. Phototransistor yana da mafi girman hankali ga hasken da ke shiga a kai tsaye zuwa ruwan tabarau (0°). Hankali yana raguwa yayin da kusurwar shigarwa ta ƙaru, yawanci yana raguwa zuwa 50% (rabin kusurwa) a wani takamaiman kusurwa (kamar yadda aka ba da shawarar a cikin hoton ±10° zuwa ±20°).Design Considerations:Wannan yana ayyana filin gani. Daidaitawar injiniya tsakanin mai fitarwa da mai ganowa yana da mahimmanci. Hakanan ana iya amfani da shi don hana hasken da ba a so daga wuraren da ba a so.

5. Mechanical and Packaging Information

Ana amfani da wannan na'urar tare da kunshewar filastik mai gani ta gefe. Kalmar "side-look" tana nuna cewa yankin mai hankali ga haske yana gefen kunshewar, a layi daya da fil, ba a saman ba. Wannan yana dacewa sosai don fahimta a cikin jirgin PCB.

Bayanin Mahimman Girmansa:

• All dimensions are in millimeters, with a general tolerance of ±0.25mm unless otherwise specified.
• Pin pitch is measured at the point where the pins exit the package body, which is critical for PCB footprint design.
• The package incorporates a lens molded into the plastic to enhance optical collection efficiency.

Polarity Identification:The longer pin is typically the collector. However, always refer to the package outline in the full datasheet for final identification, usually indicated by a flat on the package or a mark on the lens.

6. Soldering and Assembly Guide

The key parameter provided is the pin soldering temperature: a maximum of 260°C for 5 seconds, measured 1.6mm (0.063 inches) from the package body. This is the standard rating for through-hole components.

Process Recommendation:

• Wave Soldering:Ensure the temperature profile does not exceed the specified limits at the pin/package junction. Preheating is critical to minimize thermal shock.
• Hand Soldering:Use a temperature-controlled soldering iron. Heat the pin/pad connection quickly and effectively, avoiding prolonged contact with the component body.
• Cleaning:Yi amfani da wanki mai jituwa da kayan rufi na filastik. Guji amfani da tsaftacewa ta ultrasonic sai dai idan an tabbatar da amincin sa ga na'urar.
• Ajiya:Ajiya a cikin yanayi mai bushewa, mai hana tashin wutar lantarki a cikin kewayon zafin jiki da aka kayyade (-55°C zuwa +100°C) don hana ɗaukar danshi (wanda zai iya haifar da "fashewar gasa" a lokacin sake zafi) da lalacewa ta hanyar fitar da wutar lantarki.

7. Bayanin Aikace-aikace da La'akari da Ƙira

7.1 Da'irar Aikace-aikace ta Al'ada

1. Sauya lambobi (Gano abu):Fototransistor yana haɗuwa da resistor na ja sama (R_L) a jere zuwa V_CC. The collector node is connected to a digital input (e.g., microcontroller GPIO or Schmitt trigger). In darkness, I_Cis very low (I_CEO), so the output is pulled up to a high level V_CC. When illuminated, I_Cincreases, pulling the output voltage low to near V_CE(SAT). The value of R_Lis chosen based on the required switching speed (see Figure 3) and the desired logic low voltage level: R_L≈ (V_CC- V_CE(SAT)) / I_C(ON).

2. Analog Light Intensity Meter:The phototransistor is connected in a similar configuration, but the collector voltage is fed to an analog-to-digital converter (ADC) input. Due to the roughly linear relationship shown in Figure 4, the ADC reading can be correlated with light intensity. A higher R_Lprovides a larger voltage swing for better ADC resolution but reduces bandwidth.

7.2 Muhimman Abubuwan Ƙira

• Light Source Matching:For optimal performance, pair the phototransistor with an infrared LED emitter that has the same peak wavelength (940nm).
• Electrical Load:The phototransistor is a current source. The load resistor converts this current into a voltage. Select R_LTo balance signal level, speed, and power consumption.
• Ambient Light Rejection:This device responds to all light, not just infrared. Use an optical filter (black IR-transmissive plastic) or a modulated (pulsed) light source with synchronous detection to suppress ambient 50/60Hz light noise and DC ambient light.
• Bias:Ensure the operating V_CEis within the recommended range (well below 30V), and the power dissipation (V_CE* I_C) is within limits, especially at high temperatures.

8. Kwatancen Fasaha da Bambance-bambance

Compared to photodiodes, phototransistors provide internal gain, producing a larger output signal for the same light input, which simplifies subsequent amplifier design. However, this comes at the cost of slower response time (microseconds for phototransistors vs. nanoseconds for photodiodes) and a higher temperature sensitivity of the dark current.

The specific differentiation of the LTR-301 lies in itsside-view package.(less common than top-view types) and itsclear lens.(as opposed to tinted or black). The clear lens provides a broader spectral response, which can be an advantage or a disadvantage depending on the need to suppress visible light. The detailed binning system allows for precise selection of sensitivity, a key advantage for high-volume production requiring consistent performance.

9. Frequently Asked Questions (FAQ)

Q: What is the difference between the different bins? Which one should I choose?
Amsa: Matakan saiti ana rarrabe su bisa ga hankalin na'urar (I_C(ON)). Zaɓi matakin saiti bisa ga mafi ƙarancin igiyar wutar lantarki da ake buƙata a cikin kewayon. Don mafi girman hankali/tsawon nisa, zaɓi mafi girman matakin saiti (misali H). Don aikace-aikacen da ke da hankali ga farashi kuma ana iya karɓar ƙarancin hankali, ƙananan matakin saiti (misali A) na iya isa.

Tambaya: Me yasa siginar fitarwa tana da amo ko rashin kwanciyar hankali?
Amsa: Wannan yawanci yana faruwa ne saboda hasken muhalli (hasken rana, fitilun fluorescent) ko amo na lantarki. Maganganun sun haɗa da: 1) Amfani da tushen hasken infrared da aka daidaita kuma a tace siginar karɓa. 2) Haɗa capacitor (10nF - 100nF) a cikin layi tare da resistor nauyi R_Ldon tace amo mai girma (wannan zai rage saurin amsawa). 3) Tabbatar da garkuwa da ƙasa da suka dace.

Tambaya: Zan iya amfani da shi tare da tushen haske mai gani?
Amsa: A'a, kunshe mai bayyana yana nufin zai kuma amsa ga hasken gani da kuma hasken infrared. Duk da haka, hankalinsa yawanci ana siffanta shi kuma ana inganta shi don hasken infrared na 940nm. Amsa ga hasken gani zai bambanta, kuma takaddun bayanai ba su ba da garanti ba.

Tambaya: Yaya ake lissafin amsawa ko hankali?
A: Responsivity is not directly given. You can estimate it from the I_C(ON)specifications. For example, for grade E (minimum 1.20mA at 1 mW/cm²), the minimum responsivity is approximately 1.20 mA / (1 mW/cm²) = 1.20 mA/(mW/cm²). Please note, this is a rough estimate as the effective area is not specified.

10. Practical Use Case Examples

Scenario: Paper detection in a printer.Build a reflective sensor using an LTR-301 and an infrared LED. Place them side-by-side, facing the paper path. The IR LED is continuously on. When no paper is present, light reflects weakly from a distant surface, resulting in low phototransistor output. When paper passes directly under the sensor, it reflects a strong signal back to the phototransistor, causing I_Cto increase sharply, and the collector node voltage drops accordingly.

Design Steps:
1. Select a grade (e.g., grade D or E) that provides sufficient signal current from the expected paper reflection.
2. Select R_LFor a 5V power supply, the target logic low voltage is 0.8V, and using the I of gear D_C(ON,min)(1.04mA): R_L≤ (5V - 0.8V) / 1.04mA ≈ 4.0kΩ. A standard 3.3kΩ resistor will be suitable, providing good signal margin.
3. Connect the collector node to a comparator or microcontroller interrupt pin. Set a threshold voltage (e.g., 2.5V) at the inverting input of the comparator to reliably detect the presence/absence of paper.
4. Mechanically align the sensor so that the beam of the infrared LED and the field of view of the phototransistor intersect on the paper surface.

11. How It Works

A phototransistor is essentially a Bipolar Junction Transistor (BJT) whose base current is generated by light, not by an electrical connection. In an NPN phototransistor like the LTR-301:

1. Infrared photons with sufficient energy (for silicon, wavelength ≤1100nm) penetrate the transparent package and are absorbed by the semiconductor material (mainly in the base-collector depletion region).
2. This absorption generates electron-hole pairs.
3. The electric field in the reverse-biased base-collector junction separates these carriers: electrons to the collector, holes to the base.
4. The accumulation of holes in the base region lowers the base-emitter barrier, effectively acting as a positive base current (I_B).
5. This photogenerated base current is then amplified by the transistor's current gain (β or h_FE), producing a collector current: I_C= β * I_B(photo). This is the source of the device gain.

The side-view package positions this photosensitive junction on the side and incorporates a lens to focus the incident light for improved efficiency.

12. Technology Trends

Phototransistors like the LTR-301 represent a mature, cost-effective technology. Current trends in photosensing include:

• Integration:A shift towards integrated solutions that combine the photodetector, amplifier, digitizer, and logic (e.g., I²C output light sensors) on a single chip, reducing the number of external components and simplifying design.
• Miniaturization:Developing smaller surface-mount device (SMD) package phototransistors for space-constrained applications.
• Specialization:Devices with built-in spectral filters (e.g., for RGB sensing or specific IR bands) or daylight-blocking filters are becoming increasingly common for robust operation in various environments.
• High-Speed:Although phototransistors are generally slower than photodiodes, ongoing development aims to increase their bandwidth for data communication applications (e.g., infrared remote controls, simple optical data links).

Despite these trends, discrete phototransistors remain highly relevant due to their simplicity, low cost, high sensitivity, and the design flexibility offered by configuring gain and bandwidth with external components.