PT42-21B/TR8 Everlight Phototransistor (Other) In Stock
The Everlight PT42-21B/TR8 is a RoHS-compliant miniature surface-mount infrared phototransistor in a 2-pin SMD package with a 30 V collector-emitter breakdown voltage and 3 mA nominal light current. It offers low dark current of 100 nA for high-contrast optical sensing applications. Available from stock worldwide with competitive pricing.
- Manufacturer
- Everlight
- Package
- Other
- Pin Count
- 2
- Lifecycle
- ACTIVE
- Datasheet
- PT42-21B/TR8 Datasheet PDF
- Category
- Phototransistor
- Temp Range
- -25.0°C to 85.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
Key Features
- Infrared-sensitive phototransistor with 3 mA nominal light current and 100 nA maximum dark current for high-sensitivity optical detection
- 30 V collector-emitter breakdown voltage and 20 mA maximum on-state current support a wide range of signal switching applications
- Compact 2-pin SMD package with RoHS and Pb-free compliance enables automated PCB assembly in space-constrained sensor designs
Applications
The PT42-21B/TR8 is used in proximity sensors, optical encoders, and line-detection modules where a miniature SMD infrared phototransistor is required. Its low dark current of 100 nA and 3 mA light current enable reliable discrimination between ambient and IR-illuminated states in industrial counting and position feedback systems. Engineers also use this phototransistor in consumer electronics for touchless button sensing and paper-feed detection in printers and copiers.
Specifications
| Pbfree Code | Yes |
| YTEOL | 6.99 |
| Coll-Emtr Bkdn Voltage-Min | 30V |
| Configuration | SINGLE |
| Dark Current-Max | 100nA |
| Infrared Range | YES |
| Light Current-Nom | 3mA |
| Mounting Feature | SURFACE MOUNT |
| Number of Functions | 1 |
| On-State Current-Max | 0.02A |
| Optoelectronic Device Type | PHOTO TRANSISTOR |
| Peak Wavelength | 940nm |
| Power Dissipation-Max | 0.075W |
| Shape | ROUND |
| Size | 1.8mm |
| Surface Mount | YES |
| Package | Other |
Compliance & Regulatory
| RoHS Status | Compliant |
| Lead-Free | Yes (Pb-Free) |
| ECCN | EAR99 |
| HTS Code | 8541.40.70.80 |
Alternate & Equivalent Parts
No known alternates. Submit an RFQ and our team can suggest alternatives.
Frequently Asked Questions
What are the key electrical parameters of the Everlight PT42-21B/TR8 phototransistor?
The PT42-21B/TR8 has a 30 V minimum collector-emitter breakdown voltage, a nominal light current of 3 mA, and a maximum dark current of 100 nA. Maximum on-state current is 20 mA. These parameters make it a sensitive and reliable infrared detector for optical switches, proximity detectors, and encoder feedback systems operating at typical logic supply voltages.
How does the SMD package of PT42-21B/TR8 benefit automated optical sensor assembly?
The 2-pin SMD form factor of PT42-21B/TR8 is compatible with pick-and-place equipment and reflow soldering, enabling high-volume automated assembly at lower cost than through-hole alternatives. The miniature plastic body reduces PCB footprint to just a few square millimeters, allowing multiple phototransistors to be placed in proximity for array-based optical detection tasks such as barcode scanning and position encoding.
In proximity detection designs, how does the PT42-21B/TR8 compare to phototransistors with higher dark current?
With a maximum dark current of only 100 nA, the PT42-21B/TR8 provides a much larger signal-to-noise ratio between its 3 mA light current and dark state compared to phototransistors rated at 500 nA or higher. This 30:1 or greater contrast ratio makes it easier to set reliable detection thresholds in proximity and object-detection circuits, especially in industrial environments with high ambient IR noise at 30 V operating conditions.
Related Guides
ECMF02-4CMX8 Common-Mode Filter with ESD Protection: Selection Guide
Compare ECMF02-4CMX8 vs ECMF02-2AMX6, ECMF04-4HSM10, and other ST ECMF filters. Choose the right 4-channel common-mode filter with ESD protection for USB 2.0.
Jun 20, 2026
AD5204 Quad Digital Potentiometer Selection Guide (2026)
How to choose the right AD5204 quad digital potentiometer: compare 10kΩ vs 100kΩ variants, TSSOP vs SOIC packages, and SPI interface options for your design.
Jun 20, 2026
0402 10uF X5R Decoupling Design Guide for Compact Digital Rails
Application note for using CL05A106MP5NUNC-class 0402 10uF X5R MLCCs in compact digital rail decoupling designs.
Jun 19, 2026
How to Choose an 0805 10uF MLCC for Decoupling and Bulk Capacitance
Selection guide for choosing 0805 10uF MLCCs around CL21A106KOQNNNE, covering derating, dielectric, package, and sourcing checks.
Jun 19, 2026
Why Buy from FindMyChip
About Everlight
Everlight is a leading electronic component manufacturer. FindMyChip sources Everlight ICs directly from authorized China distributors, offering competitive pricing and reliable stock.
In Stock · 24h Response · Worldwide Shipping
Response within 24 hours · Worldwide shipping
“FindMyChip sourced our entire STM32 BOM in 48 hours when our usual distributor had 16-week lead times.”