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
- Price
- From $0.0370(MOQ 1000)
- Temp Range
- -25.0°C to 85.0°C
- RoHS
- Compliant
- Lead Time
- 3–7 business days
- Shipping
- DHL Express · Worldwide
What are the key features of PT42-21B/TR8?
- 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
What is PT42-21B/TR8 used for?
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.
What are the specifications of PT42-21B/TR8?
| 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 |
Where can I find the PT42-21B/TR8 datasheet?
PT42-21B/TR8 Datasheet DownloadOfficial datasheet from Everlight
What are equivalent replacements for PT42-21B/TR8?
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
DP83TG720SWRHATQ1 Automotive Ethernet PHY Selection Guide
Choose DP83TG720SWRHATQ1 by comparing MAC interfaces, exact ordering codes, qualification evidence, and documented supply offers.
Nov 15, 2026
TLV76033 Selection Guide: Headroom, Heat, and Sourcing
Choose a TLV76033 3.3-V supply using manufacturer ratings, load profiles, dropout calculations, thermal checks, and exact orderable parts.
Nov 14, 2026
DP83TG720SWRHATQ1 Automotive Ethernet Board Design Guide
A practical DP83TG720SWRHATQ1 board checklist for host interfaces, startup, channel validation, qualified variants, and sourcing.
Nov 14, 2026
BQ76942PFBR Battery Monitor Selection and Procurement Guide
Choose BQ76942PFBR by cell count, protection architecture, factory configuration, measurement needs, and a controlled sourcing specification.
Nov 13, 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.
| Qty. | Unit Price | Ext. Price |
|---|---|---|
| 1000+ | $0.0500 | $50.00 |
| 3000+ | $0.0450 | $135.00 |
| 27000+ | $0.0370 | $999.00 |
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.”
You May Also Like
SFH628A-2
Vishay
Phototransistor
TCZT8020-PAER
Vishay
Phototransistor
OPI1264B
OPTEK TECHNOLOGY
Phototransistor
TLP183(GB-TPL,E
Toshiba
Phototransistor
APDS-9006-020
Avago Technologies
Phototransistor
TIL191
Isocom
Phototransistor
PT480FE0000F
Sharp Microelectronics
Phototransistor
ISQ203
Isocom
Phototransistor
HCPL-0723-000E
Avago Technologies
Phototransistor
ACPL-824-300E
Avago Technologies
Phototransistor
PC357NJ0000F
Sharp Microelectronics
Phototransistor
GP1S094HCZ0F
Sharp Microelectronics
Phototransistor
OPB625
OPTEK TECHNOLOGY
Phototransistor
SFH 9500
OSRAM
Phototransistor
SFH 3605
OSRAM
Phototransistor
SFH 309 FA-4/5
OSRAM
Phototransistor
BPY 62
OSRAM
Phototransistor
ISP817XC
Isocom
Phototransistor
TLPN137(F)
Toshiba
Phototransistor
TLP3546(F)
Toshiba
Phototransistor
TLP2962
Toshiba
Phototransistor
TLP293(BL
Toshiba
Phototransistor
TLP291(Y,SE(T
Toshiba
Phototransistor
TLP290(SE(T
Toshiba
Phototransistor