Transistors - Bipolar (BJT) - Single, Pre-Biased

Image Part Number Description / PDF Quantity Rfq
MUN2211T3G

MUN2211T3G

Sanyo Semiconductor/ON Semiconductor

TRANS PREBIAS NPN 50V 100MA SC59

21804

FJY3005R

FJY3005R

SMALL SIGNAL BIPOLAR TRANSISTOR

18000

PDTC143TU,135

PDTC143TU,135

Nexperia

TRANS PREBIAS NPN 50V SOT323

0

NSBC144EF3T5G

NSBC144EF3T5G

SMALL SIGNAL BIPOLAR TRANSISTOR,

498233

MMDT5212W

MMDT5212W

Diotec Semiconductor

DIGITAL TR SOT-323 50V 100MA

0

PDTC123YMB,315

PDTC123YMB,315

NXP Semiconductors

PDTC123Y - NPN RESISTOR-EQUIPPED

0

DTD543XETL

DTD543XETL

ROHM Semiconductor

TRANS PREBIAS NPN 150MW EMT3

0

DRA5L14Y0L

DRA5L14Y0L

Panasonic

TRANS PREBIAS PNP 150MW SMINI3

6000

BCR198TE6327

BCR198TE6327

IR (Infineon Technologies)

BIPOLAR DIGITAL TRANSISTOR

27000

DRA3143X0L

DRA3143X0L

Panasonic

TRANS PREBIAS PNP 200MW SSSMINI3

9900

DTA115EUAT106

DTA115EUAT106

ROHM Semiconductor

TRANS PREBIAS PNP 200MW UMT3

2044

DDTA124ECA-7-F

DDTA124ECA-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PREBIAS PNP 200MW SOT23-3

489

DDTD122LC-7-F

DDTD122LC-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PREBIAS NPN 200MW SOT23-3

6000

DDTD122LU-7-F

DDTD122LU-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PREBIAS NPN 200MW SOT323

1009412000

DDTD114TU-7-F

DDTD114TU-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PREBIAS NPN 200MW SOT323

0

NSB9435T1G

NSB9435T1G

SMALL SIGNAL BIPOLAR TRANSISTOR,

750

DRA3114T0L

DRA3114T0L

Panasonic

TRANS PREBIAS PNP 100MW SSSMINI3

19990

DDTA123YE-7-F

DDTA123YE-7-F

Zetex Semiconductors (Diodes Inc.)

TRANS PREBIAS PNP 150MW SOT523

0

DTC143XU3HZGT106

DTC143XU3HZGT106

ROHM Semiconductor

DTC143XU3HZG IS AN DIGITAL TRANS

2595

PDTA124TMB,315

PDTA124TMB,315

Nexperia

NOW NEXPERIA PDTA124TMB - SMALL

168027

Transistors - Bipolar (BJT) - Single, Pre-Biased

1. Overview

Pre-biased bipolar junction transistors (BJTs) are discrete semiconductor devices with integrated biasing resistors, designed to simplify circuit design and improve operational stability. Unlike standard BJTs requiring external biasing components, pre-biased BJTs incorporate internal resistors to set the base-emitter voltage and collector current. These devices are critical in modern electronics for applications demanding compact design, consistent performance, and reduced component count. Their ability to maintain stable operation under varying temperature and voltage conditions makes them essential in consumer electronics, industrial automation, and automotive systems.

2. Main Types and Functional Classification

TypeFunctional FeaturesApplication Examples
NPN Pre-Biased BJTPositive bias resistor network, low-side switchingLogic-level switching, LED drivers
PNP Pre-Biased BJTNegative bias resistor network, high-side switchingPower supply control, relay drivers
Digital TransistorIntegrated resistors with ESD protectionDigital logic circuits, portable devices

3. Structure and Composition

Pre-biased BJTs consist of a silicon semiconductor die with three doped regions (emitter, base, collector) forming two p-n junctions. The key structural elements include: - Monolithic Resistor Network: Thin-film or diffused resistors embedded in the die for fixed biasing - Metal Contacts: Aluminum or copper layers for external connections - Encapsulation: Plastic or ceramic packaging with standard pinouts (e.g., SOT-23, TO-92) - Passivation Layer: Silicon dioxide/nitride coating to prevent surface contamination

4. Key Technical Specifications

ParameterDescriptionImportance
Current Gain (hFE)Ratio of collector to base currentDetermines amplification capability
Max Collector Voltage (VCEO)Max voltage across collector-emitterDefines operating voltage range
Transition Frequency (fT)Frequency response limitCritical for RF and switching applications
Power Dissipation (Ptot)Max thermal power handlingDictates thermal management needs
Built-in Resistor Ratio (R1/R2)Internal resistor division ratioControls bias point stability

5. Application Areas

Main industries and typical equipment: - Consumer Electronics: Mobile phone chargers, wearable devices - Industrial Automation: PLC modules, motor drivers - Automotive: Sensor interfaces, LED lighting systems - Telecommunications: Base station power amplifiers - Power Management: DC-DC converter switches

6. Leading Manufacturers and Products

ManufacturerKey ProductsFeatures
ON SemiconductorMMBT3904L200mA NPN transistor with 47k bias resistors
Toshiba2SB1958PNP device with built-in 10k /4.7k resistor network
STMicroelectronicsSM6T120NAutomotive-grade digital transistor with ESD protection

7. Selection Guidelines

Key considerations: - Match hFE with required amplification/saturation characteristics - Confirm VCEO rating exceeds circuit voltage requirements - Select resistor ratios for desired bias point (e.g., R1=10k , R2=22k for mid-range bias) - Prioritize thermal performance in high-power applications - Consider package type (SMD vs. through-hole) for PCB constraints

8. Industry Trends

Emerging trends include: - Miniaturization: Development of 0.4mm pitch WLCSP packages - Integrated protection: ESD/clamp diodes in standard designs - High-frequency variants: fT > 5GHz for 5G infrastructure - Automotive qualification: Increased demand for AEC-Q101 certified devices - Green manufacturing: Lead-free packaging and low-toxicity materials

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