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

Image Part Number Description / PDF Quantity Rfq
UNR911DG0L

UNR911DG0L

Panasonic

TRANS PREBIAS PNP 125MW SSMINI3

0

UNR422200A

UNR422200A

Panasonic

TRANS PREBIAS NPN 300MW NS-B1

0

UNR511NG0L

UNR511NG0L

Panasonic

TRANS PREBIAS PNP 150MW SMINI3

0

DRA2114E0L

DRA2114E0L

Panasonic

TRANS PREBIAS PNP 200MW MINI3

0

UNR212400L

UNR212400L

Panasonic

TRANS PREBIAS PNP 200MW MINI3

0

UNR9213G0L

UNR9213G0L

Panasonic

TRANS PREBIAS NPN 125MW SSMINI3

0

UNR511200L

UNR511200L

Panasonic

TRANS PREBIAS PNP 150MW SMINI3

0

UNR211100L

UNR211100L

Panasonic

TRANS PREBIAS PNP 200MW MINI3

0

UNR921BJ0L

UNR921BJ0L

Panasonic

TRANS PREBIAS NPN 125MW SSMINI3

0

UNRL21500A

UNRL21500A

Panasonic

TRANS PREBIAS NPN 150MW ML4-N1

0

UNR521N00L

UNR521N00L

Panasonic

TRANS PREBIAS NPN 150MW SMINI3

0

UNR91A3G0L

UNR91A3G0L

Panasonic

TRANS PREBIAS PNP 125MW SSMINI3

0

UNR92A9G0L

UNR92A9G0L

Panasonic

TRANS PREBIAS NPN 125MW SSMINI3

0

DRA9A24E0L

DRA9A24E0L

Panasonic

TRANS PREBIAS PNP 0.125W SSMINI3

0

UNR921TJ0L

UNR921TJ0L

Panasonic

TRANS PREBIAS NPN 125MW SSMINI3

0

UNR911TG0L

UNR911TG0L

Panasonic

TRANS PREBIAS PNP 125MW SSMINI3

0

UNR32ATG0L

UNR32ATG0L

Panasonic

TRANS PREBIAS NPN 100MW SSSMINI3

0

UNR212100L

UNR212100L

Panasonic

TRANS PREBIAS PNP 200MW MINI3

0

UNR31A6G0L

UNR31A6G0L

Panasonic

TRANS PREBIAS PNP 100MW SSSMINI3

0

UNR52ANG0L

UNR52ANG0L

Panasonic

TRANS PREBIAS NPN 150MW SMINI3

0

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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