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2N449 PDF Datasheet – Transistor, NPN, 15V, -20mA, TO-39

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Part Number: 2N449

Function: 15V, -20mA, NPN Transistor.

Package: 3-Pin TO-39 Type

Manufacturer: New Jersey Semiconductor

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2N449 datasheet pdf

Description

The 2N449 is a low-power bipolar junction transistor rated for 15V operation and a maximum collector current of -20mA, typically used in small-signal applications. It offers modest power dissipation and is suitable for low-level amplification and switching tasks in compact electronic designs. This transistor is commonly applied in signal processing, low-current switching, and general-purpose analog circuits.

Features

  • Low power dissipation of 65mW
  • Suitable for small-signal amplification
  • Compact and efficient for low-current circuits
  • Stable operation within limited temperature range

Absolute Maximum Ratings (Tc = 25 °C)

Parameter Symbol Value Unit
Collector-Base Voltage VCBO 15 V
Emitter-Base Voltage VEBO 15 V
Collector Current IC -20 mA
Collector Power Dissipation PC 0.065 W
Junction Temperature Tj 85 °C
Storage Temperature Tstg -55 to 85 °C

Design Notes

  • Ensure collector current remains within 20mA to avoid device damage
  • Suitable for low-power circuits with minimal heat generation
  • Biasing must be carefully designed for stable small-signal amplification
  • Limited thermal range requires controlled operating environment
  • Not suitable for high-frequency or high-power applications

Typical Circuit Usage

  • Low-level signal amplification
  • Small current switching circuits
  • Sensor interface stages
  • Pre-amplifier circuits
  • Basic transistor switching applications

How to Choose This Part

  • Select for low-voltage, low-current applications
  • Ideal for compact and low-power analog designs
  • Ensure thermal limits are not exceeded in operation
  • Use where high gain or power handling is not critical
  • Consider alternatives for wider temperature or higher current needs

Applications

  • Signal processing circuits
  • Low-power electronic devices
  • Instrumentation circuits
  • Educational and prototyping designs
  • Embedded analog interfaces

Alternative / Equivalent Products

  • 2N3904 (general-purpose NPN transistor)
  • BC547 (low-noise small-signal transistor)
  • 2N2222 (higher current alternative)
  • PN2222A (plastic package variant)
  • BC548 (similar small-signal transistor)

2N449 Datasheet

2N449 pdf

SFR16S0 Datasheet – Axial Metal Film Resistor ( PDF )

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Part Number: SFR16S0

Function: Standard Metal Film Leaded Resistor

Package: Axial Type

Manufacturer: Vishay Semiconductors

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SFR16S0 datasheet

Description

SFR16S0 is an axial leaded metal film resistor constructed using a homogeneous metal alloy film deposited on a high-grade ceramic substrate. The resistive value is precisely adjusted via a helical trimming process, and the component is encapsulated with a protective lacquer coating, ensuring excellent stability, low noise, and high reliability in various electronic applications.

Features

  • Metal film technology for high precision and stability
  • Compact size: 0204 package (SFR16S series)
  • Low noise performance (≤ 1.5 µV/V for R > 1 MΩ)
  • Excellent temperature stability
  • High reliability due to protective lacquer coating (light-blue)
  • Resistant to cleaning solvents (IEC 60068-2-45 compliant)
  • Compatible with both Pb-free and leaded soldering processes

Construction Details

  • Resistive element: deposited metal alloy film
  • Substrate: high-grade ceramic body
  • Trimming: helical groove for precise resistance adjustment
  • Leads: tinned electrolytic copper, welded to end caps
  • Coating: insulating lacquer for environmental protection

Electrical Characteristics (Typical)

  • Resistance range: typically from a few ohms up to several megaohms
  • Tolerance: commonly ±1%, ±2%, ±5% (depending on variant)
  • Temperature coefficient (TCR): typically ±50 ~ ±100 ppm/°C
  • Rated power: ~0.25W (at 70°C ambient, for SFR16S)
  • Low voltage coefficient and excellent long-term stability

Functional Description

  • Provides precise resistance for current limiting, voltage division, and signal conditioning
  • Low noise makes it suitable for analog and precision circuits
  • Metal film structure ensures minimal drift over time and temperature

Design Notes

  • Prefer metal film over carbon film for precision and low-noise applications
  • Ensure power derating above 70°C ambient
  • Maintain adequate spacing for high-voltage applications
  • Avoid excessive mechanical stress during PCB assembly
  • Consider TCR impact in precision analog circuits

Typical Applications

  • Precision analog circuits
  • Voltage dividers and reference networks
  • Signal conditioning and filtering
  • Audio circuits (low noise requirement)
  • Industrial and consumer electronics

How to Choose This Resistor

  • Select tolerance based on required accuracy (e.g., ±1% for precision)
  • Check power rating vs. actual dissipation with margin
  • Consider TCR for temperature-sensitive designs
  • Choose metal film for stability vs. carbon film for cost-sensitive designs

Alternative / Equivalent Products

  • Yageo MFR series (metal film resistor)
  • Vishay MRS25 series (higher power alternative)
  • KOA Speer MF1/4 series
  • Carbon film resistors (lower cost, higher noise alternative)

Other data sheets are available within the file:

SFR16S0004872FR500, SFR2500, SFR25H0

SFR16S0 Datasheet PDF Download


SFR16S0 pdf