onsemi PN4249_D75Z

Overview

PN4249_D75Z from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor (BJT) designed for amplification and switching applications with continuous collector current up to 500 mA and V_CEO = 60 V. It operates across –55°C to +150°C, features h_FE of 100–300 at I_C = 100 µA, and is housed in a TO-92 package with collector-first lead orientation per D75Z tape-and-reel configuration.

For engineers reviewing the PN4249_D75Z datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, 625 mW power dissipation at 25°C, low V_CE(sat) of 0.25 V at I_C = 10 mA/I_B = 0.5 mA, thermal resistance R_θJA = 200°C/W, and suitability for discrete analog gain stages and low-speed digital switching.

Technical Context

The PN4249_D75Z implements a silicon planar epitaxial PNP BJT structure optimized for general-purpose linear amplification and saturated switching. Its DC current gain (h_FE) is specified over a wide range (100–300), supporting consistent biasing across production lots. The device exhibits low output capacitance (C_ob = 6.0 pF) and moderate noise figure (3.0 dB at 1 kHz), enabling stable operation in audio preamp and signal conditioning circuits.

Thermal design is constrained by R_θJA = 200°C/W and R_θJC = 83.3°C/W, requiring careful PCB copper area allocation for power handling above 100 mW. Absolute maximum ratings are defined with T_J ≤ 150°C, and derating begins at 5.0 mW/°C above 25°C ambient - critical for reliability in enclosed industrial enclosures.

Key Specifications

Pinout & Package

PN4249_D75Z is supplied in a TO-92 plastic package with straight leads and collector-first orientation per EOL code D75Z (Order Style P). The flat side of the transistor faces upward when mounted, and the first wire off the reel is the collector terminal.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP general-purpose amplifier applications.

Compared with MPSA92 and BC807-40, PN4249_D75Z offers balanced V_CEO/h_FE/package trade-offs for through-hole prototyping and medium-voltage industrial controls - retaining TO-92 accessibility while delivering predictable gain and low saturation loss without HV overhead or SMT dependency.

Availability

PN4249_D75Z is available at Aetrix Electronics and suitable for audio pre-amplification, DC load switching, and level translation applications requiring stable component supply, long-term manufacturability, and legacy through-hole compatibility.

Supply support for PN4249_D75Z includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Fairchild Semiconductor was a U.S.-based semiconductor company specializing in power management, analog, and discrete components before its acquisition by ON Semiconductor in 2016.

The PN4249_D75Z belongs to Fairchild's legacy general-purpose BJT family, engineered for cost-sensitive, high-reliability linear and switching functions in industrial, consumer, and computing equipment.

FAQ

What is the pin configuration of PN4249_D75Z?

PN4249_D75Z uses a TO-92 package with collector-first orientation (EOL code D75Z, Order Style P). When viewing the flat side of the transistor facing up, the left-to-right pin order is Collector–Base–Emitter. This matches standard TO-92 mechanical layout but differs from emitter-first variants like D74Z.

Does PN4249_D75Z support pulsed operation beyond its continuous ratings?

Yes - PN4249_D75Z supports pulsed operation with pulse width ≤300 µs and duty cycle ≤2.0%, as validated in its datasheet test conditions. For such use, peak collector current may exceed 500 mA provided average power remains within derated P_D limits and junction temperature stays ≤150°C.

What is the typical noise performance of PN4249_D75Z in audio applications?

PN4249_D75Z delivers a noise figure of 3.0 dB at V_CE = 5 V, I_C = 250 µA, R_S = 1 kΩ, f = 1 kHz, and BW = 150 Hz. This makes it suitable for low-noise pre-amplifier stages where signal integrity is critical and external filtering is minimized.

Can PN4249_D75Z be used as a direct replacement for PN2222A in circuit designs?

No - PN4249_D75Z is a PNP transistor, whereas PN2222A is NPN. They are complementary but not interchangeable without reversing biasing and signal polarity. Substituting PN4249_D75Z for PN2222A would invert logic states and likely prevent circuit operation unless the schematic is redesigned.

What thermal derating applies to PN4249_D75Z above 25°C ambient?

PN4249_D75Z must be derated at 5.0 mW/°C above 25°C ambient temperature. At 75°C ambient, maximum allowable power dissipation drops to 625 mW – (50 × 5.0) = 375 mW. This linear derating ensures junction temperature remains ≤150°C under steady-state conditions.