onsemi PN4250A

Overview

PN4250A from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor designed for amplification and switching in low-to-medium power circuits, with V_CEO = 60 V, I_C = 500 mA continuous, h_FE = 250–700 at I_C = 100 µA, and TO-92 package. It serves in signal conditioning, discrete logic interfaces, and load switching up to 300 mA collector current.

For engineers reviewing the PN4250A datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, DC current gain range, saturation voltage under defined drive conditions, thermal resistance (R_θJA = 200 °C/W), and compatibility with through-hole PCB assembly using standard TO-92 footprints.

Technical Context

The PN4250A operates as a silicon PNP BJT with fixed-emitter biasing capability and linear amplification characteristics validated at V_CE = 5.0 V and I_C = 1.0 mA. Its small-signal parameters include h_fe = 250–800, C_ob = 6.0 pF at V_CB = 5.0 V, and noise figure = 2.0 dB at 1 kHz with 1 kΩ source impedance.

It is rated for operation across –55°C to +150°C junction temperature, with absolute maximum ratings defined by thermal limits (T_J ≤ 150°C) and steady-state dissipation (P_D = 625 mW at 25°C, derated 5.0 mW/°C above). The device uses Fairchild's Process 68 and shares electrical characterization reference with PN200.

Key Specifications

Pinout & Package

PN4250A is housed in a standard through-hole TO-92 plastic package with 3 leads. Pin identification follows JEDEC TO-92 configuration: flat side facing viewer, leads down, left-to-right = Emitter (E), Base (B), Collector (C).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and BC557, the PN4250A delivers balanced performance for mid-range PNP switching and amplification-offering superior gain uniformity versus MPSA92 and higher current capability than BC557-making it optimal for industrial interface circuits demanding both reliability and design margin.

Availability

PN4250A is available at Aetrix Electronics and suitable for relay drivers, audio preamplifiers, logic level shifters, and current mirror references requiring stable component supply and long-term manufacturability.

Supply support for PN4250A 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 devices before its acquisition by ON Semiconductor in 2016.

The PN4250A belongs to Fairchild's legacy general-purpose bipolar transistor family, engineered for cost-sensitive industrial and consumer applications requiring reliable amplification and switching in through-hole assemblies.

FAQ

What is the maximum continuous collector current rating for PN4250A?

The PN4250A has a maximum continuous collector current (I_C) rating of 500 mA at T_A = 25°C. This rating assumes proper PCB thermal management; derating applies above 25°C at 5.0 mW/°C. At elevated ambient temperatures or in enclosed enclosures, actual usable current must be reduced to maintain junction temperature ≤150°C. The PN4250A datasheet specifies this limit under steady-state conditions-not pulsed operation.

Is PN4250A a PNP or NPN transistor?

PN4250A is a PNP bipolar junction transistor. Its polarity is confirmed by absolute maximum ratings (V_CEO = –60 V in conventional notation), terminal labeling (Emitter, Base, Collector in TO-92 order E-B-C), and electrical characteristics including negative V_BE turn-on behavior and current flow direction from emitter to collector. This distinguishes it from NPN counterparts like PN2222A and confirms its use in high-side switching or inverted gain stages.

What is the typical DC current gain (h_FE) of PN4250A at low collector current?

The PN4250A exhibits a DC current gain (h_FE) ranging from 250 to 700 when tested at V_CE = 5.0 V and I_C = 100 µA. This wide gain band reflects process variation across production lots but ensures sufficient drive margin for saturated switching at low base currents. Designers should use the minimum value (250) for worst-case base resistor calculations to guarantee turn-on across all units.

Does PN4250A have a documented noise figure specification?

Yes, the PN4250A has a specified noise figure of 2.0 dB under two test conditions: first at V_CE = 5.0 V, I_C = 250 µA, R_S = 1.0 kΩ, f = 1.0 kHz, BW = 150 Hz; second at V_CE = 5.0 V, I_C = 20 µA, R_S = 10 kΩ, same frequency and bandwidth. This makes the PN4250A suitable for low-noise preamplifier stages where signal integrity at audio frequencies is critical.

What package type is used for PN4250A and how are its leads arranged?

PN4250A uses the TO-92 plastic package with three leads. When oriented with the flat side facing the viewer and leads pointing downward, the left-to-right lead order is Emitter (E), Base (B), Collector (C). This configuration matches JEDEC standard TO-92 pinout and is verified in Fairchild's packaging documentation, tape-and-reel drawings, and mechanical dimension sheets dated January 2000, Rev. B.