onsemi PN4275

Overview

PN4275 from Fairchild Semiconductor is an NPN switching transistor designed for high-speed saturated switching at up to 100 mA collector current, with V_CEO = 15 V, V_CBO = 40 V, and t_on/t_off ≤ 12 ns. It features low V_CE(sat) (0.20 V @ I_C = 10 mA, I_B = 1 mA) and is commonly used in digital logic interface, pulse generation, and small-signal switching circuits.

For engineers reviewing the PN4275 datasheet, pinout, applications, or equivalent options, key selection criteria include saturation voltage at defined drive conditions, thermal resistance (R_θJA = 357 °C/W), TO-92 package compatibility, and verified switching performance at 100 MHz test frequency.

Technical Context

The PN4275 operates as a discrete bipolar junction transistor optimized for fast turn-on/turn-off transitions under saturated switching conditions. Its h_FE ranges from 35–120 depending on I_C, and it supports V_BE(sat) as low as 0.72 V at I_C = 10 mA / I_B = 1 mA, enabling efficient base drive in low-voltage logic interfaces.

Thermal design is constrained by R_θJA = 357 °C/W and P_D = 350 mW at T_A = 25 °C, derating at 2.8 mW/°C above ambient. The device is rated for operation from –55 °C to +150 °C junction temperature and uses Process 21 fabrication.

Key Specifications

Pinout & Package

PN4275 is housed in a standard through-hole TO-92 package with 3 leads. Pin identification follows JEDEC TO-92 outline: flat side facing viewer, leads down, left-to-right = Emitter–Base–Collector (E-B-C). This configuration is confirmed in Fairchild's packaging diagrams and tape-and-reel documentation (EOL code D26Z/D74Z).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching transistor applications.

Compared with PN2222A and BC547B, the PN4275 offers the fastest documented switching speed (12 ns) within its voltage class, making it uniquely suitable for high-fidelity pulse generation where edge sharpness is critical-though its 15 V V_CEO limits use in higher-rail systems.

Availability

PN4275 is available at Aetrix Electronics and suitable for logic-level interface driver, digital pulse generator, and low-power relay driver applications requiring stable component supply and legacy TO-92 footprint compatibility.

Supply support for PN4275 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, acquired by ON Semiconductor in 2016.

The PN4275 belongs to Fairchild's legacy general-purpose NPN transistor family, engineered for cost-sensitive, high-volume saturated switching in consumer, industrial, and computing peripherals.

FAQ

What is the maximum continuous collector current rating for PN4275?

The PN4275 has an absolute maximum continuous collector current (I_C) of 200 mA per its Absolute Maximum Ratings table. However, the device is specifically characterized and recommended for high-speed saturated switching up to 100 mA, as stated in the product description and supported by electrical test conditions across h_FE, V_CE(sat), and switching parameters. Operating continuously near 200 mA requires careful thermal management due to its R_θJA of 357 °C/W.

Does PN4275 have the same pinout as PN2222A?

Yes, PN4275 shares the identical TO-92 E-B-C (Emitter–Base–Collector) pinout with PN2222A when viewed with the flat side facing the user and leads pointing downward. This pin compatibility is confirmed in Fairchild's packaging documentation and enables direct substitution in many legacy designs-though electrical differences (e.g., V_CEO, switching speed) must be validated for functional equivalence in the target circuit.

What is the typical V_BE(sat) for PN4275 at I_C = 10 mA?

The typical V_BE(sat) for PN4275 at I_C = 10 mA and I_B = 1.0 mA is 0.72 V, as specified in the "ON CHARACTERISTICS" section of the datasheet. This value is measured at T_A = 25 °C and reflects the base-emitter voltage required to achieve full saturation under those conditions-critical for calculating base resistor values in driving circuits.

Can PN4275 be used in linear amplifier applications?

The PN4275 is explicitly designed and characterized for high-speed saturated switching-not linear amplification. Its h_FE variation (35–120), limited f_T data, and lack of small-signal linearity specifications indicate it is not optimized for analog gain stages. For linear operation, Fairchild's complementary PN4274 (PNP) or purpose-built amplifiers like the 2N3904 are more appropriate choices.

Is PN4275 RoHS compliant?

PN4275 was manufactured prior to RoHS enforcement deadlines and predates standardized lead-free compliance labeling. Original Fairchild documentation does not declare RoHS status for this part. For new designs requiring RoHS compliance, consider modern alternatives such as the BC547B (RoHS-compliant, TO-92) or MMBT2222ALT1G (SOT-23, RoHS-compliant), both offering comparable NPN switching functionality.