onsemi PN4917

Overview

PN4917 from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor (BJT) designed for amplification and switching in low-power analog and digital circuits, with confirmed V_CEO = 30 V, I_C = 200 mA continuous, h_FE = 100–300 at I_C = 100 µA to 50 mA, and TO-92 package. It serves in signal conditioning stages of sensor interfaces and discrete logic-level translators.

For engineers reviewing the PN4917 datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, 30 V breakdown rating, saturation voltage behavior under 50 mA load, thermal resistance (R_θJA = 200 °C/W), and compatibility with legacy 2N3906-based designs.

Technical Context

The PN4917 operates as a silicon PNP BJT fabricated on Fairchild's Process 66, sharing electrical characteristics with the 2N3906 but specified independently. Its DC current gain (h_FE) varies from 100 at 100 µA to 30 at 50 mA, and it delivers V_CE(sat) ≤ 0.30 V at I_C = 50 mA / I_B = 5 mA - confirming suitability for saturated-switching roles.

Small-signal parameters include f_T ≈ 250 MHz (inferred from h_fe = 4.5 at 100 MHz and typical PNP scaling), C_ob = 4.5 pF, and NF = 4.0 dB at 100 µA/1 kHz source impedance - supporting audio-frequency amplification and low-noise preamplifier use cases where bandwidth up to ~50 MHz is sufficient.

Key Specifications

Pinout & Package

PN4917 is housed in a standard through-hole TO-92 package (3-lead, plastic, straight lead configuration). Pin identification follows JEDEC TO-92 outline: when flat side faces user and leads point downward, left-to-right pin order is 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 2N3906 and BC557, PN4917 offers identical switching performance and thermal limits to 2N3906 but lacks formal AEC-Q200 status, while providing higher I_C headroom than BC557 at the cost of wider h_FE variation - making it optimal for cost-sensitive industrial prototypes where full qualification isn't required.

Availability

PN4917 is available at Aetrix Electronics and suitable for industrial sensor interfaces, discrete logic-level translation, and low-power audio preamplifier designs requiring stable component supply and long-term obsolescence management.

Supply support for PN4917 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 designer and manufacturer of analog and discrete semiconductors, acquired by ON Semiconductor in 2016; its legacy products remain widely used in industrial and consumer electronics.

PN4917 belongs to Fairchild's general-purpose bipolar transistor family targeting cost-effective, through-hole solutions for amplification and switching in non-automotive, non-military applications - emphasizing manufacturability, thermal predictability, and cross-compatibility with industry-standard footprints.

FAQ

What is the maximum continuous collector current rating for PN4917?

The PN4917 has a maximum continuous collector current (I_C) rating of 200 mA at T_A = 25°C. However, practical design limits are governed by power dissipation: with P_D = 625 mW and R_θJA = 200 °C/W, sustained operation above ~100 mA requires careful thermal layout or derating above 25°C ambient. The PN4917 datasheet specifies 100 mA as the typical operational limit for general-purpose switching.

Is PN4917 pin-compatible with 2N3906?

Yes, PN4917 is pin-compatible with 2N3906 - both use the TO-92 package with identical lead assignment (Emitter-Base-Collector, left-to-right with flat side facing user). Electrical specifications including V_CEO, V_CE(sat), h_FE, and switching times match within datasheet tolerances, enabling direct substitution in existing 2N3906 layouts without PCB modification. The PN4917 datasheet explicitly references 2N3906 for characteristics.

What is the typical noise figure of PN4917 and at what conditions is it measured?

The PN4917 has a noise figure (NF) of 4.0 dB at V_CE = 5.0 V, I_C = 100 µA, R_S = 1.0 kΩ, and f = 100 MHz, and 6.0 dB at I_C = 1.0 mA with R_S = 100 Ω. These values confirm suitability for low-noise preamplifier stages in audio and RF front-ends where sub-10 dB NF is acceptable. The PN4917's NF performance is directly specified in its official Fairchild datasheet under SMALL SIGNAL CHARACTERISTICS.

Does PN4917 support high-speed switching applications?

Yes, PN4917 supports high-speed switching with documented t_on = 40 ns, t_off = 150 ns, and t_s = 140 ns at V_CC = 10 V and I_C = 50 mA. These values enable reliable operation up to ~2 MHz square-wave frequencies in saturated-switch configurations. The PN4917's rb'Cc = 50 ps further confirms its suitability for RF-coupled switching where parasitic time constants must remain minimal.

What is the operating junction temperature range for PN4917?

The PN4917 has an operating and storage junction temperature range (T_J, T_stg) of −55°C to +150°C, as defined in its Absolute Maximum Ratings table. This wide range supports deployment in industrial environments with uncontrolled ambient conditions. The 150°C maximum junction temperature aligns with Fairchild's Process 66 thermal design rules and is validated by the device's R_θJC = 83.3 °C/W and R_θJA = 200 °C/W ratings.