onsemi PZT3904

Overview

PZT3904 from ON Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) in SOT-223 package, rated for 40 V V_CEO, 200 mA continuous collector current, 1,000 mW power dissipation at 25°C, and 300 MHz transition frequency - used as amplifier or switch in low-voltage signal conditioning and digital logic interface circuits.

For engineers reviewing the PZT3904 datasheet, pinout, applications, or equivalent options, key selection criteria include thermal performance (R_θJA = 125°C/W), DC current gain (h_FE = 100–300 at I_C = 10 mA), saturation voltage (V_CE(sat) ≤ 0.2 V), and SOT-223 footprint compatibility with high-power PCB layouts.

Technical Context

The PZT3904 operates as a discrete NPN BJT with fixed emitter-base and collector-base junctions, supporting linear amplification up to 100 MHz and switching with 35 ns delay time and 50 ns fall time. Its design targets moderate-speed, medium-current applications where thermal robustness exceeds SOT-23 variants.

Unlike TO-92 and SOT-23 versions, the PZT3904 uses a 4-lead SOT-223 package with an exposed collector tab for enhanced heat dissipation - enabling 1 W power handling and 8.0 mW/°C derating above 25°C, critical for sustained 100 mA operation in ambient temperatures up to 125°C.

Key Specifications

Pinout & Package

SOT-223 (TO-261AA) 4-lead surface-mount package with exposed collector tab (Pin 4) for thermal conduction to PCB copper. Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector, Pin 4 = Collector (tab).

Key Features

Applications

Equivalent & Alternatives

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

Compared with MMBT3904 and 2N3904, the PZT3904 delivers superior thermal performance and higher power capability in a surface-mount format - making it optimal for production-grade industrial controls, power supply feedback, and LED driver circuits requiring long-term reliability at elevated ambient temperatures.

Availability

PZT3904 is available at Aetrix Electronics and suitable for industrial sensor interfaces, microcontroller output drivers, and DC-DC converter feedback circuits requiring stable component supply and consistent SOT-223 thermal performance.

Supply support for PZT3904 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

ON Semiconductor (formerly Fairchild Semiconductor) is a global supplier of energy-efficient semiconductor solutions, specializing in power management, analog, sensing, and connectivity technologies for automotive, industrial, and cloud infrastructure markets.

The PZT3904 belongs to ON Semiconductor's legacy general-purpose transistor family, designed specifically to deliver robust, cost-effective NPN switching and amplification in surface-mount packages optimized for thermal reliability and high-volume manufacturing.

FAQ

What is the maximum continuous collector current rating for the PZT3904?

The PZT3904 has a maximum continuous collector current (I_C) rating of 200 mA at T_A = 25°C. This rating assumes proper PCB thermal management - specifically, soldering the exposed collector tab (Pin 4) to ≥6 cm² of copper pour. At elevated ambient temperatures, current must be reduced per the 8.0 mW/°C derating curve to maintain junction temperature ≤150°C. The PZT3904 supports pulsed currents up to 100 mA with minimal saturation voltage degradation.

Does the PZT3904 have a built-in diode or protection circuitry?

No, the PZT3904 is a discrete NPN bipolar junction transistor with no integrated protection diodes, ESD structures, or current-limiting features. It consists solely of emitter, base, and collector junctions as defined in its datasheet. External components - such as base resistors, flyback diodes across inductive loads, and series current-limiting resistors - must be added per application requirements. The PZT3904 does not include any on-chip ESD protection beyond inherent junction capacitance and breakdown limits specified in the absolute maximum ratings.

What is the pin configuration of the PZT3904 in the SOT-223 package?

The PZT3904 uses a 4-pin SOT-223 (TO-261AA) package with the following pinout: Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector, and Pin 4 = Collector (exposed metal tab). Pins 3 and 4 are internally connected and must both be electrically and thermally tied to the same net - typically the load return or supply rail. The JEDEC-standard land pattern (SOT230P700X180-4BN) requires alignment of the tab to a dedicated thermal pad on the PCB for optimal heat transfer and mechanical stability.

How does the PZT3904 compare to the MMBT3904 in terms of thermal performance?

The PZT3904 significantly outperforms the MMBT3904 thermally: its R_θJA is 125°C/W versus 357°C/W for the MMBT3904, and its power dissipation is 1,000 mW versus 350 mW at 25°C. This results from the PZT3904's larger SOT-223 package with an exposed collector tab that conducts heat directly into PCB copper. In practice, the PZT3904 can sustain 100 mA continuous collector current at 85°C ambient, whereas the MMBT3904 would exceed safe junction temperature under identical conditions. Both share identical electrical parameters at low currents, but thermal headroom defines their functional divergence.

Is the PZT3904 suitable for RF amplifier applications?

Yes, the PZT3904 is suitable for low-power RF amplifier applications up to 100 MHz due to its 300 MHz transition frequency (f_T) and low output capacitance (C_obo = 4.0 pF). It has been characterized for small-signal gain and phase response up to 1 GHz in typical performance curves, though usable gain drops above 100 MHz. Designers should apply proper bias stabilization, impedance matching networks, and decoupling - especially at V_CC - to maintain linearity and prevent oscillation. The PZT3904 is not optimized for high-efficiency RF power amplification but performs reliably in IF stages, sensor signal pre-amplifiers, and clock buffer circuits.