onsemi PN3645_J05Z

Overview

PN3645_J05Z from Fairchild Semiconductor is a PNP general-purpose bipolar junction transistor (BJT) designed for amplification and switching applications up to 500 mA collector current. It features V_CEO = 60 V, V_CB0 = 60 V, V_EB0 = 5.0 V, continuous I_C = 800 mA, and operates across –55°C to +150°C. It is commonly used in low-voltage power switching, signal inversion, and discrete logic interface circuits.

For engineers reviewing the PN3645_J05Z datasheet, pinout, applications, or equivalent options, key selection considerations include its TO-92 package, PNP polarity, DC current gain (h_FE = 40–300), saturation voltage (V_CE(sat) = 0.25–0.4 V), and thermal resistance (R_θJA = 200°C/W).

Technical Context

The PN3645_J05Z is fabricated using Fairchild's Process 63, optimized for general-purpose linear amplification and saturated switching. Its h_FE varies with operating point-40 at I_C = 0.1 mA, rising to 300 at I_C = 10 mA-and maintains usable gain up to 200 MHz small-signal frequency (h_fe = 2.0 at f = 100 MHz). It supports fast switching with t_on = 40 ns and t_off = 100 ns under specified pulse conditions.

Thermal design relies on its R_θJC = 83.3°C/W and R_θJA = 200°C/W ratings, with maximum power dissipation of 625 mW at 25°C (derated 5.0 mW/°C above ambient). The device is rated for operation up to 150°C junction temperature and storage down to –55°C, making it suitable for industrial and automotive-adjacent environments where moderate thermal stress occurs.

Key Specifications

Pinout & Package

PN3645_J05Z is housed in a TO-92 plastic package with straight leads and no lead clip (EOL code J05Z), per Fairchild's standard bulk packaging specification. The device uses the conventional B-E-C pinout configuration when viewed with flat side facing outward and leads pointing downward.

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, PN3645_J05Z delivers balanced performance across voltage (60 V), current (800 mA), gain (40–300), and thermal capability (150°C T_J)-making it the preferred choice for mid-power industrial switching and general-purpose amplification where reliability and margin matter.

Availability

PN3645_J05Z is available at Aetrix Electronics and suitable for relay drivers, small DC motor controllers, discrete logic inverters, and linear audio pre-amplifiers requiring stable component supply and long-lifecycle support.

Supply support for PN3645_J05Z 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. Its discrete transistors remain widely deployed in industrial and legacy systems.

The PN3645_J05Z belongs to Fairchild's general-purpose PNP BJT family, engineered for cost-effective, thermally robust amplification and switching in non-automotive industrial equipment and consumer electronics.

FAQ

What is the maximum continuous collector current for PN3645_J05Z?

The PN3645_J05Z supports a maximum continuous collector current of 800 mA at 25°C ambient, as specified in its Absolute Maximum Ratings table. Derating applies above 25°C per the 5.0 mW/°C thermal coefficient. This rating enables use in medium-power switching applications such as relay drivers and small motor controls without external heatsinking under typical board conditions.

Is PN3645_J05Z compatible with TO-92 socket footprints?

Yes, PN3645_J05Z uses the standard TO-92 package with straight leads and no lead clip (EOL code J05Z), matching industry-standard TO-92 socket and PCB footprint dimensions. Its pinout is Emitter-Base-Collector when viewed with the flat side facing outward and leads pointing down, ensuring mechanical and layout compatibility with existing TO-92-based designs.

What is the typical DC current gain (h_FE) of PN3645_J05Z at 10 mA collector current?

At V_CE = 10 V and I_C = 10 mA, the PN3645_J05Z exhibits a typical DC current gain (h_FE) of 100, with a minimum of 100 and maximum of 240 per the Electrical Characteristics table. This gain value supports stable biasing in common-emitter amplifier and switch driver configurations without excessive base drive current.

Does PN3645_J05Z have documented avalanche capability?

No, the PN3645_J05Z datasheet does not specify or characterize avalanche energy rating (E_AS) or ruggedness under inductive switching. It is rated for V_CEO = 60 V under DC conditions only. For inductive load switching, external protection (e.g., flyback diodes) is required to prevent secondary breakdown, as confirmed by Fairchild's application guidance for general-purpose BJTs.

Can PN3645_J05Z be used as a direct replacement for PN2907A?

The PN3645_J05Z shares functional similarity with the PN2907A-both are PNP general-purpose transistors-but they differ in process, gain profile, and thermal specs. While the datasheet references PN2907A for characteristics, PN3645_J05Z has higher I_C (800 mA vs. 600 mA) and distinct h_FE behavior. It is not a drop-in replacement without circuit validation, especially in precision bias or high-temperature applications.