onsemi PN3645_D26Z

Overview

PN3645_D26Z 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, h_FE = 40–300 (at I_C = 0.1–300 mA), V_CE(sat) = 0.25 V (I_C = 50 mA, I_B = 2.5 mA), and TO-92 package. It is commonly used in low-voltage DC power control circuits such as relay drivers and signal inversion stages.

For engineers reviewing the PN3645_D26Z datasheet, pinout, applications, or equivalent options, key selection considerations include its PNP polarity, 60 V breakdown rating, 800 mA absolute max collector current, thermal resistance of 200 °C/W (junction-to-ambient), and tape-and-reel packaging with EOL code D26Z.

Technical Context

The PN3645_D26Z operates as a silicon PNP BJT fabricated on Fairchild's Process 63. Its DC current gain (h_FE) varies significantly with operating point-ranging from 40 at I_C = 0.1 mA to 20 at I_C = 300 mA-indicating optimized use in medium-current linear amplification or saturated switching. The device exhibits V_BE(sat) = 1.0 V at I_C = 50 mA / I_B = 2.5 mA, confirming base drive requirements for reliable turn-on.

Switching performance is characterized by t_on = 40 ns, t_off = 100 ns, and t_s = 70 ns under V_CC = 30 V, I_C = 300 mA conditions. Small-signal h_fe = 2.0 at f = 100 MHz confirms limited RF suitability but adequate bandwidth for audio and digital logic interfacing.

Key Specifications

Pinout & Package

PN3645_D26Z is packaged in TO-92, a through-hole plastic case with three leads. Pin configuration follows standard TO-92 orientation: flat side facing viewer, leads down, left-to-right = Emitter–Base–Collector (E-B-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, PN3645_D26Z offers balanced 60 V/800 mA capability with broad h_FE tolerance-ideal for cost-sensitive industrial switching where moderate voltage headroom and proven process reliability are prioritized over ultra-high gain or extreme voltage ratings.

Availability

PN3645_D26Z is available at Aetrix Electronics and suitable for relay driver circuits, DC motor control modules, LED interface boards, and linear level-shifting applications requiring stable component supply and long-term obsolescence management.

Supply support for PN3645_D26Z 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 legacy products remain widely deployed in industrial and automotive systems.

The PN3645_D26Z belongs to Fairchild's general-purpose bipolar transistor family, engineered for cost-effective amplification and switching in non-critical industrial controls, power supplies, and interface circuits where robustness and manufacturability outweigh ultra-high-frequency or precision requirements.

FAQ

What is the pin configuration of PN3645_D26Z?

PN3645_D26Z uses the standard TO-92 package with Emitter–Base–Collector (E-B-C) pinout when viewed with the flat side facing the user and leads pointing downward. Lead 1 (left) is Emitter, lead 2 (center) is Base, and lead 3 (right) is Collector. This configuration is confirmed in Fairchild's TO-92 packaging documentation and matches the D26Z tape-and-reel orientation specification.

Does PN3645_D26Z support switching at 100 kHz?

Yes, PN3645_D26Z supports switching at 100 kHz in typical saturated-switch configurations. With t_on = 40 ns and t_off = 100 ns, total switching time is ~140 ns-well below the 10 µs period of 100 kHz. However, thermal limits must be observed: at 100% duty cycle, power dissipation must stay within 625 mW (derated above 25°C), so average current should be limited accordingly in PN3645_D26Z designs.

What is the maximum continuous collector current for PN3645_D26Z?

The maximum continuous collector current for PN3645_D26Z is 800 mA at T_A = 25°C, as specified in its Absolute Maximum Ratings table. Operation at this current requires strict thermal management-R_θJA = 200 °C/W means junction temperature rises 160°C above ambient at full current, exceeding the 150°C max rating. Therefore, sustained 800 mA operation is only feasible with heatsinking or reduced ambient temperature, and PN3645_D26Z is typically applied at ≤500 mA for reliability.

Is PN3645_D26Z RoHS compliant?

PN3645_D26Z was manufactured prior to RoHS enforcement deadlines and predates formal RoHS certification by Fairchild. Its datasheet and packaging documentation do not declare RoHS compliance, and legacy TO-92 variants like PN3645_D26Z contain leaded solder terminations. For new designs requiring RoHS compliance, consider modern alternatives such as the NSS60201MR6T1G (SOT-23, RoHS-compliant PNP), while PN3645_D26Z remains viable for legacy repair and non-regulated industrial applications.

Can PN3645_D26Z replace PN2907A in existing designs?

PN3645_D26Z is not a direct replacement for PN2907A. Although both are PNP TO-92 transistors, PN2907A specifies V_CEO = 60 V, I_C = 600 mA, and h_FE = 100–300, while PN3645_D26Z has identical V_CEO but higher I_C (800 mA) and broader h_FE (40–300). Electrical differences in saturation voltage and gain distribution may affect bias stability; thus, validation testing is required before substituting PN3645_D26Z into PN2907A-based circuits.