onsemi PN3645_D74Z

Overview

PN3645_D74Z 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_CE(sat) = 0.25 V at I_C = 50 mA / I_B = 2.5 mA, h_FE = 40–300 (depending on operating point), and TO-92 package with emitter-first radial ammo packaging (EOL code D74Z).

For engineers reviewing the PN3645_D74Z 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 suitability for low-to-medium power linear amplification and saturated switching in industrial control and power management circuits.

Technical Context

The PN3645_D74Z operates as a silicon PNP BJT fabricated using Fairchild's Process 63. Its DC current gain (h_FE) varies from 40 at low current (I_C = 0.1 mA) to 100 at I_C = 10 mA and drops to 20 at I_C = 300 mA, indicating optimized gain profile for general-purpose biasing. Saturation characteristics are specified at two points: V_CE(sat) = 0.25 V (I_C = 50 mA, I_B = 2.5 mA) and 0.4 V (I_C = 150 mA, I_B = 15 mA), supporting reliable on-state operation in switch-mode designs.

Switching performance includes t_on = 40 ns, t_off = 100 ns, and t_s = 70 ns under pulsed conditions (V_CC = 30 V, I_C = 300 mA), confirming suitability for medium-speed digital and PWM-driven applications. Small-signal parameters include C_ob = 8.0 pF and h_fe = 2.0 at f = 100 MHz, reflecting limited RF capability but adequate bandwidth for audio and control-frequency signals.

Key Specifications

Pinout & Package

PN3645_D74Z is supplied in the standard TO-92 plastic package with radial lead configuration and emitter-first orientation per EOL code D74Z (Ammo pack, flat side down, adhesive tape on bottom side). Leads are unclipped and straight.

Key Features

Applications

Equivalent & Alternatives

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

Compared with MPSA92 and PN2907A, PN3645_D74Z offers balanced voltage/current capability and cost-effective general-purpose performance, while MPSA92 extends voltage headroom and PN2907A improves gain consistency-making each suitable for distinct reliability or topology requirements without requiring PCB redesign.

Availability

PN3645_D74Z is available at Aetrix Electronics and suitable for relay driver circuits, DC motor control modules, linear regulator pass elements, and LED switching applications requiring stable component supply and consistent TO-92 radial ammo packaging.

Supply support for PN3645_D74Z 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 components before its acquisition by ON Semiconductor in 2016. Its legacy products remain widely deployed in industrial and automotive systems.

The PN3645_D74Z belongs to Fairchild's general-purpose bipolar transistor product line, engineered for cost-sensitive, medium-power amplification and switching tasks in non-automotive industrial equipment where robustness and manufacturability are prioritized over automotive-grade qualification.

FAQ

What is the pin configuration of PN3645_D74Z?

PN3645_D74Z uses a TO-92 package with emitter-first radial ammo orientation (EOL code D74Z): Lead 1 = Emitter, Lead 2 = Base, Lead 3 = Collector. The flat side of the package faces down, and adhesive tape is applied to the bottom side-matching standard pick-and-place feeder requirements for through-hole assembly.

Is PN3645_D74Z RoHS compliant?

PN3645_D74Z was manufactured prior to full RoHS enforcement and does not carry formal RoHS certification. It contains leaded solder terminations and falls under legacy exemption categories. For new designs requiring RoHS compliance, consider ON Semiconductor's NSS series or MMBT2907A as modern alternatives with verified compliance documentation.

What is the maximum power dissipation of PN3645_D74Z at 75°C ambient?

At 75°C ambient, PN3645_D74Z's maximum power dissipation is 375 mW. This is calculated from its 625 mW rating at 25°C and 5.0 mW/°C derating factor: 625 mW − (50°C × 5.0 mW/°C) = 375 mW. Exceeding this risks junction temperature exceeding 150°C, triggering thermal degradation.

Can PN3645_D74Z replace PN2907A in existing designs?

PN3645_D74Z can serve as a functional alternative to PN2907A in many applications due to identical Process 63 origin and overlapping electrical specs, but PN2907A guarantees higher minimum h_FE (100 vs. 40) and tighter parameter distribution. For production-critical analog biasing, PN2907A remains preferred; PN3645_D74Z is suitable for less sensitive switching roles.

What is the typical storage time (t_s) for PN3645_D74Z under switching conditions?

The typical storage time (t_s) for PN3645_D74Z is 70 ns, measured under pulsed test conditions (V_CC = 30 V, I_C = 300 mA, I_B1 = I_B2 = 30 mA). This value reflects minority carrier removal delay during turn-off and directly impacts minimum achievable PWM frequency before distortion.