onsemi BF393ZL1

Overview

BF393ZL1 from onsemi is a high-voltage NPN silicon transistor rated for 300 V_CEO, 500 mA continuous collector current, and 1.5 W power dissipation at T_C = 25°C. It features h_FE of 25–40 at I_C = 1.0–10 mA, f_T ≥ 50 MHz, and V_CE(sat) ≤ 2.0 V at I_C/I_B = 10 - used in flyback switchers, CRT horizontal deflection, and high-voltage linear regulators.

For engineers reviewing the BF393ZL1 datasheet, pinout, applications, or equivalent options, key selection considerations include its 300 V breakdown rating, TO-92 package thermal resistance (R_JC = 83.3°C/W), DC gain range, saturation voltage behavior under pulsed switching, and Pb-free tape-and-reel packaging (2000 units/reel).

Technical Context

The BF393ZL1 operates as a general-purpose high-voltage NPN switching transistor with fixed-emitter configuration and base-controlled conduction. Its design supports stable gain across −55°C to +150°C junction temperature and maintains V_(BR)CEO = 300 V with I_C = 1.0 mA, enabling use in circuits where transient overvoltage immunity is required without external clamping.

It exhibits C_re ≤ 2.0 pF at V_CB = 60 V and f = 1.0 MHz, supporting moderate-frequency switching up to ~50 MHz f_T while maintaining low capacitive loading on driver stages. The device's safe operating area (SOA) is defined by thermal, current, and second-breakdown limits - critical for pulse-width modulated loads with high peak currents.

Key Specifications

Pinout & Package

BF393ZL1 is housed in a Pb-free TO-92 (Case 29-11, Style 1) plastic package with 3 leads, designed for through-hole mounting and manual or wave soldering. The package provides R_JA = 200°C/W (unmounted) and R_JC = 83.3°C/W (case-mounted), and meets JEDEC TO-92 mechanical standards.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar high-voltage NPN transistor applications.

Compared with MPSA42 and 2N5551, the BF393ZL1 offers guaranteed 300 V breakdown with consistent low-saturation performance at medium currents, making it preferred for cost-sensitive, thermally constrained HV switch applications where gain variation is acceptable.

Availability

BF393ZL1 is available at Aetrix Electronics and suitable for switch-mode power supplies, CRT deflection circuits, and industrial relay drivers requiring stable component supply and Pb-free compliance.

Supply support for BF393ZL1 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

onsemi (formerly ON Semiconductor) is a global semiconductor supplier focused on energy-efficient innovation for automotive, industrial, cloud, and intelligent edge applications.

The BF393ZL1 belongs to onsemi's high-voltage bipolar transistor product line, engineered for robustness in mains-connected power conversion and analog signal conditioning where reliability under voltage stress is critical.

FAQ

What is the maximum collector-emitter voltage rating for BF393ZL1?

The BF393ZL1 has a guaranteed minimum collector-emitter breakdown voltage V_(BR)CEO of 300 V at I_C = 1.0 mA and T_A = 25°C. This rating is validated per onsemi's published electrical characteristics table and applies under specified test conditions - not as a recommended continuous operating voltage. Designers must apply derating for temperature, reliability margin, and transient overshoot when using BF393ZL1 in actual circuits.

Is BF393ZL1 compatible with lead-free soldering processes?

Yes, BF393ZL1 is manufactured in a Pb-free TO-92 package and qualified for standard lead-free reflow and wave soldering per J-STD-020 and J-STD-006. The device's maximum junction temperature rating of +150°C supports typical Pb-free peak profiles (up to 260°C for ≤10 seconds), and its thermal resistance values (R_JA = 200°C/W, R_JC = 83.3°C/W) remain valid under Pb-free assembly conditions.

How does the DC current gain (h_FE) of BF393ZL1 vary with collector current?

Per the BF393ZL1 datasheet Figure 1, h_FE peaks near I_C = 10–20 mA at ~40, then declines at higher currents due to high-level injection effects. At I_C = 1.0 mA, h_FE is ≥25; at I_C = 50 mA, it drops to ~20. This nonlinearity must be accounted for in base drive design - especially in linear applications where gain stability affects loop response and distortion.

Can BF393ZL1 replace BF393 in existing designs?

Yes, BF393ZL1 is a Pb-free, tape-and-reel variant of the BF393, sharing identical electrical specifications, TO-92 package dimensions, and pinout (Emitter-Base-Collector). The "ZL1" suffix denotes Pb-free construction and 2000-unit tape-and-reel packaging - no changes to silicon, gain, voltage ratings, or thermal performance. Existing BF393 layouts and schematics are fully compatible with BF393ZL1.

What is the safe operating area (SOA) limitation for BF393ZL1 in pulse applications?

The BF393ZL1 SOA curve (Figure 5) shows three limiting regions: current limit (≤500 mA), thermal limit (1.5 W at T_C = 25°C), and second-breakdown limit (pulse-dependent). For 100 µs pulses, the device supports up to ~2 A at 100 V; for 1 ms pulses, max current drops to ~500 mA at 200 V. Designers must consult the published SOA graph and apply derating for case temperature, duty cycle, and layout thermal impedance when using BF393ZL1 in pulsed switching.