onsemi BC558BTAR

Overview

BC558BTAR from ON Semiconductor is a PNP epitaxial silicon transistor in TO-92 package, rated for V_CEO = −30 V, I_C = −100 mA, and h_FE = 200–450 (Class B), used in low-noise audio preamplifier stages and general-purpose switching circuits.

For engineers reviewing the BC558BTAR datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain consistency at −2 mA collector current, low V_BE(on) (−600 to −750 mV), noise figure ≤10 dB at 1 kHz, and thermal resistance of 250 °C/W in standard FR-4 PCB layout.

Technical Context

This device operates as a medium-gain, low-noise PNP bipolar junction transistor optimized for linear amplification and saturated switching. Its h_FE classification (B) ensures predictable current amplification between −2 mA and −10 mA collector currents, with V_CE(sat) ≤ −300 mV at I_C = −10 mA / I_B = −0.5 mA.

Designed for compatibility with complementary NPN types (e.g., BC548), it supports dual-rail amplifier topologies and discrete bias networks. The −5 V emitter-base breakdown (V_EBO) and 6 pF output capacitance (C_ob) support stable operation up to mid-audio frequencies without unintended resonance.

Key Specifications

Pinout & Package

BC558BTAR is housed in a JEDEC TO-92 molded plastic package with straight leads and standard 3-pin configuration. Package dimensions comply with TO-92 mechanical specifications (0.200″ lead spacing, 4.5 mm × 4.0 mm body).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP transistor applications.

Compared with BC558BTAR, BC558BTA offers identical performance in bulk-handling form, while BC557BTA extends voltage capability by 50% without compromising gain or noise - enabling design reuse across multiple supply domains.

Availability

BC558BTAR is available at Aetrix Electronics and suitable for audio preamplifiers, discrete switching circuits, and complementary pair amplifier designs requiring stable component supply and long-term manufacturability.

Supply support for BC558BTAR 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 is a global semiconductor manufacturer specializing in energy-efficient power and signal management solutions, with roots in Fairchild Semiconductor's legacy discrete portfolio.

The BC558BTAR belongs to the BC556–BC560 PNP transistor family, designed for cost-sensitive, high-reliability analog and switching applications in consumer, industrial, and communications equipment.

FAQ

What is the maximum collector-emitter voltage rating for BC558BTAR?

The BC558BTAR has a maximum collector-emitter voltage (V_CEO) rating of −30 V. This value is confirmed in the Absolute Maximum Ratings table of the official datasheet and defines the upper limit for safe operation in common-emitter configurations. Exceeding this voltage risks irreversible breakdown. The BC558BTAR must not be used in circuits where V_CE approaches or exceeds −30 V under any operating condition, including transient spikes.

Is BC558BTAR pin-compatible with BC548 or other complementary NPN transistors?

Yes, BC558BTAR uses the same TO-92 package and pinout (Collector–Base–Emitter) as BC548, making it physically pin-compatible in complementary pair designs. However, polarity reversal means external circuit connections must be adapted - e.g., BC558BTAR emitter connects to V_CC, while BC548 emitter connects to ground. No PCB layout change is needed, but schematic polarity and bias network orientation must be inverted.

What is the typical noise figure of BC558BTAR and under what conditions is it measured?

The BC558BTAR has a noise figure (NF) of ≤10 dB, measured at V_CE = −5 V, I_C = −200 μA, f = 1 kHz, and R_G = 2 kΩ. This specification applies specifically to the BC558 variant (not BC556/BC557), confirming its suitability for low-noise small-signal amplification. The value represents worst-case performance; typical units measure closer to 2–5 dB under identical conditions.

Does BC558BTAR have a specified current gain bandwidth product (f_T)?

Yes, BC558BTAR has a current gain–bandwidth product (f_T) of 150 MHz, measured at V_CE = −5 V, I_C = −10 mA, and f = 10 MHz. This parameter indicates the frequency at which short-circuit current gain drops to unity and confirms usable small-signal amplification up to approximately 10–15 MHz in well-designed common-emitter stages with proper decoupling and layout.

What packaging format does BC558BTAR use and how does it differ from BC558BTA?

BC558BTAR uses tape-and-reel packaging (TR), optimized for automated SMT placement despite being a through-hole TO-92 device. BC558BTA uses ammo packing, intended for manual or semi-automated insertion. Both share identical die, electrical specs, and marking (BC558B), differing only in carrier format - no performance or reliability distinction exists between BC558BTAR and BC558BTA.