onsemi BC859BLT3

Overview

BC859BLT3 from onsemi is a PNP silicon general-purpose transistor in SOT-23 package, rated for −30 V V_CEO, −30 V V_CBO, −5.0 V V_EBO, −100 mA I_C, and 220–520 h_FE (at I_C = −2.0 mA, V_CE = −5.0 V). It delivers low V_CE(sat) of −0.3 V (I_C = −10 mA, I_B = −0.5 mA) and supports signal switching and amplification in compact DC-DC bias networks.

For engineers reviewing the BC859BLT3 datasheet, pinout, applications, or equivalent options, key selection criteria include its PNP polarity, −30 V breakdown ratings, SOT-23 thermal performance (R_JA = 556 °C/W on FR-5), h_FE grade B/C binning, and Pb-free tape-and-reel packaging (10,000 units).

Technical Context

The BC859BLT3 operates as a discrete bipolar junction transistor with fixed PNP polarity and base-emitter forward biasing. Its electrical behavior is defined by V_BE(on) = −0.75 V (I_C = −10 mA), V_CE(sat) ≤ −0.65 V at high drive (I_C = −100 mA, I_B = −5.0 mA), and f_T = 100 MHz under standard test conditions (I_C = −10 mA, V_CE = −5.0 V).

Thermal design relies on its SOT-23 footprint: total device dissipation is 225 mW on FR-5 board (derated 1.8 mW/°C above 25°C), with R_JA = 556 °C/W. Junction temperature range spans −55°C to +150°C, supporting industrial ambient operation without forced cooling in low-power linear or switching roles.

Key Specifications

Pinout & Package

SOT-23 (TO-236AB) package with 3-pin surface-mount configuration; standardized footprint (2.90 mm × 1.30 mm × 1.00 mm) and JEDEC-compliant lead pitch (1.90 mm). RoHS-compliant, Pb-free construction.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC857BLT3 and BC859CLT3, the BC859BLT3 offers optimal cost-performance balance for 24 V-class PNP switching where −30 V breakdown suffices and moderate h_FE variation is acceptable; it avoids over-spec'ing voltage rating or gain while maintaining full SOT-23 compatibility.

Availability

BC859BLT3 is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, DC-DC converter bias networks, overvoltage protection sensing, and discrete amplifier stages requiring stable component supply and RoHS-compliant packaging.

Supply support for BC859BLT3 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 specializing in energy-efficient power management, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC859BLT3 belongs to the BC856ALT1 Series of general-purpose PNP transistors designed for cost-sensitive, space-constrained applications demanding reliable DC switching and amplification in SOT-23 format.

FAQ

What is the maximum collector-emitter voltage rating for BC859BLT3?

The BC859BLT3 has a guaranteed V_CEO rating of −30 V at T_A = 25°C. This specifies the maximum reverse-biased voltage between collector and emitter before breakdown occurs. Exceeding this value risks permanent damage, especially under elevated temperature or transient conditions. The BC859BLT3 datasheet confirms this rating applies specifically to the BC858/BC859 group within the BC856ALT1 Series.

Does BC859BLT3 support Pb-free reflow soldering processes?

Yes, BC859BLT3 is manufactured in a Pb-free SOT-23 package compliant with JEDEC J-STD-020 moisture sensitivity level 1 and RoHS Directive 2011/65/EU. Its termination finish supports standard lead-free reflow profiles (peak temperature ≤ 260°C), and the "G" suffix variant (BC859BLT3G) explicitly denotes Pb-free construction. The BC859BLT3 datasheet states Pb-free packages are available and validated for automated assembly.

What is the typical DC current gain (h_FE) of BC859BLT3 at I_C = −2.0 mA?

The BC859BLT3 is binned as a Grade B device, with h_FE guaranteed between 220 and 520 at I_C = −2.0 mA and V_CE = −5.0 V. Typical h_FE falls near the center of this range, approximately 370. This gain specification is confirmed in the Electrical Characteristics table of the BC856ALT1 Series datasheet, which explicitly lists BC859 variants under the same test conditions.

Can BC859BLT3 be used in audio-frequency amplifier stages?

Yes, BC859BLT3 supports audio-frequency amplification due to its 100 MHz f_T and low noise figure of 4.0 dB (I_C = −0.2 mA, f = 1 kHz). Its h_FE stability and V_BE(on) consistency (−0.75 V at I_C = −10 mA) enable predictable small-signal gain in common-emitter configurations up to ~10 MHz. The BC859BLT3 datasheet includes noise and frequency response curves validating its suitability for line-level preamplifier use.

What is the thermal resistance (R_JA) of BC859BLT3 on FR-5 board?

The BC859BLT3 exhibits a thermal resistance of R_JA = 556 °C/W when mounted on a standard FR-5 PCB (1.0 × 0.75 × 0.062 in). This value is measured at T_A = 25°C and defines the temperature rise per watt of dissipated power. Derating is required at 1.8 mW/°C above 25°C, limiting usable power to 225 mW at room temperature. This R_JA is documented in the Thermal Characteristics section of the BC856ALT1 Series datasheet.