onsemi BCW65ALT1

Overview

BCW65ALT1 from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for V_CEO = 32 V, I_C = 800 mA, and f_T = 100 MHz, with h_FE = 35–250 (at I_C = 100 mA to 500 mA), used in low-voltage switching and amplification circuits such as LED drivers and signal buffering.

For engineers reviewing the BCW65ALT1 datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain spread at varying collector currents, V_CE(sat) ≤ 0.7 V at I_C = 500 mA/I_B = 50 mA, thermal resistance of 556 °C/W on FR-5 board, and Pb-free SOT-23 compatibility with automated assembly.

Technical Context

This NPN bipolar junction transistor operates in linear and saturated modes, supporting both analog amplification (with noise figure NF = 10 dB at 1 kHz) and digital switching (t_on = 100 ns, t_off = 400 ns). Its f_T = 100 MHz enables RF-capable small-signal use up to VHF band edge.

Designed for surface-mount reliability on FR-5 and alumina substrates, it delivers 225 mW dissipation at 25°C (derating 1.8 mW/°C), with junction temperature range −55°C to +150°C and breakdown ratings V_CBO = 60 V, V_EBO = 5.0 V - confirming suitability for moderate-voltage interface stages.

Key Specifications

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount plastic package with gull-wing leads, footprint compatible with JEDEC TO-236 standard; 2.9 mm × 1.3 mm × 0.95 mm body, 0.65 mm lead pitch.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC847BLT1G and MMBT3904LT1G, the BCW65ALT1 provides uniquely higher continuous current handling (800 mA vs. ≤200 mA) and verified 32 V V_CEO rating - making it the only option among the three qualified for medium-power switching in industrial 24 V control modules.

Availability

BCW65ALT1 is available at Aetrix Electronics and suitable for LED driver circuits, relay interface modules, signal buffering stages, and audio pre-amplifier inputs requiring stable component supply and RoHS-compliant SOT-23 packaging.

Supply support for BCW65ALT1 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 delivering energy-efficient, high-performance silicon solutions for automotive, industrial, cloud, medical, and IoT applications.

The BCW65ALT1 belongs to onsemi's general-purpose bipolar transistor product line, engineered for cost-sensitive, high-volume applications demanding reliable DC switching and small-signal amplification in compact SOT-23 form factor.

FAQ

What is the maximum collector current rating for BCW65ALT1?

The BCW65ALT1 has a maximum continuous collector current (I_C) rating of 800 mAdc at T_A = 25°C. Derating applies above this temperature per the 1.8 mW/°C thermal specification. This rating supports medium-power switching tasks such as driving relays or multiple parallel LEDs, and must be validated against actual board-level thermal performance in the target layout.

Does BCW65ALT1 support Pb-free reflow soldering?

Yes, BCW65ALT1 is offered in a Pb-free SOT-23 package (also marked as BCW65ALT1G), compliant with RoHS Directive 2011/65/EU. It meets J-STD-020 moisture sensitivity level 1 and is qualified for standard lead-free reflow profiles with peak temperatures up to 260°C, as confirmed in onsemi's packaging documentation.

What is the DC current gain (h_FE) range of BCW65ALT1 across operating conditions?

The BCW65ALT1 exhibits h_FE = 35 (min) at I_C = 100 mA/V_CE = 10 V, rising to 100 (min) at I_C = 100 mA/V_CE = 1.0 V, and reaching 250 (max) under same conditions. This wide spread requires circuit-level gain stabilization - typically via emitter degeneration - especially in linear amplification roles where predictable gain is critical.

Can BCW65ALT1 replace BCW65CLT1 in existing designs?

No - BCW65ALT1 and BCW65CLT1 are distinct variants: BCW65ALT1 has h_FE = 35–250, while BCW65CLT1 offers h_FE = 80–630. Substituting BCW65ALT1 for BCW65CLT1 may cause insufficient gain or unstable bias in circuits relying on higher minimum h_FE, particularly at low I_C. Cross-replacement requires full electrical validation.

What is the thermal resistance (R_JA) of BCW65ALT1 on standard FR-5 PCB?

The BCW65ALT1 has a thermal resistance R_JA of 556 °C/W when mounted on an FR-5 board (1.0 × 0.75 × 0.062 in), per the official datasheet. This value assumes no copper pour or thermal vias; adding 1-in² copper area beneath the pad can reduce R_JA by ~20–30%, directly improving maximum allowable power dissipation in thermally constrained layouts.