onsemi SBCX19LT1

Overview

SBCX19LT1 from onsemi is an NPN general-purpose bipolar junction transistor (BJT) in SOT-23 package, rated for 45 V_CEO, 500 mA continuous collector current, and 225 mW power dissipation on FR-5 board at 25°C. It delivers DC current gain (h_FE) of 100–600 at I_C = 100 mA and V_CE = 1.0 V, with V_CE(sat) ≤ 0.62 V at I_C = 500 mA / I_B = 50 mA - suitable for low-voltage switching in portable power management and signal amplification stages.

For engineers reviewing the SBCX19LT1 datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/I_C ratings, SOT-23 thermal derating behavior, h_FE consistency across I_C = 100–500 mA, and compatibility with 3.3 V/5 V logic-driven base control in discrete amplifier or load-switch designs.

Technical Context

The SBCX19LT1 operates as a single NPN silicon BJT optimized for linear amplification and saturated switching. Its electrical behavior is defined by three critical DC parameters: V_(BR)CEO = 45 V (min), I_C = 500 mA (max), and h_FE = 100–600 (measured at V_CE = 1.0 V, T_A = 25°C). Thermal performance is specified for two board types: FR-5 (R_JA = 556°C/W) and alumina substrate (R_JA = 417°C/W).

It features a fixed terminal assignment (Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector) and supports operation from −55°C to +150°C junction temperature. The device exhibits V_BE(on) ≤ 1.2 V at I_C = 500 mA and V_CE = 1.0 V, with leakage currents limited to I_CBO ≤ 100 nA (25°C) and ≤ 5.0 µA (150°C).

Key Specifications

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount plastic package with gull-wing leads; 3-terminal configuration optimized for automated placement and reflow soldering on high-density PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC847BWT1G and MMBT3904LT1G, the SBCX19LT1 provides superior current drive (500 mA vs. ≤200 mA) and wider h_FE range at high I_C, making it preferable for robust load switching - though its gain variation at low I_C is less tightly controlled than BC847BWT1G.

Availability

SBCX19LT1 is available at Aetrix Electronics and suitable for LED driver circuits, low-voltage power switches, audio pre-amplifier stages, and industrial sensor interfaces requiring stable component supply and consistent parametric performance across production batches.

Supply support for SBCX19LT1 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 IoT applications.

The SBCX19LT1 belongs to onsemi's general-purpose bipolar transistor product line, designed for cost-effective, reliable discrete switching and amplification in space-constrained, thermally demanding applications.

FAQ

What is the maximum collector-emitter voltage rating for the SBCX19LT1?

The SBCX19LT1 has a guaranteed minimum V_(BR)CEO of 45 Vdc at I_C = 10 mA and I_B = 0. This rating applies under open-base conditions and defines the absolute maximum voltage that can be applied between collector and emitter without risking avalanche breakdown. Exceeding this value may cause irreversible device damage, and derating is recommended for long-term reliability in high-temperature environments. The SBCX19LT1 datasheet confirms this parameter in the "OFF CHARACTERISTICS" table.

Does the SBCX19LT1 support operation at elevated temperatures?

Yes, the SBCX19LT1 is rated for junction and storage temperatures from −55°C to +150°C. Its thermal resistance (R_JA) is 556°C/W on FR-5 board, meaning it can safely dissipate 225 mW at 25°C ambient - with linear derating of 1.8 mW/°C above that point. At 100°C ambient, usable power drops to ~113 mW. This makes the SBCX19LT1 suitable for under-hood automotive modules and industrial controls where ambient temperatures exceed 85°C.

What is the typical DC current gain (h_FE) of the SBCX19LT1 at 500 mA collector current?

At I_C = 500 mA and V_CE = 1.0 Vdc, the SBCX19LT1 exhibits a minimum h_FE of 40, with no upper limit specified in the datasheet. This contrasts with its 100–600 range at I_C = 100 mA. The reduction reflects inherent BJT physics at high current density. Designers must verify base drive sufficiency using the 40× minimum gain to ensure saturation under worst-case conditions - a key requirement for reliable switching in the SBCX19LT1's intended applications.

Is the SBCX19LT1 pin-compatible with other SOT-23 NPN transistors like the MMBT3904?

No, the SBCX19LT1 is not pin-compatible with the MMBT3904. While both use SOT-23 packages, the SBCX19LT1 follows Style 6 pinout (Pin 1 = Base, Pin 2 = Emitter, Pin 3 = Collector), whereas the MMBT3904 uses Style 1 (Pin 1 = Emitter, Pin 2 = Base, Pin 3 = Collector). Swapping them without PCB revision will reverse bias conditions and prevent proper operation. Always confirm pinout diagrams in the respective datasheets - the SBCX19LT1 marking diagram explicitly labels Pin 1 as Base.

What does the 'U1' marking on the SBCX19LT1 indicate?

Per the official onsemi datasheet, the 'U1' marking on the SBCX19LT1 identifies the specific device variant within the BCX17/18/19 family and confirms it as the NPN version (BCX19LT1). This marking appears on the top surface of the SOT-23 package and is used for visual identification during assembly and inspection. It is distinct from date codes or Pb-free indicators, which appear elsewhere on the package per the ordering information section of the SBCX19LT1 datasheet.