onsemi BC850BLT1

Overview

BC850BLT1 from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for V_CEO = 45 V, I_C = 100 mA, and h_FE = 200–450 (at I_C = 2 mA, V_CE = 5 V). It delivers low V_CE(sat) ≤ 0.6 V at I_C/I_B = 20, supports f_T = 100 MHz, and is used in signal amplification and switching circuits in industrial control interfaces.

For engineers reviewing the BC850BLT1 datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain range, saturation voltage under defined drive conditions, thermal resistance (R_JA = 556 °C/W on FR-5), ESD robustness (>4000 V HBM), and Pb-free SOT-23 compatibility with automated assembly.

Technical Context

The BC850BLT1 belongs to the BC846–BC850 family of complementary NPN transistors optimized for general-purpose linear and switching applications. Its h_FE binning (B-grade) guarantees minimum 200 and typical 290 at I_C = 2 mA, V_CE = 5 V - a specification validated across −55°C to +150°C operating range.

It exhibits V_BE(sat) = 0.7–0.9 V at I_C/I_B = 20 and C_obo = 4.5 pF at V_CB = 10 V, enabling stable small-signal operation up to 100 MHz. The device uses standard epoxy-molded SOT-23 construction with Moisture Sensitivity Level 1 and Pb-free terminal finish.

Key Specifications

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount plastic package with gull-wing leads; 2.0 mm × 1.25 mm × 0.95 mm footprint; JEDEC-compliant, moisture sensitivity level 1, Pb-free terminations.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC850BLT1, BC847BLT1 offers identical voltage ratings but diverges in h_FE test condition and gain distribution, while MMBT3904LT1G trades 5 V V_CEO margin for superior thermal resistance and broader industry adoption - making it more suitable for cost-sensitive, thermally constrained layouts.

Availability

BC850BLT1 is available at Aetrix Electronics and suitable for industrial sensor interfaces, LED driver circuits, level-shifting logic, and relay driver stages requiring stable component supply, long-term manufacturability, and RoHS-compliant packaging.

Supply support for BC850BLT1 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, sensors, and logic devices for automotive, industrial, and cloud infrastructure markets.

The BC850BLT1 belongs to onsemi's BC846–BC850 family of general-purpose bipolar transistors engineered for reliability and consistency in signal conditioning, switching, and interface applications across harsh industrial environments.

FAQ

What is the maximum continuous collector current rating for BC850BLT1?

The BC850BLT1 has a maximum continuous collector current (I_C) rating of 100 mA at T_A = 25°C. This rating assumes operation on an FR-5 PCB with 225 mW total device dissipation and requires linear derating of 1.8 mW/°C above 25°C ambient. At elevated temperatures or on smaller copper areas, actual usable current must be reduced accordingly to maintain junction temperature below +150°C.

Does BC850BLT1 support Pb-free soldering processes?

Yes, BC850BLT1 features Pb-free terminations and is qualified for lead-free reflow soldering per J-STD-020. Its moisture sensitivity level is rated at MSL 1, meaning it can be stored indefinitely at ≤30°C/85% RH without baking prior to assembly. The device meets RoHS Directive 2011/65/EU and is marked with "G" suffix variants for explicit Pb-free identification.

What is the guaranteed h_FE range for BC850BLT1 at typical operating conditions?

The BC850BLT1 (B-grade) guarantees h_FE between 200 and 450 when tested at I_C = 2.0 mA and V_CE = 5.0 V, TA = 25°C. This binning ensures predictable base drive requirements in low-current amplification and switching applications. At I_C = 10 mA, h_FE remains functional but is not binned - typical values fall within 150–270 per the BC847B/BC850B group specification.

Can BC850BLT1 replace BC847BLT1 in existing designs without modification?

BC850BLT1 and BC847BLT1 share identical SOT-23 package, pinout, and V_CEO/V_CBO/V_EBO ratings, but differ in h_FE test condition: BC850BLT1 is specified at I_C = 2 mA, while BC847BLT1 is specified at I_C = 10 mA. Substitution is electrically viable if the circuit operates near 2 mA collector current; otherwise, verify gain-dependent timing or saturation margins in the target application.

What is the thermal resistance (R_JA) of BC850BLT1 on standard FR-5 PCB?

The BC850BLT1 has a thermal resistance of R_JA = 556 °C/W when mounted on a standard FR-5 PCB (1.0″ × 0.75″ × 0.062″) with no added copper pour. This value reflects worst-case convection-only cooling and requires derating of PD = 225 mW at 25°C ambient. Adding thermal vias or copper pads reduces R_JA, but design validation is required to quantify improvement for BC850BLT1-specific layouts.