onsemi BC849BLT3

Overview

BC849BLT3 from onsemi is an NPN silicon general-purpose transistor in SOT-23 package, rated for V_CEO = 30 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) = 0.25 V (I_C = 10 mA, I_B = 0.5 mA) and f_T = 100 MHz, supporting signal amplification and switching in compact consumer and industrial control circuits.

For engineers reviewing the BC849BLT3 datasheet, pinout, applications, or equivalent options, key selection considerations include its 30 V V_CEO, 200–450 DC current gain range, SOT-23 thermal performance (P_D = 225 mW on FR-5), ESD robustness (>4000 V HBM), and compatibility with Pb-free reflow processes.

Technical Context

The BC849BLT3 belongs to onsemi's BC846–BC850 family of complementary NPN/PNP general-purpose transistors optimized for cost-sensitive, space-constrained linear and switching applications. Its design emphasizes consistent h_FE grouping (B-grade), stable V_BE(on) (660–700 mV at I_C = 2 mA), and low C_obo = 4.5 pF for predictable small-signal behavior.

It operates across −55°C to +150°C junction temperature, with thermal resistance R_JA = 556°C/W on FR-5 board and 417°C/W on alumina substrate. The device supports both analog amplification (NF = 4.0 dB at 1 kHz) and digital switching (V_CE(sat) ≤ 0.6 V up to I_C = 100 mA).

Key Specifications

Pinout & Package

SOT-23 (Case 318, Style 6) surface-mount package with 1.0 mm × 1.4 mm footprint, 0.95 mm height, and gull-wing leads. Designed for automated placement and reflow soldering per JEDEC standards.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC849CLT3 and MMBT3904LT3G, the BC849BLT3 provides a balanced trade-off of gain consistency (200–450), low-noise operation (4.0 dB), and proven reliability in high-volume consumer PCBs-making it ideal for cost-driven, space-constrained signal conditioning and switching where moderate gain suffices.

Availability

BC849BLT3 is available at Aetrix Electronics and suitable for LED driver circuits, microcontroller GPIO expansion, low-voltage power switching, and level translation interfaces requiring stable component supply and long-term manufacturability.

Supply support for BC849BLT3 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, sensing, and connectivity solutions for automotive, industrial, cloud, and consumer markets.

The BC849BLT3 belongs to onsemi's BC846–BC850 series of general-purpose transistors designed for high-reliability, low-cost linear amplification and digital switching in space-constrained PCBs.

FAQ

What is the maximum continuous collector current rating for BC849BLT3?

The BC849BLT3 has a maximum continuous collector current (I_C) rating of 100 mA at T_A = 25°C. Derating applies above 25°C at 1.8 mW/°C on FR-5 board. This rating supports typical signal switching and low-power driver applications without external heat sinking under standard ambient conditions. The BC849BLT3 must not be operated beyond this limit to ensure long-term reliability and avoid thermal runaway.

Does BC849BLT3 support Pb-free reflow soldering?

Yes, the BC849BLT3 is manufactured in a Pb-free SOT-23 package compliant with RoHS Directive 2011/65/EU and qualified for lead-free reflow profiles. Its moisture sensitivity level is rated at MSL Level 1, meaning it can be stored indefinitely at ≤30°C/85% RH without baking prior to assembly. The BC849BLT3 meets J-STD-020 requirements for peak reflow temperatures up to 260°C.

What is the DC current gain (h_FE) range for BC849BLT3?

The BC849BLT3 is binned as a "B" grade device with h_FE = 200–450 when measured at I_C = 2.0 mA and V_CE = 5.0 V. This gain range is tighter than the "A" grade (110–220) and looser than the "C" grade (420–800), making the BC849BLT3 suitable for applications requiring predictable but not ultra-high gain, such as buffered sensor interfaces and logic-level translators.

What is the collector-emitter saturation voltage (V_CE(sat)) for BC849BLT3?

The BC849BLT3 exhibits V_CE(sat) ≤ 0.25 V when operated at I_C = 10 mA and I_B = 0.5 mA (I_C/I_B = 20), and ≤ 0.6 V at I_C = 100 mA and I_B = 5.0 mA. These low saturation voltages minimize conduction losses in switching applications, allowing efficient operation in battery-powered devices and 3.3 V logic-controlled loads. The BC849BLT3 maintains this performance across its full operating temperature range.

Is BC849BLT3 suitable for low-noise amplifier applications?

Yes, the BC849BLT3 delivers a noise figure (NF) of 4.0 dB at I_C = 0.2 mA, V_CE = 5.0 V, R_S = 2.0 kΩ, f = 1.0 kHz, and BW = 200 Hz-making it appropriate for low-noise preamplifier stages in sensor signal chains. Its low C_obo = 4.5 pF and stable h_FE further support high-fidelity analog amplification. For best results, the BC849BLT3 should be biased within its specified low-current region and shielded from digital noise sources.