onsemi BCX70H

Overview

BCX70H from ON Semiconductor is an NPN epitaxial silicon general-purpose transistor in SOT-23 package, rated for 45 V V_CEO, 200 mA I_C, and 350 mW P_C, with DC current gain (h_FE) ranging from 20 to 310 depending on bias condition, commonly used in low-power switching and signal amplification circuits in consumer and industrial electronics.

For engineers reviewing the BCX70H datasheet, pinout, applications, or equivalent options, key selection considerations include its V_CEO/V_CB0 rating, h_FE spread across operating currents, saturation voltage at defined I_C/I_B, noise figure at 1 kHz, and SOT-23 thermal and layout constraints.

Technical Context

The BCX70H operates as a discrete bipolar junction transistor with fixed NPN polarity, optimized for linear amplification and digital switching in low-voltage, low-current applications. Its h_FE varies significantly-20–180 at I_C = 2.0 mA and 70–310 at I_C = 50 mA-indicating strong current-dependent gain behavior.

It exhibits V_CE(sat) ≤ 0.55 V at I_C = 50 mA / I_B = 1.25 mA and f_T = 125 MHz under V_CE = 5 V, I_C = 10 mA, confirming suitability for RF-coupled audio stages and medium-speed digital logic interfacing, but not high-frequency power switching.

Key Specifications

Pinout & Package

SOT-23 surface-mount plastic package with gull-wing leads; compact 2.9 mm × 1.3 mm footprint, 1.0 mm height, and standard JEDEC MO-178 outline. Thermal resistance θ_JA ≈ 357°C/W (typical, no PCB copper).

Key Features

Applications

Equivalent & Alternatives

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

Compared with BCX70H, BC847B offers higher and narrower h_FE range for precision biasing, while MMBT3904 provides broader industry familiarity and tighter typical gain specification-both retain SOT-23 compatibility but differ in gain distribution and qualification history.

Availability

BCX70H is available at Aetrix Electronics and suitable for audio pre-amplifiers, microcontroller interface circuits, low-current LED drivers, and sensor signal coupling applications requiring stable component supply and long-term industrial availability.

Supply support for BCX70H 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

ON Semiconductor is a global semiconductor manufacturer specializing in energy-efficient power, analog, sensor, and connectivity solutions for automotive, industrial, cloud, and IoT applications.

The BCX70H belongs to ON Semiconductor's general-purpose bipolar transistor product line, designed for cost-sensitive, space-constrained applications requiring reliable low-voltage switching and amplification performance.

FAQ

What is the pin configuration of the BCX70H?

The BCX70H uses the standard SOT-23 package with pin 1 as Base, pin 2 as Emitter, and pin 3 as Collector. This pinout is consistent across Fairchild/ON Semiconductor's BCX70 series and matches JEDEC MO-178 mechanical specifications. Layout designers must observe this orientation during PCB routing to avoid functional failure.

Does the BCX70H support switching at 1 MHz?

Yes, the BCX70H supports switching at 1 MHz in saturated or unsaturated modes, given its t_ON = 150 ns and t_OFF = 800 ns values. However, full 1 MHz square-wave operation requires careful attention to base drive strength and load capacitance, as cumulative switching losses may exceed P_C = 350 mW at high duty cycles.

What is the minimum h_FE guaranteed for BCX70H at I_C = 2.0 mA?

The BCX70H guarantees h_FE ≥ 20 at V_CE = 5 V and I_C = 2.0 mA, per its official datasheet. This minimum applies across the full temperature range and lifetime, making it suitable for designs requiring predictable low-current gain, such as standby bias networks or leakage-sensitive amplifiers.

Can BCX70H replace BC847C in existing designs?

BCX70H can functionally replace BC847C in many low-speed switching applications, but h_FE differs significantly: BC847C guarantees 420–800 at I_C = 2 mA, while BCX70H only guarantees 20–180. Designers must verify base drive adequacy and stability margins-especially in linear amplifiers-before substitution.

Is BCX70H qualified for automotive applications?

No, BCX70H is not AEC-Q101 qualified and is intended for commercial and industrial applications only. It lacks automotive-grade screening, extended temperature validation, and failure rate documentation required for automotive ECUs or body control modules. For automotive use, ON Semiconductor recommends AEC-Q101 parts like NSS40201MR6T1G.