onsemi BCX70H_D87Z

Overview

BCX70H_D87Z 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. It delivers h_FE = 70–310 at I_C = 50 mA and f_T = 125 MHz, serving as a low-power switching and amplification device in portable audio bias networks and sensor interface stages.

For engineers reviewing the BCX70H_D87Z datasheet, pinout, applications, or equivalent options, key selection criteria include verified V_CEO/V_CBO rating symmetry, SOT-23 terminal assignment (1=Base, 2=Emitter, 3=Collector), h_FE distribution across I_C conditions, and t_ON/t_OFF timing under defined drive conditions.

Technical Context

This transistor operates in active and saturation regions with fixed junction voltage thresholds: V_BE(sat) = 0.6–1.05 V at I_C = 10–50 mA, and V_CE(sat) = 0.35–0.55 V under matched base drive. Its Cob = 4.5 pF at V_CE = 10 V enables stable high-frequency small-signal gain up to 125 MHz.

Noise figure is specified at 6 dB (RS = 2 kΩ, f = 1 kHz, I_C = 0.2 mA), supporting low-noise preamplifier use. Turn-on/turn-off times (150 ns / 800 ns) are measured with defined R_L, R₁, R₂, and V_BB conditions, confirming suitability for digital logic interfacing below 5 MHz.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; 3-terminal configuration optimized for automated placement and thermal relief on 1 oz copper PCBs.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC847B and MMBT3904, BCX70H_D87Z offers the highest combination of V_CEO, I_C, and guaranteed h_FE at 50 mA-making it optimal for medium-power switching where voltage margin and current headroom are critical.

Availability

BCX70H_D87Z is available at Aetrix Electronics and suitable for portable audio bias networks, sensor interface amplifiers, digital logic level translation, and LED driver switches requiring stable component supply and long-term manufacturability.

Supply support for BCX70H_D87Z 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 supplier delivering energy-efficient, intelligent power and sensing solutions for automotive, industrial, cloud, medical, and IoT applications.

The BCX70H_D87Z belongs to ON Semiconductor's general-purpose bipolar transistor product line, designed for cost-sensitive, high-volume applications requiring reliable DC amplification and switching in compact SOT-23 form factor.

FAQ

What is the maximum collector-emitter voltage rating for BCX70H_D87Z?

The BCX70H_D87Z has a maximum collector-emitter voltage (V_CEO) rating of 45 V at T_A = 25°C. This rating applies under open-base conditions and defines the upper limit for safe DC or peak AC voltage swing between collector and emitter terminals. Exceeding this value risks avalanche breakdown and permanent device degradation. Derating is required at elevated ambient temperatures per the datasheet thermal curves.

Does BCX70H_D87Z support switching applications up to 1 MHz?

Yes, BCX70H_D87Z supports switching applications up to approximately 500 kHz reliably. Its t_ON = 150 ns and t_OFF = 800 ns were measured under standardized resistive-load conditions. At 1 MHz, cumulative switching losses and incomplete saturation may occur unless drive strength and layout parasitics are tightly controlled. For >500 kHz use, verify actual waveforms with BCX70H_D87Z in the target circuit.

What is the pin configuration of BCX70H_D87Z in the SOT-23 package?

The BCX70H_D87Z uses standard SOT-23 pinout: Pin 1 is Base, Pin 2 is Emitter, Pin 3 is Collector. This matches JEDEC TO-236AB outline and is consistent across Fairchild/ON Semiconductor documentation. The marking "AH" on the top surface aligns with this orientation. Always confirm physical orientation using optical inspection or continuity testing before PCB assembly.

How does the h_FE of BCX70H_D87Z vary with collector current?

The h_FE of BCX70H_D87Z varies significantly with I_C: minimum 20 at I_C = 10 µA, 180 at I_C = 2.0 mA, and 70 at I_C = 50 mA. This nonlinearity means bias networks must be designed for worst-case h_FE at the intended operating I_C. For BCX70H_D87Z, use h_FE = 70 when designing for 50 mA loads to ensure saturation under all process and temperature extremes.

Is BCX70H_D87Z suitable for low-noise audio preamplifier stages?

Yes, BCX70H_D87Z is suitable for low-noise audio preamplifier stages operating at 1 kHz and below, with a specified noise figure of 6 dB (RS = 2 kΩ). Its V_BE(on) = 0.55–0.75 V and h_FE ≥ 70 support stable emitter-degenerated biasing. However, for wideband or ultralow-noise (<3 dB NF) requirements, dedicated low-noise transistors like BC549C are recommended over BCX70H_D87Z.