onsemi BCX19_D87Z

Overview

BCX19_D87Z from ON Semiconductor is an NPN medium-power bipolar junction transistor (BJT) designed for general-purpose amplification and switching in low-to-medium current analog and digital circuits, with V_CEO = 45 V, I_C = 500 mA continuous, h_FE = 100–600 at I_C = 100 mA, V_CE(sat) = 0.62 V at I_C = 500 mA / I_B = 50 mA, and SOT-23 package. It is commonly used in signal amplification stages of consumer audio preamps and LED driver bias networks.

For engineers reviewing the BCX19_D87Z datasheet, pinout, applications, or equivalent options, key selection considerations include DC current gain linearity across I_C = 100–500 mA, thermal resistance (R_θJA = 417 °C/W), safe operating area limits, and SOT-23 footprint compatibility in space-constrained PCB layouts.

Technical Context

This device operates as a single NPN silicon BJT fabricated on Fairchild's Process 38, optimized for stable h_FE performance over temperature and collector current. Its breakdown ratings-V_CEO = 45 V, V_CBO = 50 V, and V_EBO = 5.0 V-define its safe voltage handling in common-emitter configurations with resistive or inductive loads.

The BCX19_D87Z exhibits defined saturation behavior (V_CE(sat) ≤ 0.62 V) and turn-on threshold (V_BE(on) = 1.2 V at I_C = 500 mA), enabling predictable base drive design in linear amplifiers and saturated-switch applications where power dissipation must remain within PD = 300 mW at T_A = 25°C.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; compact 2.90 mm × 1.30 mm footprint, 1.0 mm height, and standard JEDEC MO-178 outline. Marking "U1" identifies the BCX19_D87Z variant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN medium-power transistor applications.

Compared with BCX19_D87Z, BC817-40 offers higher guaranteed h_FE for reduced base drive, while MMBT2222A trades voltage rating for broader availability and lower cost in sub-40 V designs-neither is pin-compatible without validation of layout clearance and thermal margin.

Availability

BCX19_D87Z is available at Aetrix Electronics and suitable for audio pre-amplifier stages, LED constant-current bias networks, DC motor speed control (low-power), and logic-level signal inverter circuits requiring stable component supply and consistent parametric performance across manufacturing lots.

Supply support for BCX19_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 manufacturer specializing in energy-efficient power management, analog, sensor, and logic devices for automotive, industrial, cloud computing, and consumer applications.

The BCX19_D87Z belongs to ON Semiconductor's legacy general-purpose BJT product line, originally developed by Fairchild and maintained for cost-sensitive, high-volume discrete amplifier and switching applications where proven reliability and SOT-23 compatibility are essential.

FAQ

What is the maximum collector-emitter voltage rating for BCX19_D87Z?

The BCX19_D87Z has a maximum collector-emitter voltage (V_CEO) rating of 45 V at T_C = 25°C. This rating applies under open-base conditions and defines the absolute upper limit for voltage across the collector and emitter terminals before breakdown occurs. Exceeding this value risks irreversible device failure. The BCX19_D87Z must be operated within this limit in all circuit configurations, including inductive load switching where voltage spikes may occur.

Does BCX19_D87Z have a specified thermal resistance value?

Yes, the BCX19_D87Z has a specified junction-to-ambient thermal resistance (R_θJA) of 417 °C/W under standard SOT-23 mounting conditions on FR-4 PCB with no copper pour. This value is used to calculate expected junction temperature rise (ΔT_J = P_D × R_θJA) for a given power dissipation. The BCX19_D87Z must be thermally managed accordingly-especially above 100 mW-to avoid exceeding its maximum junction temperature of +150°C.

What is the DC current gain (h_FE) range for BCX19_D87Z at 100 mA collector current?

The BCX19_D87Z exhibits a DC current gain (h_FE) ranging from 100 to 600 when tested at I_C = 100 mA and V_CE = 1.0 V. This wide spread reflects process variation and requires circuit design to accommodate minimum and maximum extremes-e.g., using emitter degeneration or base bias networks that remain functional across the full h_FE range. The BCX19_D87Z datasheet confirms this range as guaranteed for production units.

Can BCX19_D87Z be used in switching applications?

Yes, the BCX19_D87Z is suitable for low-frequency switching applications such as LED drivers and relay coils, with verified V_CE(sat) ≤ 0.62 V at I_C = 500 mA / I_B = 50 mA. Its SOT-23 package and defined saturation characteristics enable predictable turn-on behavior. However, the BCX19_D87Z is not characterized for switching speed (t_on/t_off), so it should not be used in high-frequency (>1 MHz) PWM or RF switching without empirical validation.

What is the package type and pin configuration of BCX19_D87Z?

The BCX19_D87Z uses the SOT-23 surface-mount package with three gull-wing leads. Pin 1 is Base, Pin 2 is Emitter, and Pin 3 is Collector-standardized per JEDEC MO-178. The top marking "U1" identifies the BCX19_D87Z variant. This pinout is fixed and non-reversible; incorrect PCB layout will result in functional failure. The BCX19_D87Z must be placed with correct orientation to match this assignment.