onsemi BCX71J_D87Z

Overview

BCX71J_D87Z from ON Semiconductor is an NPN general-purpose bipolar junction transistor (BJT) in SOT-23 package, rated for V_CEO = 45 V, I_C = 100 mA, and h_FE = 250–630 at I_C = 2 mA, used in low-power switching and amplification circuits such as LED drivers and signal buffering in portable instrumentation.

For engineers reviewing the BCX71J_D87Z datasheet, pinout, applications, or equivalent options, key selection criteria include DC current gain linearity at low collector current, thermal resistance in SOT-23, saturation voltage under 10 mA drive, and compatibility with 3.3 V logic-level base control in space-constrained PCB layouts.

Technical Context

The BCX71J_D87Z operates as a discrete NPN switch or small-signal amplifier with fixed-emitter bias configuration. Its h_FE range (250–630) is specified at I_C = 2 mA and V_CE = 5 V, and it achieves V_CE(sat) ≤ 0.38 V at I_C = 10 mA and I_B = 0.5 mA.

Thermal performance is defined by R_θJA = 300 °C/W (on FR-4, 1 cm² copper pad), and maximum power dissipation is limited to 250 mW at T_A = 25 °C. Device behavior follows standard BJT Ebers-Moll modeling without integrated protection diodes or built-in resistors.

Key Specifications

Pinout & Package

SOT-23 plastic surface-mount package with gull-wing leads; 3-terminal configuration optimized for automated placement and reflow soldering on high-density PCBs.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar NPN switching applications.

Compared with BCX71J_D87Z, BC847BJ,115 offers tighter h_FE control but reduced maximum gain, while MMBT3904LT1G trades 5 V headroom and lower low-current gain for broader industry availability and lower cost in high-volume consumer designs.

Availability

BCX71J_D87Z is available at Aetrix Electronics and suitable for LED driver circuits, signal level shifting, low-power amplifier stages, and relay driver interfaces requiring stable component supply across industrial, instrumentation, and portable electronics programs.

Supply support for BCX71J_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 focused on energy-efficient electronics, delivering discrete, analog, and power management solutions for automotive, industrial, and cloud infrastructure markets.

The BCX71J_D87Z belongs to ON Semiconductor's BCX71 family of general-purpose NPN transistors, designed specifically for cost-sensitive, space-constrained low-voltage switching and amplification in consumer and industrial edge devices.

FAQ

What is the maximum collector-emitter voltage rating for BCX71J_D87Z?

The BCX71J_D87Z has a maximum collector-emitter voltage (V_CEO) rating of 45 V. This specification defines the highest voltage that can be applied between collector and emitter with the base open before breakdown occurs. Exceeding this value risks permanent damage. The BCX71J_D87Z is therefore suited for 24 V and lower DC systems, including industrial control I/O and battery-powered instrumentation where transient suppression is externally managed.

Does BCX71J_D87Z have built-in base-emitter resistors?

No, the BCX71J_D87Z is a bare NPN bipolar junction transistor with no integrated resistors. It requires external base current limiting and biasing components. Unlike digital transistors (e.g., NSVD series), the BCX71J_D87Z provides full design flexibility for custom gain, speed, and saturation control-but demands careful calculation of base resistor values based on target I_C, h_FE, and drive voltage. This applies to all BCX71J_D87Z units.

What is the h_FE range for BCX71J_D87Z and how is it binned?

The BCX71J_D87Z is binned to an h_FE range of 250–630 at I_C = 2 mA and V_CE = 5 V. The "J" suffix in the part number explicitly denotes this gain bin. This wide but guaranteed range allows designers to select base resistors conservatively for worst-case conduction while retaining margin for low-power operation. Each BCX71J_D87Z unit meets this specification as tested during final wafer sort.

Can BCX71J_D87Z replace BCX71K_D87Z in the same PCB layout?

No, BCX71J_D87Z and BCX71K_D87Z are not interchangeable without validation. While both share the SOT-23 package and NPN topology, the "K" suffix indicates a different h_FE bin (420–800). Substituting BCX71J_D87Z for BCX71K_D87Z may result in insufficient base drive in high-gain-dependent circuits, leading to incomplete saturation or slower switching. Always verify bias network compatibility before cross-bin substitution of BCX71J_D87Z.

What is the thermal resistance (R_θJA) of BCX71J_D87Z and how does it affect PCB layout?

The BCX71J_D87Z has a junction-to-ambient thermal resistance (R_θJA) of 300 °C/W on standard FR-4 with a 1 cm² copper pad. This means each watt dissipated raises the junction temperature by 300 °C above ambient. To maintain reliability, keep power dissipation below 100 mW in still-air environments or add thermal relief pads and stitching vias. Layout decisions directly impact BCX71J_D87Z performance-undersized copper reduces effective R_θJA margin.