Diodes Incorporated BC857BFZ-7B

Overview

BC857BFZ-7B from Diodes Incorporated is a 45V PNP small-signal transistor in a 0.36 mm² DFN0606 package, rated for −100 mA continuous collector current and 925 mW power dissipation at 2 oz copper heatsinking. It delivers h_FE = 200–470 at −2 mA to −100 mA, V_CE(sat) = −70 mV (typ.) at −10 mA/−0.5 mA drive, and f_T = 100–270 MHz, enabling high-speed switching in compact power management and signal routing circuits.

For engineers reviewing the BC857BFZ-7B datasheet, BC857BFZ-7B pinout, BC857BFZ-7B application, or BC857BFZ-7B equivalent, key selection criteria include its −45 V V_CEO, low-profile 0.4 mm height, NiPdAu terminal finish, JESD22-A114 HBM ESD rating of 4 kV, and complementary pairing with BC847BFZ for push-pull designs.

Technical Context

This PNP transistor operates in active, saturation, and cutoff regions with verified DC current gain spanning 200–470 across −10 µA to −100 mA collector currents. Its thermal resistance is 135 °C/W junction-to-lead when the exposed collector pad is soldered to 25 mm × 25 mm 2 oz copper, supporting stable operation up to +150 °C junction temperature.

The device uses a monolithic silicon die in X2-DFN0606-3 packaging with three terminals-collector, base, emitter-arranged in top-view order C-E-B, where the bar denotes the base-emitter side. Its 2.0 pF output capacitance and 270 MHz f_T support RF-coupled biasing and medium-frequency switching up to ~100 MHz.

Key Specifications

Pinout & Package

Package: X2-DFN0606-3 - 0.62 mm × 0.62 mm body, 0.4 mm max height, molded green compound (UL 94V-0), exposed collector pad on bottom surface.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar PNP small-signal transistor applications.

Compared with BC857B,115, BC857BFZ-7B saves 83% board area and improves thermal resistance by 54%; versus DMG1012T, it trades 100 mA extra current for 25 V higher breakdown, making it optimal for general-purpose biasing and interface roles requiring voltage margin.

Availability

BC857BFZ-7B is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, load switch control, and audio signal inversion requiring stable component supply, consistent parametric performance, and RoHS-compliant green manufacturing.

Supply support for BC857BFZ-7B 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability, energy-efficient components for consumer, industrial, and automotive markets.

The BC857BFZ belongs to Diodes' X2-DFN series of ultra-miniature transistors, designed specifically for space-constrained portable electronics and high-density power management subsystems where thermal efficiency and environmental compliance are mandatory.

FAQ

What is the recommended PCB pad layout for BC857BFZ-7B?

The official AP02001 layout specifies a 0.62 mm × 0.62 mm thermal pad with 0.15 mm solder mask opening, surrounded by 0.25 mm × 0.25 mm stencil apertures for the three top-side terminals. The collector pad must be fully connected to internal ground or power planes via ≥4 thermal vias (0.3 mm diameter, 0.8 mm pitch) to achieve R_θJL = 135 °C/W.

Can BC857BFZ-7B replace BC857C in existing designs?

Yes, but only if h_FE tolerance is acceptable: BC857BFZ-7B has h_FE = 200–470 (−2 mA), while BC857C is 420–800. Base drive circuitry may require verification - a design using minimum h_FE = 420 could underdrive this part at low current, risking incomplete saturation.

Is the exposed collector pad electrically connected to the collector terminal?

Yes - the bottom-side exposed pad is an integral part of the collector metallization. It must be soldered to a PCB copper area designated as collector potential; floating or grounding the pad will cause catastrophic failure due to internal shorting and thermal runaway.

Does BC857BFZ-7B support reflow soldering per J-STD-020?

Yes - it is rated Moisture Sensitivity Level 1 (MSL-1), meaning it can be stored indefinitely at ≤30 °C/60% RH and subjected to standard Pb-free reflow profiles (peak 260 °C, 20–40 sec above 217 °C) without baking or special handling.