NXP Semiconductors BC857BT,115

Overview

BC857BT,115 from Nexperia is a PNP general purpose transistor in SC-75 (SOT416) package, rated for −45 V V_CEO, −100 mA I_C, and 150 mW P_tot, with h_FE of 220–475 at −2 mA I_C. It serves as a low-power switching and amplification device in portable battery-powered circuits.

For engineers reviewing the BC857BT,115 datasheet, BC857BT,115 pinout, BC857BT,115 application, or BC857BT,115 equivalent, key selection criteria include its PNP polarity, SC-75 footprint compatibility, −45 V breakdown rating, DC current gain range, and thermal resistance of 833 K/W in free air.

Technical Context

This discrete PNP bipolar junction transistor operates in active, saturation, and cutoff regions for linear amplification and digital switching. Its design supports low-voltage, low-current signal control with guaranteed h_FE ≥220 at −2 mA I_C and V_CE = −5 V.

Thermal performance is defined for FR4 PCB mounting: R_{th j-a} = 833 K/W, T_j max = 150 °C, and ambient operating range from −65 °C to +150 °C. Saturation behavior is characterized at I_C/I_B = 20, with V_CEsat ≤ −400 mV at −100 mA I_C.

Key Specifications

Pinout & Package

BC857BT,115 is housed in a plastic surface-mounted SC-75 (SOT416) package measuring 1.75 mm × 1.45 mm × 0.95 mm with 3 leads. The package is optimized for high-density PCB layouts and automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC857B,215, BC857BT,115 offers identical electrical performance in a smaller SC-75 package ideal for ultra-compact designs, while MMBT3906LT1G trades gain consistency and size for improved thermal handling in SOT-23 - making BC857BT,115 optimal for space-constrained, low-leakage, high-gain PNP switching.

Availability

BC857BT,115 is available at Aetrix Electronics and suitable for portable power switching, level-shifting interfaces, audio signal amplification, and low-power sensor biasing requiring stable component supply and consistent parametric performance across production lots.

Supply support for BC857BT,115 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

Nexperia is a global leader in discrete, logic, and PowerMOS semiconductors, serving automotive, industrial, computing, consumer, and wearable markets with high-volume, high-reliability components.

The BC857BT,115 belongs to Nexperia's BC856T/BC857T series of PNP general purpose transistors, designed specifically for low-voltage, low-current switching and amplification in space-constrained portable electronics.

FAQ

What is the maximum collector-emitter voltage rating for BC857BT,115?

The BC857BT,115 has a maximum collector-emitter voltage (V_CEO) rating of −45 V under open-base conditions. This specification defines the upper limit of reverse bias the transistor can withstand between collector and emitter without breakdown, making it suitable for 3.3 V and 5 V system rails with safety margin. Exceeding this value risks permanent damage to the BC857BT,115 junction structure.

What is the DC current gain range of BC857BT,115 at typical operating conditions?

The BC857BT,115 exhibits a DC current gain (h_FE) range of 220 to 475 when measured at V_CE = −5 V and I_C = −2 mA. This gain window is guaranteed across production lots and enables robust base resistor calculation for switching applications. The BC857BT,115 achieves higher minimum h_FE than BC857AT or BC857CT variants, optimizing it for designs requiring consistent low-drive operation.

Does BC857BT,115 have a specified thermal resistance, and how does it impact PCB layout?

Yes, BC857BT,115 has a thermal resistance from junction to ambient (R_{th j-a}) of 833 K/W when mounted on an FR4 PCB in free air. This relatively high value means even modest power dissipation (e.g., 50 mW) causes significant junction temperature rise - so PCB layout must avoid excessive copper isolation around the SC-75 pad. The BC857BT,115 benefits from minimal thermal relief and adjacent ground pour to improve heat spreading without violating SOT416 mechanical constraints.

Can BC857BT,115 be used as a direct replacement for BC857B,215 in existing designs?

Yes, BC857BT,115 is electrically and physically identical to BC857B,215 - same SC-75 package, identical pinout, and matching electrical specifications including V_CEO, h_FE, and V_CEsat. The only difference is packaging format: BC857BT,115 ships in 3,000-piece reels while BC857B,215 uses 10,000-piece reels. No schematic or layout changes are needed when substituting BC857BT,115 into a design originally specifying BC857B,215.

What is the base-emitter saturation voltage of BC857BT,115 under full-load switching conditions?

Under full-load switching conditions (I_C = −100 mA, I_B = −5 mA, I_C/I_B = 20), the BC857BT,115 has a maximum base-emitter saturation voltage (V_BEsat) of −770 mV. This value ensures sufficient forward bias to maintain deep saturation while allowing accurate prediction of base drive requirements. Designers must account for this V_BEsat when calculating base resistor values to guarantee reliable turn-on of the BC857BT,115 across temperature and process variation.