Nexperia USA Inc. BC857B/DG/B4R

Overview

BC857B/DG/B4R from Nexperia is a PNP general-purpose bipolar junction transistor in SOT23 (TO-236AB) package, rated for −45 V V_CEO, −100 mA I_C, and DC current gain (h_FE) of 220–475 at V_CE = −5 V, I_C = −2 mA. It serves as a low-voltage, low-current switching or linear amplification device in compact consumer and industrial PCBs.

For engineers reviewing the BC857B/DG/B4R datasheet, BC857B/DG/B4R pinout, BC857B/DG/B4R application, or BC857B/DG/B4R equivalent, key selection criteria include its PNP polarity, SOT23 footprint compatibility, guaranteed h_FE range, V_CEO derating above 25 °C, and thermal resistance (R_th(j-a) = 500 K/W on FR4).

Technical Context

This transistor operates in active, saturation, and cutoff regions with defined absolute maximum ratings: −45 V V_CEO, −50 V V_CBO, −5 V V_EBO, and 250 mW P_tot at T_amb ≤ 25 °C. Its h_FE variation across temperature (−55 to +150 °C) and collector current (10 µA to 100 mA) is characterized per Figures 6–9.

V_CE(sat) remains ≤ −650 mV at I_C = −100 mA / I_B = −5 mA, and V_BE(sat) ≤ −850 mV under same conditions. Transition frequency f_T is 100 MHz at V_CE = −5 V, I_C = −10 mA, confirming suitability for low-frequency analog and digital switching up to several tens of MHz.

Key Specifications

Pinout & Package

SOT23 (TO-236AB) plastic surface-mounted package with 3 leads; 2.8 mm × 1.4 mm footprint, 1.1 mm height, and standard reflow/wave soldering land patterns per Figures 15–16.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC857B/DG/B4R, BC857B,115 offers identical performance in a different reel format, while MMBT3906LT1G trades 5 V V_CEO headroom for +100 mA I_C capability-making it preferable for heavier loads but requiring redesign if voltage transients exceed −40 V.

Availability

BC857B/DG/B4R is available at Aetrix Electronics and suitable for LED driver circuits, level-shifting interfaces, power rail sequencing, and audio signal amplifiers requiring stable component supply, consistent parametric binning, and long-term SMT manufacturing support.

Supply support for BC857B/DG/B4R 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 semiconductor expert focused on high-volume, high-reliability essential semiconductors for automotive, industrial, mobile, and computing markets.

The BC856/BC857/BC858 series was designed for cost-sensitive, space-constrained general-purpose switching and amplification in consumer and industrial electronics-prioritizing consistent h_FE binning, robust SOT23 thermal performance, and broad voltage/current coverage within a single footprint.

FAQ

Is BC857B/DG/B4R pin-compatible with BC847B?

Yes, BC857B/DG/B4R is pin-compatible with BC847B (its NPN complement) in the SOT23 package, sharing identical pin 1 (base), pin 2 (emitter), and pin 3 (collector) assignments. However, polarity reversal means circuit topology must be adapted-e.g., BC847B sinks current from load to ground, while BC857B sources current from V_CC to load.

What is the maximum ambient temperature for continuous operation at full rated current?

At I_C = −100 mA and P_tot = 250 mW, junction temperature rises by ΔT = P × R_th(j-a) = 125 °C. With T_j(max) = 150 °C, maximum ambient temperature is 25 °C. Derating is required above this-e.g., at 50 °C ambient, max I_C drops to ~65 mA to maintain T_j ≤ 150 °C.

Does BC857B/DG/B4R meet automotive qualification standards?

No. Per Nexperia's Revision History (v.9, July 2022), the BC856/BC857/BC858 series is explicitly marked "non-automotive qualified" and lacks AEC-Q101 stress testing. For automotive use, Nexperia recommends its dedicated −Q qualified variants such as BC857B-Q.

How does the /DG/B4R suffix affect electrical specifications?

The /DG/B4R suffix denotes Nexperia's specific tape-and-reel packaging variant (3,000 pcs/reel, 12 mm tape width, B4R carrier type) and does not alter electrical or thermal specifications. All BC857B devices-regardless of suffix-share identical V_CEO, h_FE, V_CE(sat), and f_T characteristics per the Rev. 9 datasheet.