NXP Semiconductors BC879,112

Overview

BC879,112 from Nexperia (formerly Philips Semiconductors) is an NPN Darlington transistor in a TO-92 (SOT54) through-hole package, delivering high DC current gain (min. 1000 at IC = 150 mA), 80 V V_CES, and 1 A continuous collector current - used in low-speed switching applications such as electromagnetic relay drivers where high input impedance and low base drive are required.

For engineers reviewing the BC879,112 datasheet, BC879,112 pinout, BC879,112 application, or BC879,112 equivalent, key selection criteria include verified V_CES = 80 V, h_FE ≥ 1000 at 150 mA, integrated base-emitter diode/resistor network, TO-92 mechanical compatibility, and thermal resistance R_th(j-a) = 150 K/W on FR4 PCB.

Technical Context

The BC879,112 implements a two-stage monolithic NPN Darlington structure with internal base-emitter shunt resistor and clamp diode, enabling single-resistor base biasing and improved turn-off speed versus standard Darlingtons. It operates with V_BEsat ≤ 2.2 V at IC = 1 A / IB = 1 mA and exhibits f_T = 200 MHz under specified RF conditions.

Its limiting values are defined per IEC 60134: V_CBO = 100 V, V_CES = 80 V, P_tot = 0.83 W at T_amb ≤ 25 °C, and T_j ≤ 150 °C. Switching times are t_on = 500 ns and t_off = 1300 ns under standardized 500 mA load and ±0.5 mA base drive.

Key Specifications

Pinout & Package

BC879,112 is housed in a plastic single-ended leaded (through-hole) TO-92 package (SOT54, SC-43A), with 3 leads spaced on 2.54 mm pitch and overall dimensions of 4.8 × 4.2 × 14.5 mm (D × E × L).

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar Darlington transistor applications.

Compared with BC879,112, BC879,135 offers identical functionality in tape-and-reel format for automated assembly, while BC879-7-F delivers full spec compliance with updated environmental material requirements - both preserve pinout, gain, voltage, and thermal behavior without layout or schematic changes.

Availability

BC879,112 is available at Aetrix Electronics and suitable for industrial relay drivers, low-voltage DC motor control, and power supply enable circuits requiring stable component supply and long-term obsolescence management.

Supply support for BC879,112 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 in high-volume production of essential semiconductors, formed from the former Standard Products division of Philips.

The BC879,112 belongs to Nexperia's legacy bipolar transistor portfolio, designed specifically for cost-sensitive, high-reliability through-hole switching applications in industrial and automotive environments.

FAQ

What is the maximum collector-emitter voltage rating for BC879,112?

The BC879,112 has a maximum collector-emitter sustaining voltage (V_CES) of 80 V under V_BE = 0 V conditions. This rating is validated per IEC 60134 Absolute Maximum Ratings and applies to DC and pulsed operation with proper heatsinking. Exceeding this value risks avalanche breakdown and permanent device failure. The BC879,112 must not be used in circuits where transient or steady-state V_CE exceeds 80 V.

Does BC879,112 include an internal base-emitter resistor?

Yes, the BC879,112 integrates a base-emitter shunt resistor as part of its Darlington structure. This resistor provides automatic bias stabilization and prevents false turn-on due to leakage currents. It eliminates the need for an external pull-down resistor in most relay driver configurations. The resistor value is process-defined and not separately specified, but its presence is confirmed in the original Philips datasheet Figure 1 symbol and "integrated diode and resistor" feature statement.

What is the thermal resistance from junction to ambient for BC879,112?

The BC879,112 has a thermal resistance from junction to ambient (R_th(j-a)) of 150 K/W when mounted on a standard FR4 printed-circuit board, as measured per the datasheet's thermal characterization note. This value assumes no copper pour or heatsink; adding 1 cm² of 1 oz copper on the collector pad reduces R_th(j-a) by ~30 K/W. At 25 °C ambient, the 0.83 W total power dissipation limit corresponds to a maximum junction temperature of 150 °C.

Can BC879,112 replace BC875 in existing designs?

BC879,112 can replace BC875 in most designs, but only if the higher 80 V V_CES (vs. BC875's 45 V) and 100 V V_CBO (vs. BC875's 60 V) do not introduce unintended stress on surrounding components. Both share identical TO-92 package, pinout, and h_FE ≥ 1000 spec. However, BC879,112's higher voltage ratings may affect snubber design or flyback energy handling in inductive loads. Verify all operating voltages before substitution.

What is the typical transition frequency (f_T) of BC879,112?

BC879,112 has a typical transition frequency (f_T) of 200 MHz, measured at V_CE = 5 V, I_C = 0.5 A, and f = 100 MHz. This parameter reflects small-signal AC gain roll-off and does not imply suitability for RF amplification. In switching applications, f_T correlates with achievable edge speeds - consistent with the documented t_on = 500 ns and t_off = 1300 ns values. For digital switching, f_T serves as a secondary indicator of charge storage behavior.