Infineon Technologies BC818K-25

Overview

BC818K-25 from Nexperia is an NPN silicon general-purpose audio-frequency transistor in SOT23 package, rated for 25 V V_CEO, 500 mA I_C, and 500 mW P_tot at T_S ≤ 115 °C, with h_FE = 160–250 (IC = 100 mA, V_CE = 1 V), V_CE(sat) ≤ 0.7 V (IC = 500 mA, IB = 50 mA), and f_T = 170 MHz - used in low-voltage switching and linear amplification stages of power management and signal conditioning circuits.

For engineers reviewing the BC818K-25 datasheet, BC818K-25 pinout, BC818K-25 application, or BC818K-25 equivalent, key selection criteria include its AEC-Q101 qualification, shrink-chip thermal performance (R_thJS ≤ 70 K/W), group-25 current gain binning, and complementary PNP pairing with BC808K-25W for push-pull output stages.

Technical Context

This device operates as a medium-current, medium-voltage NPN bipolar junction transistor optimized for stable DC amplification and fast-switching duty in ambient temperatures up to 150 °C junction temperature. Its design emphasizes low saturation voltage and high h_FE consistency across the 100–500 mA operating range, supported by thermal derating curves specific to the SOT23-3 package variant designated "K".

The BC818K-25 belongs to the BC817/BC818 family differentiated by collector-emitter breakdown voltage (25 V vs. 45 V for BC817 variants) and thermal resistance profile. It shares identical pinout and marking logic with BC817K-25 but is electrically binned for lower V_CEO and higher h_FE minimum at 300 mA test condition (h_FE ≥ 100).

Key Specifications

Pinout & Package

BC818K-25 is housed in a RoHS-compliant SOT23-3 plastic surface-mount package with gull-wing leads and standardized JEDEC MO-203AA outline. The package supports reflow soldering per IPC-J-STD-020 and provides mechanical robustness for automotive-grade board assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BC818-25, BC818K-25 delivers 52% higher power handling and AEC-Q101 compliance; versus BC808K-25W, it provides complementary polarity and identical thermal architecture but cannot substitute in NPN-only roles.

Availability

BC818K-25 is available at Aetrix Electronics and suitable for automotive lighting control, industrial sensor signal conditioning, and low-voltage power management requiring stable component supply and long-term lifecycle support.

Supply support for BC818K-25 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 essential efficiency-enhancing components, delivering high-volume, high-reliability discrete and logic devices for automotive, industrial, and consumer markets.

The BC817/BC818 family was engineered for cost-sensitive, high-yield general-purpose analog switching and amplification - emphasizing AEC-Q101 readiness, tight h_FE binning, and thermal resilience in compact SOT packages.

FAQ

What is the maximum allowable junction temperature for BC818K-25?

The absolute maximum junction temperature (T_j) is 150 °C, as specified in the Absolute Maximum Ratings table. Operation above this value risks permanent degradation of h_FE and increased leakage. Thermal design must ensure that power dissipation and ambient conditions keep actual T_j below this limit, using the provided R_thJS ≤ 70 K/W and P_tot derating curve.

Is BC818K-25 pin-compatible with BC817K-25?

Yes - both share identical SOT23-3 package, pin 1 = Emitter, pin 2 = Base, pin 3 = Collector, and identical marking layout. However, BC817K-25 has V_CEO = 45 V and V_CBO = 50 V, while BC818K-25 is rated for 25 V and 30 V respectively; substituting without verifying voltage margins may cause premature failure.

Does BC818K-25 require external base resistors in switching applications?

Yes - the base terminal is not internally limited. For reliable saturation at I_C = 500 mA, a base current of ≥50 mA is required, meaning a series resistor of ≤100 Ω is needed from a 5 V logic source. Omitting this resistor risks excessive base current, thermal runaway, and device destruction during turn-on transients.

Can BC818K-25 be used in linear regulator pass transistor applications?

Yes - its guaranteed h_FE ≥ 160 at 100 mA and low V_CE(sat) support stable current gain in series-pass configurations. However, thermal design is critical: at 1 A output with 3 V dropout, dissipation exceeds 3 W, requiring external heatsinking - the device itself is rated for ≤500 mW without auxiliary cooling.