NXP Semiconductors BA278,115

Overview

BA278 from Philips Semiconductors is a planar high-performance band-switching diode in SOD523V surface-mount package, designed for VHF television tuner RF path switching. It delivers max. 35 V reverse voltage, 100 mA forward current, 1.2 pF capacitance at 1 MHz/6 V, 0.7 Ω forward resistance at 100 MHz/2 mA, and operates up to +150 °C junction temperature.

For engineers reviewing the BA278 datasheet, BA278 pinout, BA278 application, or BA278 equivalent, this diode is selected for low-loss RF band selection where minimal signal distortion, tight capacitance control, and stable high-frequency impedance are critical in compact tuner modules.

Technical Context

The BA278 functions as a voltage-controlled RF switch via variable junction capacitance under reverse bias, enabling precise band selection without mechanical relays. Its low 1.2 pF capacitance and sub-1 Ω forward resistance ensure minimal insertion loss and high isolation in VHF front-end circuits.

Designed for operation at 100 MHz with IF = 2 mA, it maintains stable r_D and C_d across −65 °C to +150 °C, supported by thermal resistance R_{th j-s} = 85 K/W - critical for reliability in thermally constrained SMT tuner assemblies.

Key Specifications

Pinout & Package

Package: SOD523V (SC-79), plastic surface-mounted, 2-lead package with cathode marked by bar on top view. Dimensions: D = 1.25 mm, E = 1.15 mm, bp = 0.34 mm, c = 0.26 mm, v = 0.1 mm.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar band-switching diode applications.

Compared with BAV99,125 and BBY52-02W, the BA278 offers optimal balance of ultra-low capacitance, minimal forward resistance, and compact SOD523V packaging - making it preferred for space-limited VHF tuner designs where 1.2 pF C_d and 0.7 Ω r_D directly impact channel selectivity and insertion loss.

Availability

BA278 is available at Aetrix Electronics and suitable for VHF television tuners, surface-mount RF front-end modules, FM radio receivers, and portable VHF communication transceivers requiring stable component supply and long-term obsolescence management.

Supply support for BA278 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

Philips Semiconductors (now NXP Semiconductors) is a global semiconductor innovator founded in the Netherlands, specializing in analog, RF, and discrete power solutions for consumer, automotive, and industrial markets.

The BA278 belongs to Philips' high-frequency discrete diode product line, engineered specifically for low-loss RF band switching in analog and digital broadcast receiver systems operating up to 200 MHz.

FAQ

What is the maximum reverse voltage rating for the BA278?

The BA278 has a maximum continuous reverse voltage (V_R) rating of 35 V, as specified in the Absolute Maximum Ratings table. This value defines the highest DC or peak AC reverse bias the BA278 can withstand without breakdown under normal operating conditions, and must not be exceeded to ensure long-term reliability in VHF tuner applications.

What is the typical diode capacitance of the BA278 and at what test conditions?

The BA278 exhibits a maximum diode capacitance (C_d) of 1.2 pF, measured at 1 MHz with 6 V reverse bias and T_j = 25 °C. This low capacitance is critical for minimizing detuning effects in VHF LC resonant circuits, and the BA278 maintains this value across its qualified operating temperature range.

Does the BA278 have a specified forward voltage, and how is it relevant to circuit design?

Yes - the BA278 has a forward voltage (V_F) of 1 V maximum at I_F = 10 mA and T_j = 25 °C. This parameter helps determine DC bias network power dissipation and ensures sufficient headroom for driving the BA278's anode in band-switching configurations without exceeding total power limits.

Can the BA278 be used in place of a varactor diode for tuning applications?

The BA278 is explicitly designed as a band-switching diode, not a varactor. While its junction capacitance varies with reverse voltage, its C_j vs. V_R curve is optimized for discrete band selection-not continuous tuning. For fine-tuning applications, dedicated varactors like BBY52-02W offer superior C_j linearity and voltage sensitivity over the BA278.

What is the thermal resistance from junction to soldering point for the BA278, and why does it matter?

The BA278 has a thermal resistance from junction to soldering point (R_{th j-s}) of 85 K/W. This value quantifies how effectively heat transfers from the silicon die to the PCB copper pad. In densely packed tuner modules, this parameter guides minimum copper area and thermal via design to keep junction temperature within the −65 °C to +150 °C limit during continuous 100 mA operation.