NXP Semiconductors BA591,135

Overview

BA591 from NXP Semiconductors is a planar high-performance band-switching diode in the SOD323 (SC-76) surface-mount package, designed for low-loss VHF tuner applications. It delivers 1.05 pF maximum diode capacitance at 1 V reverse bias, 0.7 Ω maximum forward resistance at 10 mA, and supports 35 V continuous reverse voltage and 100 mA forward current.

For engineers reviewing the BA591 datasheet, BA591 pinout, BA591 application, or BA591 equivalent, key selection criteria include RF switching performance at VHF frequencies, low parasitic capacitance and series resistance, AEC-Q101 qualification for automotive tuner modules, and compatibility with compact SMD layouts requiring minimal board area.

Technical Context

The BA591 operates as a voltage-controlled RF switch in band-selection circuits, leveraging its low junction capacitance and forward resistance to minimize insertion loss and maintain signal integrity across VHF bands. Its planar construction and optimized doping profile ensure stable capacitance-voltage characteristics up to 100 MHz.

Designed for use in series or shunt configurations within TV tuner front-ends, the BA591 exhibits 0.45–0.7 Ω typical forward resistance at 3 mA and maintains sub-1 pF capacitance down to 3 V reverse bias - enabling precise impedance matching and harmonic suppression without external tuning components.

Key Specifications

Pinout & Package

The BA591 is housed in the SOD323 (SC-76) plastic surface-mount package: 1.35 mm × 0.85 mm footprint, 0.45 mm height, cathode marked by a bar on the top surface.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BAV99,115 and MMBD7000LT1G, the BA591 uniquely combines AEC-Q101 qualification, sub-1.05 pF capacitance, and SOD323 miniaturization - making it the only option validated for automotive VHF tuner front-ends requiring both size and reliability compliance.

Availability

BA591 is available at Aetrix Electronics and suitable for VHF television tuners, automotive infotainment systems, and surface-mount RF band-switching circuits requiring stable component supply and long-term production continuity.

Supply support for BA591 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

NXP Semiconductors is a global semiconductor company headquartered in Eindhoven, Netherlands, specializing in secure connectivity solutions for automotive, industrial, and consumer applications.

The BA591 belongs to NXP's discrete RF diode product line, engineered specifically for high-frequency band selection in broadcast receiver front-ends where low parasitics and automotive qualification are mandatory.

FAQ

What is the primary function of the BA591 in RF circuits?

The BA591 functions as a high-speed band-switching diode in VHF tuner front-ends, providing low-loss signal path selection via controlled forward/reverse bias. Its 1.05 pF capacitance and 0.7 Ω forward resistance enable minimal insertion loss and high isolation - critical for maintaining signal fidelity in TV and radio receiver designs using the BA591.

Is the BA591 suitable for automotive applications?

Yes, the BA591 is AEC-Q101 qualified, meaning it has passed rigorous stress tests for temperature cycling, humidity, mechanical shock, and lifetime reliability required in automotive environments. This makes the BA591 appropriate for use in vehicle-mounted TV/radio tuner modules where operational stability across –40 °C to +125 °C is essential.

What package type does the BA591 use, and how is polarity identified?

The BA591 uses the SOD323 (SC-76) surface-mount plastic package, measuring 1.35 mm × 0.85 mm. Polarity is indicated by a marking bar on the top surface, which identifies Pin 1 as the cathode - consistent with the simplified outline in the official BA591 datasheet and verified on actual device markings.

What are the absolute maximum ratings for reverse voltage and forward current in the BA591?

The BA591 has an absolute maximum continuous reverse voltage (VR) of 35 V and a continuous forward current (IF) rating of 100 mA. These values define safe operating limits under steady-state conditions; exceeding them risks permanent degradation. Designers must observe these limits when implementing the BA591 in tuner bias networks or RF switching nodes.

How does the BA591 compare to general-purpose switching diodes like the 1N4148 in VHF applications?

Unlike the 1N4148 - which exhibits ~4 pF capacitance and ~1.5 Ω forward resistance - the BA591 offers 1.05 pF max capacitance and 0.7 Ω max rD, making it specifically optimized for VHF band-switching where parasitic reactance directly impacts filter tuning and insertion loss. The BA591's SOD323 footprint and AEC-Q101 qualification further distinguish it from generic diodes.