NXP Semiconductors BBY31,215

Overview

BBY31,215 from NXP Semiconductors (formerly Philips) is a UHF variable capacitance diode fabricated in planar technology and housed in an SOT23 surface-mount package. It delivers 16.5 pF capacitance at 1 V reverse bias, 1.9 pF at 28 V, with an 8.3:1 capacitance ratio and ≤1.2 Ω series resistance at 470 MHz - optimized for electronic tuning in UHF TV tuners and voltage-controlled oscillators.

For engineers reviewing the BBY31,215 datasheet, BBY31,215 pinout, BBY31,215 application, or BBY31,215 equivalent, key selection criteria include reverse voltage range (up to 30 V), junction temperature limits (−55 °C to +125 °C), low leakage (≤10 nA at 28 V, 25 °C), and verified SOT23 pin configuration with terminal 1 as anode, terminal 2 as no-connect, and terminal 3 as cathode.

Technical Context

The BBY31,215 operates as a voltage-dependent capacitor where junction depletion width-and thus capacitance-varies nonlinearly with applied reverse bias. Its planar construction ensures stable C-V characteristics across UHF frequencies up to 470 MHz, with measured series resistance ≤1.2 Ω confirming low RF loss in oscillator tank circuits.

Capacitance tuning follows a predictable inverse-square-root relationship with reverse voltage, validated by typical C-V curves at 1 MHz (Fig.2) and temperature coefficient data (Fig.4). The device exhibits minimal drift over −55 °C to +125 °C operating junction temperature, supporting stable VCO performance in ambient-varying environments.

Key Specifications

Pinout & Package

Package: SOT23 - 3-terminal plastic surface-mount package with 1.3 mm × 2.9 mm footprint, 1.1 mm height, and gull-wing leads for reflow compatibility.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar varactor diode applications.

Compared with BBY31,215, BBY40,215 offers greater low-voltage capacitance but narrower tuning ratio, while SMV1232–079LF provides superior high-frequency performance and lower series resistance at the cost of non-SOT23 packaging and revised thermal management requirements.

Availability

BBY31,215 is available at Aetrix Electronics and suitable for UHF television tuners, voltage-controlled oscillators, FM radio front-ends, and RF filter tuning modules requiring stable component supply and long-term obsolescence support.

Supply support for BBY31,215 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 BBY31,215 belongs to NXP's legacy RF discrete portfolio, originally developed by Philips for high-linearity UHF tuning applications where predictable C-V behavior and SMT reliability were critical in mass-produced broadcast equipment.

FAQ

What is the maximum reverse voltage rating for BBY31,215?

The BBY31,215 has a maximum continuous reverse voltage (VR) rating of 30 V, as specified in the Absolute Maximum Ratings table. This limit ensures reliable junction integrity under sustained bias conditions. Exceeding 30 V may cause irreversible breakdown. The device is typically operated between 1 V and 28 V to maintain its specified capacitance range (16.5 pF to 1.9 pF), and BBY31,215 must never be forward-biased during normal tuning operation.

How is the SOT23 pinout configured for BBY31,215?

The BBY31,215 uses standard SOT23 pinout: Terminal 1 is the anode, Terminal 2 is internally not connected (must remain unattached on PCB), and Terminal 3 is the cathode. This configuration is confirmed in Figure 1 of the original Philips datasheet (M3D088, 1996). Correct orientation is essential - BBY31,215 will not function if Terminal 2 is mistakenly grounded or routed, and reverse polarity damages the junction.

What does the capacitance ratio of 8.3 mean for BBY31,215 in practical design?

The 8.3 capacitance ratio (Cd@1V / Cd@28V = 16.5 pF / 1.9 pF) defines BBY31,215's usable tuning bandwidth in resonant circuits. In practice, this enables approximately a 2.85:1 frequency ratio (since f ∝ 1/√C) - sufficient for full UHF TV band coverage (470–862 MHz) with one varactor. Designers use this ratio to size tank inductors and set bias voltage ranges without adding switching diodes or multiple varactors.

Is BBY31,215 suitable for operation above 1 GHz?

No - BBY31,215 is characterized up to 470 MHz for series resistance (rs ≤ 1.2 Ω) and its C-V data is specified at 1 MHz. While functional as a varactor beyond 500 MHz, parasitic inductance and rising rs degrade Q-factor and tuning linearity. For 1–2.4 GHz applications, NXP recommends alternatives like the SMV1232–079LF. BBY31,215 remains optimal for UHF (0.47–0.86 GHz) and VHF systems where its proven C-V stability and SOT23 integration are decisive.

What is the thermal operating range of BBY31,215?

The BBY31,215 supports an operating junction temperature range of −55 °C to +125 °C, with storage temperature spanning the same interval. This allows deployment in consumer TV enclosures (where internal temperatures may exceed 70 °C) and industrial RF modules exposed to wide ambient swings. Thermal derating is not required within these limits, and BBY31,215 maintains specified C-V characteristics across the full range per graphical data (Fig.4).