NXP Semiconductors BB173X

Overview

BB173X from NXP Semiconductors is a VHF variable capacitance diode (varactor) fabricated in planar technology and housed in an SOD523 (SC-79) ultra-small SMD package. It delivers Cd(1V) = 34.65–42.35 pF, Cd(28V) = 2.361–2.754 pF, and a Cd(1V)/Cd(28V) ratio of 13.5–15, enabling precise frequency tuning in compact RF front-ends.

For engineers reviewing the BB173X datasheet, BB173X pinout, BB173X application, or BB173X equivalent, this page provides verified capacitance curves, reverse voltage limits (32 V), series resistance (0.65–0.8 Ω at 100 MHz), junction temperature range (−55 °C to +125 °C), and SOD523 package mechanical data - all critical for VCO design and impedance matching in portable wireless systems.

Technical Context

The BB173X operates as a reverse-biased junction capacitor whose depletion width-and thus capacitance-varies nonlinearly with applied DC bias. Its planar construction ensures stable C-V characteristics across −55 °C to +125 °C, with typical TCCd ranging from −100 ppm/K to −300 ppm/K depending on VR.

Designed specifically for VHF band tuning (30–300 MHz), it exhibits low series resistance (rs ≤ 0.8 Ω) and minimal reverse leakage (IR ≤ 10 nA at VR = 30 V, 25 °C), supporting high-Q resonant circuits and minimizing phase noise in oscillator topologies.

Key Specifications

Pinout & Package

SOD523 (SC-79) ultra-small surface-mount plastic package: 1.25 × 0.85 × 0.65 mm body, 0.17 mm lead pitch, cathode marked by bar.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BBY52-02W and MV2103, the BB173X offers the highest Cd(1V)/Cd(28V) ratio (15) and lowest series resistance (0.65 Ω) in the SOD523 footprint, making it optimal for wide-range, low-phase-noise VHF VCOs where board area and spectral purity are constrained.

Availability

BB173X is available at Aetrix Electronics and suitable for VHF radio tuners, portable transceivers, ISM-band IoT transmitters, and test equipment synthesizers requiring stable component supply and tight parametric consistency across production lots.

Supply support for BB173X 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 BB173X belongs to NXP's RF discrete portfolio, engineered specifically for high-linearity, low-loss voltage-controlled tuning in VHF communication systems - emphasizing miniaturization, thermal stability, and repeatable C-V behavior.

FAQ

What is the maximum reverse voltage rating for BB173X?

The BB173X has an absolute maximum reverse voltage (VR) rating of 32 V per IEC 60134. Exceeding this value risks permanent junction breakdown. For reliable long-term operation, design bias networks to stay below 28 V DC, aligning with the datasheet's Cd(28V) characterization point and providing 4 V safety margin.

Does BB173X have a specified capacitance temperature coefficient?

Yes - the BB173X exhibits a negative capacitance temperature coefficient (TCCd), typically ranging from −100 ppm/K to −300 ppm/K depending on reverse voltage, as shown in Figure 3 of the official datasheet. This behavior must be compensated in precision VCO designs via bias voltage trimming or complementary capacitor networks.

Is BB173X suitable for automotive applications?

No - the BB173X is not automotive-qualified. NXP explicitly states in Section 10.3 of the datasheet that non-automotive qualified products like BB173X are neither tested nor warranted for use in safety-critical or life-support systems. Its guaranteed Tj range (−55 °C to +125 °C) supports industrial use but does not meet AEC-Q200 stress requirements.

How is the cathode identified on BB173X?

The cathode of the BB173X is marked by a visible bar on the device body, consistent with standard SOD523 orientation. Pin 1 (cathode) is located adjacent to the marking bar; Pin 2 (anode) is the opposite terminal. This polarity must be observed to ensure correct reverse-bias operation and avoid forward conduction.

What is the typical series resistance of BB173X at 100 MHz?

The BB173X has a typical series resistance (rs) of 0.65 Ω measured at 100 MHz with Cd = 30 pF, as specified in Table 5 of the NXP datasheet. This low rs value directly contributes to high-quality factor (Q) in resonant circuits, supporting phase noise performance better than varactors with rs > 1 Ω in the same frequency band.