NXP Semiconductors BB178,135

Overview

BB178,135 from NXP Semiconductors is a planar technology variable capacitance diode (varactor) in an ultra-small SOD523 (SC-79) surface-mount package, designed for electronic tuning in VHF band B applications up to 460 MHz. It delivers Cd(1V) = 39 pF (typ), Cd(28V) = 2.6 pF (typ), capacitance ratio Cd(1V)/Cd(28V) = 15 (typ), series resistance rs = 0.65 Ω (typ) at 100 MHz, and matching accuracy of ≤2 % via Direct Matching Assembly (DMA).

For engineers reviewing the BB178,135 datasheet, BB178,135 pinout, BB178,135 application, or BB178,135 equivalent, this varactor is selected for high-linearity voltage-controlled oscillators and compact TV tuner designs where tight capacitance matching, low series resistance, and stable VHF performance are critical.

Technical Context

The BB178,135 operates as a reverse-biased junction capacitor whose depletion width-and thus capacitance-varies nonlinearly with applied DC bias voltage. Its planar silicon structure enables precise control of doping profiles to achieve high linearity and repeatable C-V characteristics across 1–28 V.

It is optimized for VHF tuning systems requiring stable capacitance matching across diode pairs or sequences: gliding matching and DMA ensure ≤2 % capacitance deviation over 1–28 V in groups of 10 devices, while its low rs minimizes Q-factor degradation at 100 MHz.

Key Specifications

Pinout & Package

SOD523 (SC-79) plastic surface-mounted package with 2 leads; cathode indicated by marking bar.

Key Features

Applications

Equivalent & Alternatives

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

Compared with BBY52,115 and SMV1232-011, the BB178,135 uniquely balances high C-ratio (15), ultra-low rs (0.65 Ω), and factory DMA matching (≤2 %) specifically for stable VHF Band B tuning - making it the preferred choice where phase noise, image rejection, and production matching consistency are design-critical.

Availability

BB178,135 is available at Aetrix Electronics and suitable for VHF television tuners, voltage-controlled oscillators, FM radio receivers, and RF calibration modules requiring stable component supply and consistent varactor performance across production lots.

Supply support for BB178,135 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 BB178,135 belongs to NXP's RF varactor diode product line, engineered specifically for high-reliability VHF electronic tuning in broadcast and wireless infrastructure where capacitance stability, matching precision, and low-loss operation are essential.

FAQ

What is the primary function of the BB178,135 in RF circuits?

The BB178,135 functions as a voltage-controlled variable capacitance diode (varactor), used to tune resonant frequencies in VHF RF circuits such as television tuners and voltage-controlled oscillators. Its capacitance changes predictably with reverse bias voltage, enabling precise electronic frequency adjustment without mechanical components. The BB178,135 achieves this with a Cd(1V)/Cd(28V) ratio of 15 and low series resistance to maintain high Q-factor performance.

What does the "≤2 % DMA matching" specification mean for BB178,135?

The ≤2 % DMA (Direct Matching Assembly) matching means that when BB178,135 diodes are selected in sequences of 10 units using NXP's gliding matching process, their capacitance values across the 1–28 V range deviate by no more than ±2 % from the group median. This enables reliable use in differential VCO topologies or multi-stage tuners without individual device trimming. The BB178,135 is characterized and sorted to meet this tolerance under standard test conditions.

Can BB178,135 be used in automotive applications?

No - the BB178,135 is not automotive-qualified. Per NXP's legal disclaimers, unless explicitly stated in the datasheet, the device is not tested or warranted for automotive use, including safety-critical or life-support systems. Its specified operating junction temperature range is −55 °C to +125 °C, but qualification per AEC-Q200 or similar standards is not claimed. For automotive designs, engineers must select NXP's formally qualified alternatives and validate BB178,135 independently at their own risk.

What is the maximum reverse voltage rating for BB178,135?

The absolute maximum reverse voltage (VR) for BB178,135 is 32 V, and the peak reverse voltage (VRM) is 35 V when used in series with a 10 kΩ resistor. Exceeding these limits risks permanent junction damage. Designers should maintain bias margins below 32 V - for example, limiting control voltage to ≤28 V - to ensure long-term reliability and avoid accelerated aging. These ratings are defined per IEC 60134 Absolute Maximum Rating System.

How does the SOD523 package of BB178,135 impact PCB layout?

BB178,135's SOD523 (SC-79) package measures 1.25 × 0.85 mm with 0.5 mm lead pitch, enabling dense RF layout in space-constrained tuner modules. Its small footprint minimizes parasitic inductance and stray capacitance, preserving high-frequency performance. Designers must observe recommended pad geometry per NXP's package outline (Fig 4) and ensure solder mask clearance to prevent bridging. The cathode marking bar must align with correct polarity during placement to avoid reverse-bias failure. The BB178,135 is not compatible with larger SOD-323 footprints without rework.