Diodes Incorporated ZC831ATC

Overview

ZC831ATC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 15.0 pF nominal capacitance at 2 V, 4.5–6.0 capacitance ratio (C₂/C₂₀), ≥300 Q at 50 MHz, and ultra-low reverse leakage (200 pA typ.), enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure and mobile radio front-ends.

For engineers reviewing the ZC831ATC datasheet, ZC831ATC pinout, ZC831ATC application, or ZC831ATC equivalent, key selection criteria include its hyperabrupt CV slope (300–400 ppm/°C tempco), SOT23 package compatibility with high-density RF layouts, and verified performance under 25 V reverse bias with <20 nA leakage at 20 V.

Technical Context

The ZC831ATC employs a silicon hyperabrupt junction profile to achieve steep, linearized C–V response-critical for stable frequency pulling in VCXOs where tuning linearity directly impacts loop stability and phase noise floor. Its 25 V breakdown rating and 200 pA typical IR support clean biasing in low-current PLL control paths.

Designed for 1–50 MHz RF tuning applications, it operates across –55°C to +150°C with tight capacitance tolerance (±10% for 'A' grade) and controlled temperature coefficient (300–400 ppm/°C), ensuring predictable drift compensation in temperature-compensated oscillator topologies.

Key Specifications

Pinout & Package

Supplied in SOT23 surface-mount package (JEDEC TO-236AB), with cathode marked by a single bar on lead 3. Thermal pad not present; power dissipation rated at 330 mW at 25°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMV1232-011LF and BBY52-02W, ZC831ATC offers balanced trade-offs: sufficient C₂/C₂₀ for wide-pull VCXOs, 25 V breakdown for flexible bias design, and SOT23 compatibility with legacy RF layout footprints-making it optimal for cost-sensitive, high-volume wireless timing modules.

Availability

ZC831ATC is available at Aetrix Electronics and suitable for VCXO frequency control, TCXO temperature compensation, and wireless transceiver filter tuning requiring stable component supply across extended temperature ranges and high-reliability RF environments.

Supply support for ZC831ATC 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

Zetex Semiconductors plc was a UK-based ISO 9001 and TS16949-certified manufacturer specializing in high-performance analog and RF semiconductors before its acquisition by Diodes Incorporated in 2008.

The 830 series varactors were engineered specifically for precision frequency control in communication oscillators-emphasizing hyperabrupt CV linearity, low leakage, and high Q to meet stringent phase noise and stability requirements in wireless infrastructure.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The ZC831ATC has an absolute maximum reverse voltage rating of 25 V, but for reliable long-term operation with margin, Zetex specifies 20 V as the maximum continuous reverse bias. Operating above 20 V increases risk of accelerated leakage growth and parametric shift, especially at elevated temperatures above 85°C.

How does the 'A' grade differ from 'B' grade in capacitance tolerance?

The 'A' grade (ZC831Axx) guarantees capacitance within ±10% of the nominal 15.0 pF value at 2 V, while the 'B' grade (ZC831Bxx) tightens this to ±5%. This tighter tolerance reduces binning requirements in high-accuracy VCXO manufacturing and improves yield in matched-array filter designs.

Is the SOT23 package lead-free and RoHS compliant?

Yes, ZC831ATC was manufactured under Zetex's green compliance program and meets EU RoHS Directive 2011/65/EU. All solderable terminations are 100% matte tin-plated, and the molding compound contains no brominated flame retardants or heavy metals above threshold limits.

Can ZC831ATC be used in series-tuned configurations?

No-ZC831ATC is designed exclusively for shunt-tuned applications (e.g., across crystal terminals or LC tank nodes). Its hyperabrupt profile and low Q at high frequencies make it unsuitable for series-resonant tuning, where low series resistance and flat C–V slope are required; use dedicated series-tuned varactors like BBY40 instead.