Diodes Incorporated ZC836ATC

Overview

ZC836ATC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators. It delivers 100 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), Q ≥ 100 at 50 MHz, and ultra-low reverse leakage (200 pA typ.), enabling low-phase-noise VCXO/TCXO designs in SOT23 surface-mount packages.

For engineers reviewing the ZC836ATC datasheet, ZC836ATC pinout, ZC836ATC application, or ZC836ATC equivalent, key selection criteria include its hyperabrupt CV slope for steep tuning response, high Q at RF frequencies, tight capacitance tolerance (±10%), and compatibility with miniature SMT layouts in timing-critical wireless infrastructure and mobile radio front-ends.

Technical Context

The ZC836ATC employs a hyperabrupt junction profile to achieve a steep, linearized C–V response-critical for minimizing tuning nonlinearity in voltage-controlled crystal oscillators. Its 25 V reverse breakdown rating and −55°C to +150°C operating range support robust operation in temperature-compensated modules.

Designed specifically for 2–20 V tuning voltage ranges, it exhibits a temperature coefficient of capacitance of +300 to +400 ppm/°C, requiring compensation in high-stability TCXOs. The device's low IR ensures minimal bias current-induced phase perturbation in low-power oscillator bias networks.

Key Specifications

Pinout & Package

Package: SOT23 - 3-pin plastic surface-mount package (2.67 × 1.20 × 1.10 mm), anode/cathode configuration with cathode marked by band.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SMV1232–079LF and BBY58–02W, the ZC836ATC uniquely balances high tuning ratio (5.0–6.5), tight capacitance tolerance (±10%), and sufficient Q (≥100) for stable VCXO/TCXO operation-making it optimal for mid-tier wireless infrastructure where linearity and manufacturability outweigh marginal Q gains.

Availability

ZC836ATC is available at Aetrix Electronics and suitable for VCXO modules, TCXO reference tuning, and mobile radio transceivers requiring stable component supply with consistent hyperabrupt CV performance and RoHS-compliant SMT packaging.

Supply support for ZC836ATC 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 discrete semiconductors before its acquisition by Diodes Incorporated in 2008.

The 830 series varactors-including ZC836ATC-were engineered for frequency control in wireless timing systems, emphasizing hyperabrupt CV linearity, low phase noise, and miniature SMT reliability in mobile and infrastructure applications.

FAQ

What is the maximum recommended reverse voltage for continuous operation?

The ZC836ATC has a rated reverse breakdown voltage of 25 V at I_R = 10 µA. For reliable long-term operation, Zetex specifies a maximum continuous reverse voltage of 20 V-exceeding this risks irreversible junction degradation and increased leakage. Derating to 15 V is advised in thermally stressed environments or where voltage transients may occur.

Does ZC836ATC require external biasing components for VCXO use?

Yes-ZC836ATC requires a clean, low-noise DC bias voltage (0–20 V) applied to its anode, with the cathode referenced to the oscillator's RF ground. A series 1 kΩ resistor and parallel 100 nF ceramic capacitor are recommended between the tuning voltage source and anode to suppress noise and prevent RF feedback into the control line.

Is the SOT23 package lead-free and RoHS compliant?

Yes-the ZC836ATC SOT23 package is fully RoHS compliant per Directive 2011/65/EU, with lead-free matte tin plating on terminations and halogen-free molding compound. Zetex confirmed green compliance in Issue 11 (January 2007) datasheet, and all units shipped post-2006 meet WEEE and ELV directive requirements.

How does temperature affect capacitance tuning accuracy?

The ZC836ATC exhibits a positive temperature coefficient of capacitance (+300 to +400 ppm/°C), meaning capacitance increases ~0.3–0.4% per °C rise. In TCXOs, this necessitates either analog compensation (e.g., NPO capacitor network) or digital correction using temperature-sensed lookup tables to maintain frequency stability within ±0.5 ppm over −40°C to +85°C.