Diodes Incorporated ZDC834ATA

Overview

ZDC834ATA from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators and RF filters. It delivers 47.0 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), ≥200 Q at 50 MHz, and ultra-low reverse leakage (200 pA typ.), enabling low-phase-noise VCXO/TCXO designs in wireless infrastructure.

For engineers reviewing the ZDC834ATA datasheet, ZDC834ATA pinout, ZDC834ATA application, or ZDC834ATA equivalent, key selection criteria include its 25 V reverse breakdown rating, SOT23 package compatibility, hyperabrupt CV slope for steep tuning response, and guaranteed low IR performance critical for oscillator phase noise floor.

Technical Context

ZDC834ATA operates as a voltage-variable capacitor with hyperabrupt doping profile, delivering nonlinear C–V response ideal for wide-range frequency pulling in crystal oscillator circuits. Its capacitance varies from 42.3 pF (min) to 51.7 pF (max) at VR = 2 V, f = 1 MHz, and drops to ~7.3–9.0 pF at VR = 20 V.

The device exhibits a temperature coefficient of capacitance of +300 to +400 ppm/°C and maintains ≥200 Q factor at 50 MHz under 3 V bias - confirming suitability for stable, high-selectivity RF tuning networks where loss and thermal drift must be minimized.

Key Specifications

Pinout & Package

ZDC834ATA is housed in a standard SOT23 surface-mount package (JEDEC TO-236AB), with cathode-marked lead configuration and 330 mW power dissipation rating at 25°C ambient.

Key Features

Applications

Equivalent & Alternatives

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

Compared with ZMV834ATA and ZC834ATA, ZDC834ATA offers optimal thermal performance in SOT23 for high-reliability VCXOs, while maintaining identical tuning linearity and phase noise contribution - making it the preferred choice for industrial-grade timing modules.

Availability

ZDC834ATA is available at Aetrix Electronics and suitable for VCXO design, TCXO manufacturing, and RF filter tuning requiring stable component supply with traceable lot control and RoHS-compliant packaging.

Supply support for ZDC834ATA 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 discrete semiconductors before its acquisition by Diodes Incorporated in 2008.

ZDC834ATA belongs to the 830-series hyperabrupt varactor family, engineered specifically for low-phase-noise frequency control in telecom timing systems and wireless transceivers where CV slope linearity and leakage stability are critical.

FAQ

What is the maximum recommended reverse voltage for continuous operation of ZDC834ATA?

The absolute maximum reverse voltage is 25 V, but Zetex specifies derated operation at ≤20 V for long-term reliability. At 20 V, reverse leakage remains ≤20 nA, and capacitance variation stays within datasheet limits - making 20 V the practical upper limit for production VCXO bias networks.

Does ZDC834ATA require special ESD handling during PCB assembly?

Yes - ZDC834ATA is rated Class 1B per JEDEC JS-001 (≤250 V HBM). Standard ESD-safe workstations, ionized air blowers, and grounded tweezers are mandatory. The SOT23 cathode marking must be verified pre-reflow to avoid reverse-bias damage during automated placement.

Can ZDC834ATA be used in series or parallel configurations for extended tuning range?

Parallel connection is valid and commonly used to double nominal capacitance (e.g., two ZDC834ATAs yield ~94 pF at 2 V), but series use is not recommended - mismatched CV curves cause nonlinearity, and combined breakdown drops to ~17 V, violating safe operating area.

Is ZDC834ATA compliant with RoHS and REACH regulations?

Yes - per Zetex's 2007 Green Compliance statement, ZDC834ATA is fully RoHS-compliant (Pb-free, Cd-free, Hg-free, Cr⁶⁺-free, PBB/PBDE-free) and meets REACH SVHC thresholds. Certificate of Compliance is available upon request with batch-specific traceability data.