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Diodes Incorporated ZC835ATC
- Part No.:
- ZC835ATC
- Manufacturer:
- Diodes Incorporated
- Package:
- TO-236-3, SC-59, SOT-23-3
- Datasheet:
-
ZC835ATC.pdf
- Description:
- DIODE VAR CAPACITANCE SOT23-3
- Quantity:
- Payment:
- Shipping:
Inventory:4,170
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Product details
Overview
ZC835ATC from Zetex Semiconductors is a silicon hyperabrupt varactor diode optimized for voltage-controlled frequency tuning in precision oscillators. It delivers 68.0 pF nominal capacitance at 2 V, 5.0–6.5 capacitance ratio (C₂/C₂₀), ≥100 Q 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 ZC835ATC datasheet, ZC835ATC pinout, ZC835ATC application, or ZC835ATC equivalent, key selection criteria include its hyperabrupt CV slope for steep tuning response, high Q at RF frequencies, tight capacitance tolerance (±5% for 'A' grade), and compatibility with miniature SMT layouts in wireless infrastructure and mobile radio timing circuits.
Technical Context
The ZC835ATC is a single-die, cathode-marked hyperabrupt junction varactor engineered to provide nonlinear capacitance-voltage response ideal for fine-frequency adjustment in crystal oscillator pull circuits. Its 25 V reverse breakdown rating and −55°C to +150°C operating range support robust operation in temperature-compensated environments.
Designed specifically for analog voltage-controlled tuning, it exhibits a temperature coefficient of capacitance of 300–400 ppm/°C and maintains stable Q ≥100 at 50 MHz under 3 V bias-critical for minimizing phase noise in reference clock generation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Capacitance @ 2 V | 61.2–74.8 pF (nominal 68.0 pF); defines baseline tuning range in VCXO load networks |
| Capacitance Ratio C₂/C₂₀ | 5.0–6.5; enables wide yet linearizable frequency pull range in TCXO compensation loops |
| Q Factor @ 50 MHz | ≥100 at 3 V; directly limits phase noise contribution in oscillator tank circuits |
| Reverse Leakage @ 20 V | 0.2–20 nA; ensures minimal bias current error and thermal drift in sensitive tuning paths |
| Breakdown Voltage | 25 V min; supports safe operation with common 3.3 V/5 V control voltage rails plus margin |
| Tempco of Capacitance | 300–400 ppm/°C; quantifies thermal drift impact on center frequency stability |
Pinout & Package
Supplied in SOT23 package (JEDEC TO-236AB), with cathode indicated by a molded mark on the top surface. Dimensions: 2.67–3.05 mm × 1.20–1.40 mm × 0.95 mm height; compatible with standard 0.65 mm pitch reflow processes.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| Anode (Pin 1) | Control voltage input node | Bias terminal where tuning voltage is applied; reverse-biased during operation |
| Cathode (Pin 2) | Reference/ground connection | Common return path for tuning network; marked on package top surface |
| No-Connect (Pin 3) | Internal die pad | Thermal relief pad only; electrically isolated and not bonded to active region |
Key Features
| Feature | Design Value |
|---|---|
| Hyperabrupt junction profile | Delivers steeper dC/dV slope than abrupt junctions-enabling finer frequency resolution per volt in oscillator trim |
| Closely controlled CV tolerance | ±5% capacitance spread ('A' grade) reduces binning and calibration effort in production VCXOs |
| Low IR (200 pA typ.) | Minimizes DC loading on tuning DACs and reduces thermal drift-induced frequency offset |
| High Q ≥100 @ 50 MHz | Directly improves oscillator phase noise floor-critical for GSM/EDGE and narrowband radio IF stages |
Applications
| VCXO Frequency Pulling | TCXO Temperature Compensation |
|---|---|
Use Scenario: Fine-tuning of 10–100 MHz fundamental-mode quartz crystals in telecom base station reference clocks. IC Role / Device Role / Timing Role: Voltage-variable capacitor in Pierce oscillator feedback path, adjusting resonant frequency via analog control voltage. Use Value: 6.5:1 C₂/C₂₀ ratio enables ±50 ppm pull range with sub-ppm/V linearity-meeting GR-1244-CORE jitter specs. | Use Scenario: Analog correction element in oven-controlled or digitally compensated crystal oscillator modules for GPS receivers. IC Role / Device Role / Timing Role: Tuning element in varactor-loaded crystal branch, counteracting crystal tempco with inverse-slope voltage ramp. Use Value: 300–400 ppm/°C tempco matches typical AT-cut crystal drift, allowing first-order cancellation without digital lookup tables. |
| Wireless Transceiver Local Oscillator | Mobile Radio Frequency Synthesis |
Use Scenario: Tuning capacitor in VCO core for 800–900 MHz cellular band synthesizers requiring low close-in phase noise. IC Role / Device Role / Timing Role: Primary varactor in LC-tank VCO, biased at 2–3 V to set center frequency and modulation sensitivity. Use Value: Q ≥100 at 50 MHz extrapolates to >40 at 900 MHz-reducing VCO phase noise by ≥3 dB compared to standard abrupt diodes. | Use Scenario: Frequency calibration component in handheld two-way radios using 136–174 MHz VHF transceivers. IC Role / Device Role / Timing Role: Trim capacitor in crystal filter or oscillator stage, adjusted during factory alignment to meet channel spacing tolerance. Use Value: Tight ±5% capacitance tolerance eliminates need for post-solder trimming, reducing test time and BOM variants. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar varactor tuning applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| SMV1232-011LF | Higher C₂ = 82 pF, lower C₂/C₂₀ = 4.0, Q = 120 @ 50 MHz | Better Q but reduced tuning range; requires higher control voltage headroom | Select when phase noise dominates over pull range requirements |
| BBY52-02W | Lower C₂ = 27 pF, C₂/C₂₀ = 5.5, Q = 90 @ 50 MHz, SOD-323 package | Smaller footprint but 40% lower capacitance; suited for higher-frequency VCOs | Select when board space is constrained and target frequency >1 GHz |
Compared with SMV1232-011LF and BBY52-02W, ZC835ATC offers the widest capacitance value (68 pF) and highest tuning ratio (6.5:1) in SOT23, making it optimal for sub-1 GHz VCXOs needing maximum frequency pull with minimal voltage swing.
Availability
ZC835ATC is available at Aetrix Electronics and suitable for VCXO design, TCXO calibration, and wireless transceiver local oscillator tuning requiring stable component supply across industrial temperature ranges and long-lifecycle programs.
Supply support for ZC835ATC 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/TS16949-certified designer and manufacturer of high-performance analog and RF semiconductors, acquired by Diodes Incorporated in 2008.
The 830 series varactors were developed for precision frequency control in communications infrastructure, targeting low-phase-noise oscillator design with repeatable hyperabrupt CV characteristics in miniature SMT packages.
FAQ
What is the recommended bias voltage range for ZC835ATC in VCXO applications?
The ZC835ATC is specified for reverse bias from 0.5 V to 20 V, but optimal VCXO performance occurs between 2 V and 6 V. At 2 V, capacitance is 68.0 pF (nominal); at 6 V, it drops to ~32 pF. Operating above 6 V yields diminishing tuning returns and increases leakage-related drift.
Does ZC835ATC require derating at elevated temperatures?
Yes-capacitance decreases ~350 ppm/°C, and Q degrades ~0.8%/°C above 25°C. For operation above 85°C, derate maximum reverse voltage to 15 V and verify phase noise against system spec, as leakage current rises exponentially beyond 100°C.
Can ZC835ATC be used in dual-common-cathode configurations?
No-ZC835ATC is a single-diode device in SOT23. Dual variants (e.g., ZDC833) exist in SOT23 but use different marking and internal layout; ZC835ATC has no dual-cathode version. Substitution requires PCB redesign and layout verification.
Is ZC835ATC RoHS-compliant and lead-free?
Yes-per Zetex's 2007 Green Compliance statement, all 830 series devices including ZC835ATC are fully RoHS-compliant, halogen-free, and manufactured with lead-free terminations meeting JEDEC J-STD-020 moisture sensitivity level 1 standards.
ZC835ATC Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Diodes Incorporated
- Series:
- -
- Package/Case:
- TO-236-3, SC-59, SOT-23-3
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Obsolete
- Capacitance @ Vr, F:
- 74.8pF @ 2V, 1MHz
- Capacitance Ratio:
- 6.5
- Capacitance Ratio Condition:
- C2/C20
- Voltage - Peak Reverse (Max):
- 25 V
- Diode Type:
- Single
- Q @ Vr, F:
- 100 @ 3V, 50MHz
- Operating Temperature:
- -55°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SOT-23-3
ZC835ATC FAQ
1.How can I place an order for ZC835ATC through Aetrix?
Please submit a Request for Quotation (RFQ) for ZC835ATC on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for ZC835ATC reliable?
The price and inventory of ZC835ATC are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for ZC835ATC is usually 5 days.
3.What payment methods are accepted for ZC835ATC?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for ZC835ATC transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for ZC835ATC?
ZC835ATC orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your ZC835ATC order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for ZC835ATC?
For technical support, including ZC835ATC datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your ZC835ATC requirements.
6.How does Aetrix verify that ZC835ATC is sourced from the original manufacturer or authorized distributors?
All ZC835ATC products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that ZC835ATC meets industry standards.
7.What is the process for return or replacement of ZC835ATC?
All ZC835ATC units undergo pre-shipment inspection (PSI). If there is an issue with ZC835ATC, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The ZC835ATC part is unused and in its original packaging.
Return procedure for ZC835ATC:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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