FCX-4U HC-49U Crystal 1.8–64 MHz Low ESR
DIP HC-49U
FEATURE
Product Description
FCX-4U Quartz Crystal Resonator (Resistance Welded HC-49U)
The FCX-4U is a resistance welded HC-49U quartz crystal resonator designed for stable clock generation across a wide frequency range. With higher pullability and low ESR, it supports reliable oscillator startup in consumer electronics, instruments, computer peripherals, and FPGA/MCU timing designs.
Key Specs
Test condition note (typical): ambient temperature 25 ± 5°C, relative humidity 40%–70%.
- Frequency range: 1.8–64 MHz
- Tolerance: ±30 ppm @25°C (±3°C)
- Operating temperature: -40°C to +85°C
- Low ESR bands: down to 40 Ω (7–54 MHz band)
- CL options: 10 pF / 18 pF / 20 pF (custom available)
Key Features
- Resistance welded type crystal units
- Higher pullability and lower equivalent series resistance (ESR)
- RoHS and REACH compliant, Pb-free
Typical Applications
- Consumer Electronics
- Test and Measurement
- Computer Peripherals
- FPGA / Microcontrollers
Applications: Why These Specs Matter
FPGA / MCU clocks (robust startup margin)
Low ESR and appropriate drive level limits improve startup margin when using on-chip Pierce oscillators. Selecting the right CL helps close frequency accuracy targets after board-level stray capacitances.
Peripherals & consumer electronics (frequency coverage + supply flexibility)
A wide frequency range (1.8–64 MHz) supports common system clocks for USB peripherals, controllers and embedded modules. Samples, volume supply and customization allow quick validation and smooth scale-up.
Test equipment (stability and repeatability)
Specified tolerance/stability and aging help maintain repeatability across temperature and service life, which is useful for measurement instruments and calibration-sensitive subsystems.
Detailed Specifications
| Parameter | Symbol | Min | Typ | Max | Unit | Notes |
|---|---|---|---|---|---|---|
| Nominal Frequency | F | 1.8 | – | 64 | MHz | Common specification |
| Frequency Tolerance | FT | – | ±30 | – | ppm | @25°C ±3°C |
| Frequency Stability Over Operating Temp. Range (Reference 25°C) | ST | – | ±50 | – | ppm | @-20~70°C |
| – | ±50 | – | ppm | @-40~85°C | ||
| Operating Temperature | Topr | -40 | 25 | 85 | °C | Common specification |
| Load Capacitance | CL | – | 10 / 18 / 20 or specify | – | pF | Custom CL available |
| Drive Level | DL | – | 100 | 500 | µW | Keep within limits |
| Equivalent Series Resistance (max) | ESR | – | – | 300 | Ω | 1.8–2.4 MHz |
| – | – | 200 | Ω | 2.4–3.5 MHz | ||
| – | – | 80 | Ω | 3.5–7 MHz | ||
| – | – | 40 | Ω | 7–54 MHz | ||
| – | – | 80 | Ω | >54 MHz | ||
| Aging | – | – | ±3 | – | ppm | 1st year |
Test condition: ambient temperature 25 ± 5°C, relative humidity 40%–70%. The table shows common specifications. If you have special requirements, please contact our salesperson.
Package Dimensions (mm)
Body Outline (Max.)
- Width
- 10.3 Max
- Length
- 11.5 Max
- Thickness
- 5 Max
- Case height (H)
- 13.50 Max (HC-49U)
Leads / Mounting
- Lead diameter
- 0.43 ± 0.05
- Lead pitch
- 4.88 ± 0.2
- Lead length
- 20 Max
- Integration note
- Confirm hole diameter and keep-out in the PCB footprint based on your assembly process.
Ordering Code / Options
To configure FCX-4U quickly, please include the following in your inquiry:
- Frequency (MHz) and target frequency offset requirement
- Load capacitance (CL) (10 / 18 / 20 pF or custom)
- Tolerance (FT) @25°C
- Stability (ST) and temperature range (e.g., -40~85°C)
- Quantity, sampling needs, and target delivery schedule
Selection Path / Upgrade Options
Need different form factors or integration paths? Explore HC-49S, FCX-5U, FCX-9M (HC-49 SMD), or the Quartz Crystal Resonators family. For system-level selection, see the application notes below.
Documents & Downloads
- FCX-4U Datasheet (PDF)
- Certifications: ISO9001 · ISO14001
- Technical support & applications engineering: Contact page
Recommended reading (News)
- Frequency Crystal Science
- What Is Resonant Frequency?
- Quartz Frequency Guide
- Quartz Crystal Frequency Ranges
Application notes
Frequently Asked Questions (FAQ)
What is the FCX-4U crystal?
FCX-4U is a resistance welded quartz crystal resonator in an HC-49U package. It targets stable clock generation with higher pullability and low ESR for reliable oscillator startup.
What frequency range does FCX-4U support?
FCX-4U supports nominal frequencies from 1.8 MHz to 64 MHz. Standard and custom frequencies are available depending on your tolerance, stability and CL requirements.
What load capacitance (CL) options are available?
Common CL options include 10 pF, 18 pF and 20 pF. Custom CL can be specified on request.
Can FCX-4U be customized?
Yes. Frequency and load capacitance (CL) can be specified. Share your target frequency, CL, tolerance, stability, operating temperature range and volume for configuration support.
Do you offer samples and what is the typical lead time?
Samples are available for evaluation. Lead time depends on frequency, CL, screening and order quantity. Contact FCom with your target specs for the latest schedule.
What information should I include in an RFQ?
Include frequency, CL, tolerance (FT), stability (ST) and temperature range, quantity and target delivery. This helps us quote efficiently without listing public pricing.
Explore More
Note: Specifications shown are common configurations for reference. Final parameters may vary by frequency, CL, screening level and customer requirements. For applications engineering support, please contact FCom.
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