32k Low-Power RTC Crystal

FCT-8M — 32.768 kHz SMD Tuning Fork Crystal (3.8×8.0 mm)

Q: How do I request pricing, MOQ, lead time, samples, or customization?

This product is quoted on request. Contact FCom for RFQ, MOQ and lead time, sample availability, packaging options, and test/report needs. Custom CL and special screening can be supported upon review.

FCom Fuji Crystal FCT-8M is a production-ready 32.768kHz tuning fork RTC crystal in an industry-standard 3.8×8.0mm SMD package. Built for automated pick-and-place and reflow soldering, it offers multiple load capacitance options to match mainstream MCU/RTC designs in low-power timekeeping and always-on clock domains.

32.768 kHz SMD 3.8 × 8.0 mm RTC / MCU Clock Reflow Compatible

Frequency

32.768 kHz

Package

3.8 × 8.0 mm SMD

Temp Range

-40~90 °C

CL Options

6 / 7 / 9 / 12.5 pF

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Overview

FCT-8M is a 32.768 kHz tuning fork crystal intended for real-time clock (RTC) and low-power time base functions in MCUs, PMICs and dedicated RTC ICs. Its industry-standard 3.8×8.0mm SMD package helps reduce redesign risk and accelerates qualification when migrating from legacy 32k crystals.

Stable time base for always-on and deep-sleep domains.
CL options aligned with mainstream reference designs.
SMT and reflow ready for volume manufacturing.

For a broader view of tuning fork timing crystals and selection logic, you may also reference our portfolio pages.

Key Features

Engineering Highlights

Nominal frequency: 32.768 kHz.
CL options: 6 / 7 / 9 / 12.5 pF (custom on request).
Low drive requirement suitable for battery-powered systems.
ESR control supports reliable RTC start-up when matched to the IC.
Operating temperature: -40~90 °C.

Production & Procurement

Industry-standard 3.8×8.0mm footprint.
Optimized for automated placement and reflow soldering.
RoHS & REACH documentation available with controlled revisions.
Lot traceability and CoC support for project qualification.

Key features reflect typical configurations. Final delivered specs depend on the confirmed part suffix and the latest official datasheet.

Design Tips

Load Capacitance Selection

Match CL to the effective load seen at the RTC/MCU pins.
Account for internal capacitor settings and PCB parasitics.
When uncertain, validate with two adjacent CL options during EVT.

Start-up Validation

Verify oscillation across temperature corners and battery range.
Confirm cold-start and wake-from-deep-sleep stability.
Review ESR margin against the IC’s negative resistance guideline.

Drive Level Control

Keep drive within the specified maximum (typ. 1.0 µW) to protect long-term stability.
Excess drive may accelerate aging and frequency drift.
Follow chip vendor recommendations for oscillator gain settings.

These tips are intentionally concise for a product page. FCom can provide more detailed RTC debug and error-mitigation guidance for project qualification.

Electrical Specifications

Parameter	Symbol	Specification	Unit	Notes
Nominal Frequency	F	32.768	kHz	at 25±5°C
Frequency Tolerance (options)	FT	±5 / ±10 / ±20	ppm
Operating Temperature	Topr	-40 to +90	°C	Shown as -40~90°C in ordering
Load Capacitance	CL	6 / 7 / 9 / 12.5 or specified	pF
Drive Level (Max.)	DL	1.0	µW
Equivalent Series Resistance (Max.)	ESR	50	kΩ
Shunt Capacitance (Typical)	C0	1.6	pF
Temperature Coefficient (Parabolic)	—	-0.035 ± 0.01	ppm/°C²
Insulation Resistance	—	≥ 500	MΩ	DC100V ±15V
Aging (Typical)	—	± 3	ppm	First year

Specifications are provided for design-in guidance. Please confirm the latest datasheet before tape-out and mass production.

Stability vs Temperature

Like most tuning fork RTC crystals, FCT-8M exhibits a predictable parabolic frequency-temperature characteristic. System-level time accuracy depends on the selected tolerance grade, CL matching, oscillator margin and the end-product’s real thermal profile.

Use tighter tolerance options for stricter OS time budgets.
Validate frequency offset at your real CL and layout.
Consider calibration/compensation strategies in wide daily temperature swings.

Recommended Applications

Wearables & Health Devices
Stable low-power RTC timing for always-on sensing and intermittent wake-up.

Smart Home & IoT Nodes
Reliable time base for low-duty-cycle wireless sensors and controllers.

Utility & Industrial Meters
Long-life timekeeping with mature 3.8×8.0mm supply ecosystem.

For industrial deployments, prioritize the -40~90°C option and consult FCom for project-level qualification or tighter stability needs.

Package

FCT-8M adopts an industry-standard 3.8×8.0mm SMD tuning fork crystal package designed for automated assembly and reflow soldering. This mature footprint helps simplify cross-vendor qualification and minimizes redesign risk for RTC and low-power MCU platforms.

Package size: 3.8 × 8.0 mm (SMD)
Automation-ready for high-volume SMT
Suitable for mainstream RTC/MCU reference designs

Resources

A unified resources block improves both engineer validation speed and procurement confidence.

Package outline (reference)
FCT-8M SMD tuning fork RTC crystal package outline (3.8×8.0mm)

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Selection Checklist

Model FCT-8M
Frequency 32.768 kHz
CL 6 / 7 / 9 / 12.5 pF
Tolerance ±5 / ±10 / ±20 ppm
Temp Range -40~90°C

Procurement-Friendly Part Description (Example)

Field	Meaning	Example
Series	Product family	FCT-8M
Frequency	Nominal frequency	32.768k
CL	Load capacitance	CL12.5
Tolerance	Frequency tolerance	10ppm
Temp Range	Operating range	-40~90

Selection Path / Upgrade Options

Explore the broader family for different footprints and supply ecosystems: RTC Crystal Family
Related 32.768kHz SMD RTC crystals: FCT-2M, FCT-3M, FCT-6M
Design & selection references: Industrial/Automotive/Medical RTC Guide and Tuning-Fork vs AT-cut

RFQ Information

Recommended Order Information
Model	FCT-8M
Frequency	32.768 kHz
CL	6 / 7 / 9 / 12.5 pF (target)
Tolerance	±5 / ±10 / ±20 ppm (target)
Temperature Range	-40~90°C
Annual Volume	____ pcs
Target First-Build Date	____

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Final part definition should follow your internal coding system and the latest FCom datasheet.

FAQ

Is FCT-8M footprint-compatible with common 32k SMD crystals?

FCT-8M follows an industry-standard 3.8×8.0mm SMD form factor. For best results, verify pad dimensions, orientation and electrical limits against your MCU/RTC reference circuit.

How can I improve first-pass oscillation start-up?

Place the crystal close to the RTC/MCU pins and keep traces short.
Avoid routing near high-frequency clocks, DC/DC switches, RF sections or high-current loops.
Maintain a clean ground reference and symmetric routing.
Ensure actual drive level and effective load match the crystal spec.

Can FCom provide special CL or tighter tolerance versions?

Yes. The parameters on this page reflect common options. FCom can support custom CL, tighter tolerance, or project-specific reliability combinations upon engineering review.

What about MOQ, lead time, samples, packaging, and test reports?

This product is quoted on request. Contact FCom for MOQ and lead time, sample availability, packaging options, and test/report needs. Custom CL and special screening can be supported upon review.

Contact FCom Fuji Crystal

If you are evaluating a 32.768kHz RTC solution or need a stable, production-ready supply option with responsive engineering support, reach out to FCom for samples, pricing and design-in assistance.

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For application engineering support (layout review, start-up margin checks, CL validation), contact technical support via Contact.