Industrial RTC Crystal Family | FCT 32.768 kHz Series

The FCT family covers a wide range of 32.768 kHz tuning-fork crystals in SMD and leaded packages. In real deployments, they keep timekeeping stable for PLCs and HMIs, industrial gateways/routers, power & energy controllers, smart meters, and portable field instruments—especially when systems rely on backup batteries or supercapacitors.

32.768 kHz RTC Low drive level Industrial temperature Long-term stability Battery-backed time

What this family helps you achieve in industrial equipment:

Accurate timestamps for alarms, events and production logs.
Reliable scheduling for maintenance, metering cycles and firmware updates.
Backup timekeeping during outages for meters, controllers and edge nodes.
Low-power operation that protects battery life and reduces standby current.

Tip: RTC accuracy depends on both the crystal and the oscillator network. Matching load capacitance (CL) and minimizing stray capacitance are key to controlling frequency offset.

FCom Fuji Crystal FCT 32.768 kHz industrial RTC crystal family in multiple packages

Family Overview

The FCT family provides 32.768 kHz tuning-fork crystals in a variety of SMD and through-hole packages. They are designed to keep real-time clocks accurate and low-power in industrial controllers, gateways, power and energy systems, smart meters and embedded devices.

Typical use cases include time-stamped event logging, duty-cycled sensing, scheduled communication windows, maintenance tracking, and backup timekeeping when the main supply is interrupted.

Application Directions

32.768 kHz RTC crystals are widely used wherever equipment must preserve time across sleep modes, brownouts or planned shutdowns. Below are representative industrial directions where the FCT family is commonly deployed.

Industrial Automation (PLC/HMI)

Keeps event logs and production records consistent; supports scheduled tasks and alarm timestamps even during power interruptions.

Industrial Gateways & Routers

Maintains system clock for security certificates, log correlation and network event auditing; improves reliability for battery-backed edge nodes.

Power & Energy Controllers (UPS/ESS)

Preserves maintenance intervals and fault timelines; supports outage reporting and service scheduling with stable timekeeping.

Smart Meters & Infrastructure Monitoring

Ensures accurate time-of-use metering, periodic sampling windows and long-term timestamp integrity for compliance and analytics.

Portable Field Instruments

Enables low standby current and reliable timekeeping with small batteries; ideal for handheld scanners, testers and data loggers.

Embedded Control & Industrial IoT

Supports sleep/wake scheduling, periodic reporting and timestamped sensor data in long-life industrial deployments.

Key Series and Packages

FCT-3M – Compact 3215 SMD RTC Crystal

FCT-3M is a popular RTC crystal for dense industrial and embedded boards:

3215 SMD package for compact controllers, gateways and communication modules.
32.768 kHz frequency with multiple load capacitance options such as 6–12.5 pF.
Low driving power to support ultra-low-current RTC blocks in MCUs and PMICs.
Industrial and extended temperature options for harsh environmental conditions.

FCT-1M / FCT-1S / FCT-2M – Larger and Legacy Packages

These series provide larger SMD or through-hole footprints where PCB area is less critical and mechanical robustness is preferred:

FCT-1M / FCT-1S – robust packages suitable for rack equipment and desktop instruments.
FCT-2M – mid-size SMD package for industrial controllers and power systems.

They are ideal when you value assembly robustness, mechanical strength or compatibility with existing designs over minimum footprint.

FCT-6M / FCT-8M – Long-Body SMD Crystals

FCT-6M and FCT-8M use elongated SMD packages that help with creepage distance and dielectric spacing on high-voltage or high-insulation boards:

Suitable for power electronics, energy meters and high-voltage control boards.
Helps routing around high-voltage nets while maintaining clearances.
Provides the same 32.768 kHz RTC function with a mechanically robust footprint.

Recommended FCom RTC Crystal Series

The table below lists representative FCT series commonly used across industrial control, gateways, power systems and metering equipment.

Series	Package	Typical Use	Learn More
FCT-3M	3.2 × 1.5 mm SMD	Compact PLC I/O modules, gateways and communication boards with battery-backed RTC.	FCT-3M Product Page
FCT-2M	Mid-size SMD	Industrial control boards and power controllers requiring a robust RTC footprint.	FCT-2M Product Page
FCT-6M	Long-body SMD	UPS/ESS controllers and energy boards with higher spacing and insulation needs.	FCT-6M Product Page
FCT-8M	Long-body SMD	Smart meters and power quality analyzers with extended creepage requirements.	FCT-8M Product Page

Typical Electrical Performance

The FCT family offers a selection of grades to match different RTC accuracy and power targets:

Nominal frequency: 32.768 kHz tuning-fork resonators.
Load capacitance: common values such as 6, 7, 9 and 12.5 pF, with custom options.
Frequency tolerance at 25 °C: typically ±10 ppm to ±30 ppm depending on the selected grade.
Stability over temperature: suitable for industrial ranges, such as −40 °C to +85 °C or higher.
Drive level: in the sub-microwatt range, supporting low RTC current consumption.

Design Guidelines for RTC Crystals

Match CL to the RTC oscillator block. Use the MCU/PMIC recommended load capacitance as your starting point to minimize frequency offset.
Keep traces short and symmetric. Route both crystal connections symmetrically and close to the RTC pins to reduce stray capacitance and noise pickup.
Limit drive level. Ensure the RTC oscillator drive level stays within the crystal’s recommended range to avoid accelerated aging.
Plan for temperature exposure. For outdoor or unconditioned deployments, select industrial or extended temperature variants to maintain accuracy.
Design the backup supply path. Pair the RTC with a properly sized backup battery or supercapacitor so timekeeping continues through outages.

FAQ – Industrial RTC Crystal Family

How do I choose the right FCT package for my design?

Start from your PCB density, assembly method and insulation requirements. Compact embedded boards often choose FCT-3M; larger industrial PCBs may prefer FCT-1M or FCT-2M; power and energy boards that need more spacing can use long-body options such as FCT-6M or FCT-8M.

What load capacitance should I select for my RTC crystal?

Check your MCU or PMIC datasheet for the recommended load capacitance and internal capacitance. Then choose the closest FCT load value and adjust any external capacitors so the effective load matches the target within tolerance.

Which industrial applications benefit the most from 32.768 kHz RTC crystals?

Applications that need reliable timestamps and low-power backup timekeeping—such as PLCs and HMIs, industrial gateways/routers, smart meters, UPS and energy storage controllers, and portable field instruments—commonly use 32.768 kHz RTC crystals.

Designing industrial equipment that depends on accurate timekeeping? FCom Fuji Crystal can help you select the right FCT RTC crystal and oscillator configuration to balance accuracy, power and lifetime for your specific use case.

Explore related resources: Why Timing Crystals Matter · Selecting a Timing Crystal · What Are Timing Devices?

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