FCT-1S — 32.768 kHz SMD Tuning Fork RTC Crystal (1.2×1.0 mm)

FCT-1S is an ultra-small 1.2×1.0×0.5 mm SMD tuning fork crystal designed for low-power RTC timekeeping in consumer and always-on clock domains. Common CL options (6/7/9/12.5 pF) and controlled ESR (≤ 90 kΩ) support start-up margin verification across wide temperatures, including many industrial/automotive/medical use cases.

RoHS & REACH compliant, Pb-free AEC-Q200 available (contact for options) Ultra-small 1.2×1.0×0.5 mm SMD package 32k RTC for low-energy timekeeping Operating temperature up to +125°C

Request Pricing / Samples Download Datasheet (PDF) RFQ Checklist

F32.768 kHz

Pkg1.2×1.0×0.5 mm

CL6 / 7 / 9 / 12.5 pF

ESR≤ 90 kΩ

DriveTyp 0.1 µW (Max 0.5)

Topr-40 to +125 °C

Overview

Engineering quick view

Nominal frequency: 32.768 kHz
Operating temperature: -40 to +125 °C
Load capacitance (CL): 6 / 7 / 9 / 12.5 pF (or specify)
ESR (max): 90 kΩ
Drive level: typ 0.1 µW, max 0.5 µW
Shunt capacitance (C0): 1.5 pF
Temp. coefficient: -0.034 to -0.039 ppm/T²
Aging: ± 3 ppm (1st year)
Insulation resistance: ≥ 500 MΩ (DC100V±15V)

Test condition (typical): ambient temperature 25 ± 5°C; relative humidity 40% to 70%.

Procurement quick view

Part number: FCT-1S
Package: 1.2×1.0×0.5 mm SMD
Compliance: RoHS & REACH, Pb-free
Datasheet: Download PDF
RFQ must include: CL, tolerance & temp range, quantity, packing
Support: start-up margin review (ESR / drive / RTC conditions)

Key Features

Ultra small size: 1.2×1.0×0.5 mm
High reliability environmental performance
High frequency stability and high precision
RoHS & REACH compliant, Pb-free

If you have special requirements (custom CL, tighter tolerance, screening, packing), share your RTC oscillator conditions and expected start-up criteria.

Compare: FCT-1M Compare: FCT-2M Compare: FCT-2T Compare: FCT-3M

Ordering Options

Select frequency tolerance and temperature range to match your RTC accuracy budget and operating environment.

Item	Options / Notes
Part number	FCT-1S
Nominal frequency	32.768 kHz
Frequency tolerance (at 25°C)	±5 / ±10 / ±20 ppm @ -40 to +85°C ±10 / ±20 / ±30 ppm @ -40 to +105°C ±10 / ±20 / ±30 ppm @ -40 to +125°C
Operating temperature	-40 to +125 °C
Load capacitance (CL)	6 / 7 / 9 / 12.5 pF (or specify)
Drive level	Typ. 0.1 µW, Max. 0.5 µW
ESR (max)	90 kΩ
Shunt capacitance (C0)	1.5 pF
Temperature coefficient	-0.034 to -0.039 ppm/T²
Insulation resistance	≥ 500 MΩ (DC100V±15V)
Aging	± 3 ppm (1st year)
Package	1.2×1.0×0.5 mm SMD

RFQ Checklist (copy/paste)

Target CL

6 / 7 / 9 / 12.5 pF (or specify)

Tolerance & temp range

Choose: -40~85 / -40~105 / -40~125 (ppm options above)

Quantity & forecast

Prototype / pilot / mass production volumes

Packing

Tape & reel, labeling requirements (if any)

RTC details (recommended)

Expected drive, start-up criteria, PCB constraints/noise environment

Selection Path / Upgrade Options

Start from your RTC requirement (CL + drive + start-up margin), then select temperature grade and screening. For footprint alternatives or sourcing flexibility, see FCT-2M (2.0×1.2mm), FCT-2T (cylinder), or the RTC Crystal Family. For system selection notes, use the 32.768 kHz RTC Crystal Guide.

Design Tips (Engineering)

Start-up margin & ESR

Verify RTC start-up using the worst-case ESR (max 90 kΩ) across temperature.
Include board parasitics and component tolerance in the oscillator network budget.
If margin is tight, evaluate nearby CL options or compare packages (FCT-1M, FCT-2M).

CL selection & low-power drive

Match crystal CL to your RTC requirement (6/7/9/12.5 pF).
Keep drive low to reduce long-term drift: typ 0.1 µW, max 0.5 µW.
Route the 32k crystal as a “quiet island”: short traces, guard from switching edges, clean ground return.

Electrical Specifications

Table shows common specifications. If you require special specifications, please contact FCom sales.

Parameter	Symbol	Min.	Typ.	Max.	Units	Notes
Nominal Frequency	F	-	32.768	-	kHz	-
Frequency Tolerance (at 25°C)	FT	±5 / ±10 / ±20 @ -40~85°C ±10 / ±20 / ±30 @ -40~105°C ±10 / ±20 / ±30 @ -40~125°C			ppm	-
Operating Temperature	Topr	-40	25	125	°C	-
Load Capacitance	CL	6, 7, 9, 12.5 or specify			pF	-
Drive Level	DL	-	0.1	0.5	µW	-
Equivalent Series Resistance	ESR	-	-	90	kΩ	-
Shunt Capacitance	C0	-	1.5	-	pF	-
Temperature Coefficient	-	-	-0.034	-0.039	ppm/T²	-
Insulation Resistance	-	500	-	-	MΩ	DC100V±15V
Aging	-	-	±3	-	ppm	1st year

Test condition: ambient temperature 25 ± 5°C; relative humidity 40% to 70%.

Applications

Consumer products
Real Time Clock (RTC)
Always-on clock domains in wearables and low-power IoT

Why these specs matter: low drive helps protect long-term stability in battery systems, while controlled ESR supports start-up margin across temperature in portable, industrial, automotive and medical devices. For selection notes by environment and load, see the 32.768 kHz RTC Crystal Guide for Industrial, Auto & Medical.

Related options for footprint or sourcing flexibility:

Package & Dimensions

Package: 1.2×1.0×0.5 mm SMD. Refer to the drawing for pad orientation (#1 / #2) and suggested land pattern.

Suggested layout (typ.): 0.4 mm / 0.3 mm / 0.4 mm pad widths; 1.0 mm pad length (see drawing)
Connection: pads #1 and #2 as shown in the dimensions drawing

FCT-1S package dimensions and suggested PCB land pattern for 1.2×1.0×0.5mm SMD tuning fork RTC crystal (pads #1/#2)

Resources

Datasheet (PDF): Download
Category: Tuning Fork Crystals
Contact form: Sales / Technical Support
Support: FCom@fujicrystal.com

Selection & design guides

Certifications (internal)

FCT-1M FCT-2M FCT-2T FCT-3M Tuning Fork Crystals

Get Pricing / Samples

For the fastest quotation, include CL, tolerance & temperature range, quantity, and packing. If you have RTC start-up criteria, we can help review ESR/drive margin.

Email RFQ Contact Form RFQ checklist

What happens next

Confirm options (CL / tolerance / temperature range) and availability.
Provide quotation and (if requested) sample plan for engineering validation.
Support compliance documents and traceability needs.

FAQ

Which load capacitance (CL) should I choose for FCT-1S?

Choose CL to match your RTC oscillator specification. Common options are 6, 7, 9, and 12.5 pF. If your RTC requires a different CL, request a custom option when quoting.

How does ESR affect RTC start-up margin?

ESR directly impacts start-up. Verify your RTC start-up criteria using the worst-case ESR (≤ 90 kΩ) across temperature and component tolerance.

What drive level should be used for FCT-1S?

Use low drive to avoid overdrive and long-term drift. FCT-1S drive level is typically 0.1 µW with a maximum of 0.5 µW; keep the RTC drive within this range.

Why is there no online price for FCT-1S?

RTC crystals are configured by CL, tolerance, temperature range, screening and packing. For accurate pricing, send your target options and quantity for an RFQ.

What are typical MOQ and lead time?

MOQ and lead time depend on CL, tolerance/temperature grade, screening, and packing. Contact us with your target configuration and quantity; we will confirm current MOQ/lead time and suggest alternatives if needed.

Do you provide samples and customization?

Yes. We support samples for design validation, volume production, and customization such as CL options, tighter tolerance, screening, and packing. Share your RTC conditions and requirements when requesting an RFQ.

Is FCT-1S compliant with RoHS and REACH?

Yes. FCT-1S is RoHS and REACH compliant and Pb-free. Compliance documents and traceability information can be provided upon request.