Column: Design with frequency components


32.768kHz crystal – More than just a beat


In this series we will focus on the diff erent component types for timing, synchronization and frequency control, their basic parameters and how to best use them in various applications


By Daphne Popescu, Product and Sales Management, and Wendy Stewart, Sales and UK Offi ce Manager, GEYER Electronic


U


sing two crystals in the same design – one for the main high- frequency system clock and one for a standby/ low-power clock – is a


very common pattern in embedded and electronic systems. Complementing the design aspects


and rules that we covered in the three previous contributions of this series, we will here focus on the role and design aspects for the 32.678kHz crystal, also known as tuning fork crystal. This is a special type of quartz crystal vibrating mechanically in the shape of a tuning fork when an electric field is applied. The tuning fork is formed mechanically from the crystal by sawing or etching and has a different X or XY cut to conventional crystals, which usually show an AT cut. Due to their special shape, clock


crystals: • oscillate with a comparatively very low fundamental frequency;


• oscillate typically on 32.768kHz, which is 215Hz;


• are used as real-time clocks (RTCs) and low-power timing;


• are stable, low-power and small; • ensure an improved starting reserve and shorter starting time;


• are reliable while having a reduced quartz load;


Table 3: Comparison between alternatives


Table 1: A checklist for obtaining a good design Table 2:


Comparison between 12.5pF and 7pF clock crystals


• are not suitable for high-speed applications. Two-crystal designs (main +


standby) are extremely common whenever precise timekeeping and low-power operation is needed. They are used in most micro- controllers with RTC, wireless


www.electronicsworld.co.uk December 2025/January 2026 20


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