Compact 32.768 kHz tuning fork crystal provides stable output
The surface-mount ECX-31B crystal from ECS Inc. is ideal for industrial applications, and offers various load capacitance options. These crystals are recommended for use in STMicroelectronics microcontroller and microprocessor reference designs.
The ECX-31B from ECS Inc. is a series of 32.768 kHz tuning fork crystals which provide a stable output over an industrial operating-temperature range of -40ºC to 85ºC.
All versions of the ECX-31B are supplied in an industry-standard, surface-mount 3.2 mm x 1.5 mm x 0.9 mm package with a two-pad footprint, offering an equivalent series resistance of 70 kΩ. As standard, these crystals are specified with ±20 ppm frequency tolerance. A ±10 ppm tolerance option is available.
Various part numbers in the ECX-31B series can be specified to choose load capacitance options of 6 pF, 7 pF, 9 pF or 12.5 pF.
STMicroelectronics recommends ECS timing solutions for use with its STM32 families of microcontrollers and microprocessors. Advice about integrating crystals into STM32-based designs may be found in the ST application note AN2867.
Useful link
STM32 crystal selection tool