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ST's serial real-time clocks range from ultra-low power devices for portable applications to high-accuracy parts with analog calibration up to factory-calibrated RTC modules with an embedded crystal.

SRAM supervisor functions can transform a standard volatile SRAM into a non-volatile type of memory by using the backup power of the RTC. Additional functions like programmable watchdog, an early power-fail warning circuit and the power-on reset/low-voltage detect feature provide support for master MCU operations. The programmable alarm with repeat mode may be used for battery back-up operations.

Battery with crystal option

ST's removable/replaceable SNAPHAT® battery top contains a lithium coin-cell battery and a 32-kHz crystal. It is compatible with all of ST's serial- and parallel-interface real-time clocks in surface-mount SOH-28 and SOH-44 packages.

The SNAPHAT top is designed to be "snapped on" after the SOIC is surface-mounted on the PC board, preventing the battery and crystal from being exposed to the high temperatures of the surface mount process.

To evaluate the battery capacity consumption and lifetime, visit the Real-time clock battery life calculation webpage.
C code examples for interfacing with our serial RTCs are also available.

Featured Products

Real-time clock for demanding wearable devices

M41T62LCF ultra-low power clock

ST’s M41T62LC6F real-time clock is the perfect match for wearable devices when size, weight, and power-efficiency matters.

It offers a very low frequency error at 25 °C which equates to about 5 seconds per month, an ultra-low power consumption of 350 nA in standby, and comes in an ultra-small 1.5 x 3.2 mm package with an embedded crystal oscillator.