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.
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Real-time clock for demanding wearable devices
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.
- M41T82 Serial I²C bus real-time clock (RTC) with battery switchover
- M41T0 Serial real-time clock (RTC)
- M41T93 Serial SPI bus real-time clock (RTC) with battery switchover
- M41T66 Serial real-time clock (RTC) with alarm
- M41T64 Low-power serial real-time clock (RTC) with alarm
- M41T83 Serial I²C bus real-time clock (RTC) with battery switchover
- M41ST87W 5.0 V, 3.3/3.0 V secure real-time clock , NVRAM supervisor with tamper detection and 128 bytes of clearable NVRAM
- M41T81 Serial real-time clock (RTC) with alarm
- M41T94 Serial real-time clock (RTC) with 44 bytes NVRAM and reset
- M41T56 Serial real-time clock (RTC) with 56 bytes NVRAM
- M41T00CAP Serial real-time clock (RTC) with integral backup battery and crystal
- M41T80 Serial real-time clock (RTC) with alarm
- M41T00 Serial real-time clock (RTC)
- M41T00AUD Serial real-time clock (RTC) with audio
- M41T11 Serial real-time clock (RTC) with 56 bytes of NVRAM
- M41ST85W 3.0/3.3 V I²C combination real-time clock, NVRAM supervisor and microprocessor supervisor
- M41T81S Serial real-time clock (RTC) with alarm
- M41T60 Low power serial real-time clock (RTC)
- M41T00S Serial real-time clock (RTC)
- M41T01 Serial real-time clock (RTC) with built-in battery switchover circuit
- M41T62 Low-power serial real-time clock (RTC) with alarm
- M41T65 Low-power serial real-time clock (RTC) with alarm
