Serial RTCs

Like ST's TIMEKEEPER® NVRAMs, Serial RTCs keep track of day-date-time, even in the absence of power. Instead of the standard asynchronous parallel SRAM interface, Serial RTCs use a serial bus. Our devices are available in two industry standard serial interfaces: I²C (Inter-Integrated Circuit) and SPI (Serial Peripheral Interface).


STMicroelectronics ZEROPOWER products integrate low power SRAMs with a power-fail control circuit and a long-life lithium battery. The power-fail circuit monitors the external power supply voltage. If this falls below a specific threshold it automatically write-protects the SRAM and switches the standby power supply to the internal lithium battery. The advantage is long term data retention with fast READ/WRITE times and unlimited READ/WRITE cycles of standard SRAMs.


STMicroelectronics TIMEKEEPER products add a quartz crystal, very low power oscillator and a clock/calendar circuit to provide real-time data. Advanced TIMEKEEPERs include additional features such as programmable alarms, watchdog timers, system reset outputs and battery low warning flags

TIMEKEEPER Supervisors 

TIMEKEEPER Supervisors convert standard low-power SRAM devices into non-volatile memory. They provide control and battery backup from 1Mbit to 16Mbit external low power SRAM with up to 10 years of data retention, depending on the Supervisor, battery and SRAM type selected.

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