M41ST87Y and M41ST87W are 5.0V and 3.3/3.0V secure serial RTC and NVRAM supervisors with tamper detection and 128 bytes of clearable NVRAM. They support various operating voltages, have a 400kHz I2C bus, and feature automatic switchover and deselect circuitry. The products have multiple features, including NVRAM supervisor, counters, programmable alarm and interrupt function, programmable watchdog timer, unique electronic serial number, and low battery supply current.