Chandler, Ariz., USA: A family of standalone real-time clock/calendar (RTCC) devices developed by Microchip feature a 10MHz SPI and nonvolatile memory. The overall goal of the MCP795WXX/BXX RTCCs is to reduce component counts and costs for smart-energy products, home appliances, automotive dashboard controls, office equipment, and consumer electronics.
The devices’ 10MHz SPI supports very fast data access, resulting in longer MCU sleep and power-down modes, as well as less power draw from the battery. Other low-power features include two event-detect inputs that draw minimal current in the RTCC device, but wake the MCU in the event of a switch press or system tampering.
The devices also include three types of nonvolatile memory: EEPROM, SRAM, and a Unique ID. The latter can be ordered blank, or with a pre-programmed MAC address as a standard product, to further reduce component counts and lower costs associated with serialised programming.
In addition to the automatic battery switchover for backup power, a power-fail timestamp logs the time and duration of any power failure. For accurate timekeeping over a broad temperature range, the devices feature a wide digital-trimming range that compensates for crystal frequency drift over temperature. In designs that use a second low-frequency crystal, a boot-clock option provides a 32kHz clock at power-up, reducing the need for a second crystal.
The MCP795XX SPI RTCC PICtail Plus daughterboard (AC164147), available February 2012, will be compatible with Microchip’s Explorer 16 Development Board (DM240001) and PIC18 Explorer Board (DM183032).