Electronic Design
Real Time Clock Timestamps Power Outage

Real Time Clock Timestamps Power Outage

Microchip is moving into standalone real time clock/calendar chips with its MCP794XX RTCC devices. The chip (Fig. 1) features on-chip memory and automatic battery switch over with time stamping during a power outage. It is accurate to 1 PPM or 86 msec/day. It supports digital trimming with a range of -127 to +127 PPM. There is also a programmable clock output based on Vcc that can be from 1 Hz to 32 KHz. The chips target smart-energy applications like thermostats, power meters, home-appliance, and automotive applications.

The chip uses an industry standard 8-pin pinout with interfacing to a microcontroller via I2C. The low power chip uses less than 700nA to run the clock an it can also operate in 5V systems. The chip has 64 bytes for battery-backed SRAM, 1 Kbits (128 bytes) of EEPROM and a unique 64bit EEPROM ID. The latter can be programmed for EUI-48 and EUI-64 MAC addresses.

Pricing starts at $0.70. The MCP79410 RTCC PICtail Plus Daughter Board (Fig. 2)is priced at $45. The daughter board works with Microchip’s Explorer 16 Development Board, PIC18 Explorer Board, PICkit Serial Analyzer and the XLP 16-bit Development Board.

Check out my video interview with Microchip on Engineering TV.

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