描述 Description

The MCP795XX Real-Time Clock/Calendar (RTCC)

tracks time using internal counters for hours, minutes,

seconds, hundredth of seconds, days, months, years

and day of week. Alarms can be configured on all

counters up to and including months. For usage and

configuration, the MCP795XX supports SPI

communications up to 5 MHz.

The MCP795XX is designed to operate using a

32.768 kHz tuning fork crystal with external crystal

load capacitors. On-chip digital trimming can be used

to adjust for frequency variance caused by crystal

tolerance and temperature.

SRAM and timekeeping circuitry are powered from the

backup supply when main power is lost, allowing the

device to maintain accurate time and the SRAM

contents. The times when the device switches over to

the backup supply and when primary power returns

are both logged by the power-fail timestamp.

The MCP795XX features 128 bits of EEPROM which

is only writable after an unlock sequence, making it

ideal for storing a unique ID or other critical

information. The MCP795X1 and MCP795X2 are

preprogrammed with EUI-48 and EUI-64 addresses,

respectively. Custom programming is also available.

The MCP795XX has a shared pin for outputting a

selectable frequency square wave or alarm signals.

Timekeeping Features

? Real-Time Clock/Calendar (RTCC):

- Hours, minutes, seconds, hundredth of

seconds, day of week, date, month, year

- Leap year compensated to 2399

- 12/24-hour modes

? Oscillator for 32.768 kHz Crystals:

- Optimized for 6-9 pF crystals

? On-Chip Digital Trimming/Calibration:

- ±1 ppm resolution

- ±259 ppm range

? Dual Programmable Alarms

? Clock Output Function with Selectable Frequency

? Power-Fail Timestamp:

- Time logged on switchover to and from Battery mode

Low-Power Features

? Wide Voltage Range:

- Operating voltage range of 1.8V to 3.6V

- Backup voltage range of 1.3V to 3.6V

? Low Typical Timekeeping Current:

- Operating from VCC: 1.2 μA at 3.0V

- Operating from VBAT: 1.0 μA at 3.0V

? Automatic Switchover to Battery Backup