The MCP795WXX 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 MCP795WXX supports SPI
communications up to 5 MHz.
The MCP795WXX 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 MCP795WXX features 128 bits of EEPROM
which is only writable after an unlock sequence,
making it ideal for storing a unique ID or other critical
The MCP795WX1 and MCP795WX2 are
preprogrammed with EUI-48 and EUI-64 addresses,
respectively. Custom programming is also available.
Two event detect modules are included on the
MCP795WXX. The high-speed event detect module
will generate an interrupt after a programmable
number of pulses have been detected. The low-speed
event detect module can be used to debounce
mechanical switches and includes a selectable
The MCP795WXX also features an integrated
Watchdog Timer peripheral. This allows applications to
improve system robustness by moving this
functionality outside of the microcontroller.
The MCP795WXX has versatile output options. There
is a dedicated pin for outputting a selectable frequency
square wave or for use as a general purpose output.
Additionally, the alarms can be assigned to either the
Watchdog Timer interrupt output or the event detect
TYPICAL APPLICATION SCHEMATIC
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