Datasheet

 2010 Microchip Technology Inc. Preliminary DS22266A-page 15
MCP7941X
4.2.7 POWER-FAIL TIME-STAMP
The MCP7941X family of RTCC devices feature a
power-fail time-stamp feature. This feature will save
the time at which V
CC crosses the VTRIP voltage. To
use this feature, a V
BAT supply must be present and
the oscillator must also be running.
There are two separate sets of registers that are used
to record this information:
• The first set located at 0x18h through 0x1Bh are
loaded at the time when V
CC fails and the RTCC
operates on the V
BAT. The VBAT (register 0x03h
bit 4) bit is also set at this time.
• The second set of registers, located at 0x1Ch
through 0x1Fh, are loaded at the time when V
CC
is restored and the RTCC switches to V
CC.
The power-fail time-stamp registers are cleared when
the V
BAT bit is cleared in software.