MCP7952X/MCP7951X
Description:
The MCP795XX is a low-power Real-Time Clock/
Calendar (RTCC) that uses digital trimming compen-
sation for an accurate clock/calendar, an interrupt out-
put to support alarms and events, a power sense
circuit that automatically switches to the backup sup-
ply, nonvolatile memory for safe data storage and sev-
eral enhanced features that support system
requirements.
Along with a low-cost 32,768 kHz crystal, this RTCC
tracks time using several internal registers and then
communicates the data over a 5 MHz SPI bus that is
fast enough to support a programmable millisecond
alarm.
The device is fully accessible through the serial inter-
face, while V
CC
is between 1.8V and 3.6V, but can
operate down to 1.3V through the backup supply con-
nected to the V
BAT
input for timekeeping and SRAM
retention only.
As part of the power sense circuit, a time saver
function is implemented to store the time when main
power is lost and again, when power is restored to log
the duration of a power failure.
Along with the on-board serial EEPROM and battery-
backed SRAM, a 128-bit protected space is available
for a unique ID. This space can be ordered
preprogrammed with a MAC address, or blank for the
user to program.
This clock/calendar automatically adjusts for months
with fewer than 31 days including corrections for leap
years. The clock operates in either 24-hour or 12-hour
format with AM/PM indicator and settable alarm(s).
Using the external crystal, the MFP pin can be set to
generate a number of output frequencies.
FIGURE 1-1:
BLOCK DIAGRAM
X1
CLKOUT Divider
OSC
X2
V
BAT
SWITCHOVER
V
CC
MFP
V
BAT
EEPROM
SCK
ID
SO
CS
ALARMS
SRAM
SPI
TIME-STAMP
V
SS
SI
DS22300A-page 2
Preliminary
2012 Microchip Technology Inc.
MAS [ MICRO ANALOG SYSTEMS ]
