MCP795W20-I/ST View Datasheet(PDF) - Microchip Technology
Part Name
Description
Manufacturer
MCP795W20-I/ST Datasheet PDF : 54 Pages
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MCP795W1X/MCP795W2X
Description:
The MCP795WXX is a low-power Real-Time Clock/
Calendar (RTCC) that uses digital trimming compen-
sation for an accurate clock/calendar, an interrupt
output to support alarms and events, a power sense
circuit that automatically switches to the backup
supply, nonvolatile memory for safe data storage and
several 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
interface, while VCC is between 1.8V and 3.6V, but can
operate down to 1.3V through the backup supply
connected to the VBAT 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 CLKOUT pin can be set
to generate a number of output frequencies.
For versatility, a digital event detect with a
programmable pulse count can identify the 1st, 4th,
16th or 32nd pulse before sending an interrupt. A
second event detect with built-in debounce input filter
was also implemented to support noisy mechanical
switches.
Since many microcontrollers do not have an integrated
Watchdog Timer, this peripheral has been
implemented in the RTCC. For many applications, this
function must be performed outside the microcontroller
for increased robustness.
FIGURE 1-1:
BLOCK DIAGRAM
X1
OSC
X2
CLKOUT Divider
VCC
CLKOUT/
BOOT
VBAT
WD
IRQ
WDT
CS
VSS
EEPROM
ID
SRAM
SPI
TIME-STAMP
EVHS
EVLS
SCK
SDI
SDO
DS22280C-page 2
Preliminary
2011-2012 Microchip Technology Inc.
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