MCP7940NT-I/MNY Microchip Technology, MCP7940NT-I/MNY Datasheet - Page 11

• Manufacturer Part Number: MCP7940NT-I/MNY
• Description: Real Time Clock I2C GP RTCC 64B SRAM
• Manufacturer: Microchip Technology
• Series: -r
• Type: Clock/Calendarr

Specifications of MCP7940NT-I/MNY

• Features: Alarm, Leap Year, SRAM
• Memory Size: 64B
• Time Format: HH:MM:SS (12/24 hr)
• Date Format: YY-MM-DD-dd
• Interface: I²C
• Voltage - Supply: 1.8 V ~ 5.5 V
• Voltage - Supply, Battery: 1.3 V ~ 5.5 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-WFDFN Exposed Pad
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

• ALMxIF: This is the Alarm Interrupt Fag. This bit is
• ALMxC2:0: These Configuration bits determine
• The 12/24-hour bits 0xCh.6 and 0x13h.6 are cop-
0x18h-0x1Bh are used for the timesaver function.
These registers are loaded at the time when V
and the RTCC operates on the V
also set at this time. These registers are cleared when
the V
0x1Ch-0x1Fh are used for the timesaver function.
These registers are loaded at the time when V
restored and the RTCC switches to V
registers are cleared when the V
software.
 2011 Microchip Technology Inc.
000 –
001 –
010 –
011 –
100
101
110
111
set in hardware if the alarm was triggered. The bit
is cleared in software.
the alarm match. The logic will trigger the alarm
based on one of the following match conditions:
ies of the bit in 0x02h.6. The bits are read-only.
Note:
BAT
– Date
– RESERVED
– RESERVED
– Seconds, Minutes, Hour, Day, Date,
bit is cleared in software.
It is strongly recommended that the
timesaver function only be used when the
oscillator is running. This will ensure
accurate functionality.
Seconds match
Minutes match
Hours match (takes into account 12/24
hour)
Matches the current day, interrupt at
12.00.00 a.m. Example: 12 midnight on
Month
BAT
BAT
. The V
bit is cleared in
DD
BAT
. These
CC
CC
bit is
fails
is
4.2
4.2.1
The MCP7940N utilizes digital calibration to correct for
inaccuracies of the input clock source (either external
or crystal). Calibration is enabled by setting the value
of the Calibration register at address 08H. Calibration
is achieved by adding or subtracting a number of input
clock cycles per minute in order to achieve ppm level
adjustments in the internal timing function of the
MCP7940N.
The MSB of the Calibration register is the sign bit, with
a ‘1’ indicating subtraction and a ‘0’ indicating addition.
The remaining seven bits in the register indicate the
number of input clock cycles (multiplied by two) that
are subtracted or added per minute to the internal
timing function.
The internal timing function can be monitored using
the MFP open-drain output pin by setting bit [6]
(SQWE) and bits [2:0] (RS2, RS1, RS0) of the control
register at address 07H. Note that the MFP output
waveform is disabled when the MCP7940N is running
in V
two methods that can be used to observe the internal
timing function of the MCP7940N:
A. RS2 BIT SET TO ‘0’
With the RS2 bit set to ‘0’, the RS1 and RS0 bits
enable the following internal timing signals to be
output on the MFP pin:
The frequencies listed in the table presume an input
clock source of exactly 32.768 kHz. In terms of the
equivalent number of input clock cycles, the table
becomes:
With regards to the calibration function, the Calibration
register setting has no impact upon the MFP output
clock signal when bits RS1 and RS0 are set to ‘11’.
The setting of the Calibration register to a non-zero
value (i.e., values other than 00H or 80H) enables the
calibration function which can be observed on the
MFP output pin. The calibration function can be
expressed in terms of the number of input clock cycles
added/subtracted from the internal timing function.
RS2
RS2
BAT
0
0
0
0
0
0
0
0
mode. With the SQWE bit set to ‘1’, there are
FEATURES
CALIBRATION
RS1
RS1
0
0
1
1
0
0
1
1
RS0
RS0
0
1
0
1
0
1
0
1
MCP7940N
Output Signal
Output Signal
32.768 kHz
DS25010A-page 11
4.096 kHz
8.192 kHz
32768
1 Hz
8
4
1