MCP7940N-I/ST Microchip Technology, MCP7940N-I/ST Datasheet - Page 8
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MCP7940N-I/ST
Manufacturer Part Number
MCP7940N-I/ST
Description
Real Time Clock I2C GP RTCC 64B SRAM
Manufacturer
Microchip Technology
Series
-r
Type
Clock/Calendarr
Datasheet
1.MCP7940N-IMS.pdf
(36 pages)
Specifications of MCP7940N-I/ST
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-TSSOP (0.173", 4.40mm Width)
Lead Free Status / RoHS Status
Lead free / RoHS Compliant
MCP7940N
FIGURE 3-2:
3.1.2
A control byte is the first byte received following the
Start condition from the master device
The control byte for accessing the SRAM and RTCC
registers are set to ‘1101111’. The RTCC registers and
the SRAM share the same address space.
The last bit of the control byte defines the operation to
be performed. When set to a ‘1’ a read operation is
selected, and when set to a ‘0’ a write operation is
selected. The next byte received defines the address of
FIGURE 3-3:
DS25010A-page 8
SCL
SDA
DEVICE ADDRESSING AND OPERATION
1
Transmitter must release the SDA line at this point
allowing the Receiver to pull the SDA line low to
acknowledge the previous eight bits of data.
X = Don’t Care
ACKNOWLEDGE TIMING
ADDRESS SEQUENCE BIT ASSIGNMENTS
2
1
SRAM RTCC CONTROL BYTE
CONTROL
CODE
1
3
Data from transmitter
0
4
1
(Figure
1
5
1
3-2).
1
6
R/W
7
Acknowledge
the data byte
transferred first, followed by the Least Significant bits
(LSb).
Following the Start condition, the MCP7940N monitors
the SDA bus, checking the device type identifier being
transmitted. Upon receiving an ‘1101111’ code, the
slave device outputs an Acknowledge signal on the
SDA line. Depending on the state of the R/W bit, the
MCP7940N will select a read or write operation.
8
X
Bit
•
9
ADDRESS BYTE
•
1
(Figure
•
Receiver must release the SDA line at this point
so the Transmitter can continue sending data.
Data from transmitter
•
2
3-3). The upper address bits are
•
2011 Microchip Technology Inc.
•
3
A
0