MCP3421EV Microchip Technology, MCP3421EV Datasheet - Page 17

• Manufacturer Part Number: MCP3421EV
• Description: BOARD EVAL FOR MCP3421 SOT23-6
• Manufacturer: Microchip Technology

Specifications of MCP3421EV

• Design Resources: MCP3421EV Gerber Files
• Number Of Adc's: 1
• Number Of Bits: 18
• Sampling Rate (per Second): 4
• Data Interface: Serial
• Inputs Per Adc: 1 Single Ended
• Input Range: ±2.5 V
• Voltage Supply Source: Single Supply
• Operating Temperature: -40°C ~ 125°C
• Utilized Ic / Part: MCP3421
• Silicon Manufacturer: Microchip
• Application Sub Type: ADC
• Kit Application Type: Data Converter
• Silicon Core Number: MCP3421
• Kit Contents: Board
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Not applicable / Not applicable

If the configuration byte is read repeatedly by clocking
continuously after reading the data bytes (i.e., after the
5th byte in the 18-bit conversion mode), the state of the
RDY bit indicates whether the device is ready with new
conversion result. When the Master finds the RDY bit is
cleared, it can send a not-acknowledge (NAK) bit and
a stop bit to exit the current read operation and send a
new read command for the latest conversion data.
Once the conversion data has been read, the ready bit
toggles to ‘1’ until the next new conversion data is
ready. The conversion data in the output register is
overwritten every time a new conversion is completed.
Figure 5-3
reading the conversion data. The user can rewrite the
configuration byte any time for a new setting.
Table 5-1
configuration bit operation.
TABLE 5-1:
TABLE 5-2:
© 2009 Microchip Technology Inc.
R/W O/C RDY
R/W O/C RDY
0
0
0
0
1
1
1
1
0
0
1
1
0
0
1
1
and
and
0
1
0
1
0
1
0
1
Table 5-2
Figure 5-4
WRITE CONFIGURATION BITS
READ CONFIGURATION BITS
No effect if all other bits remain
the same - operation continues
with the previous settings
Initiate One-Shot Conversion
Initiate Continuous Conversion
Initiate Continuous Conversion
New conversion result in One-
Shot conversion mode has just
been read. The RDY bit remains
low until set by a new write
command.
One-Shot Conversion is in
progress. The conversion result
is not updated yet. The RDY bit
stays high until the current
conversion is completed.
New conversion result in
Continuous Conversion mode
has just been read. The RDY bit
changes to high after reading the
conversion data.
The conversion result in
Continuous Conversion mode
was already read. The next new
conversion data is not ready. The
RDY bit stays high until a new
conversion is completed.
show the examples of the
show the examples of
Operation
Operation
5.3
The
(microcontroller) through a serial I
Circuit) interface and support standard (100 kbits/sec),
fast (400 kbits/sec) and high-speed (3.4 Mbits/sec)
modes.
The serial I
communication protocol using open-drain SCL and
SDA lines.
The device can only be addressed as a slave. Once
addressed, it can receive configuration bits with a write
command or transmit the latest conversion results with
a read command. The serial clock pin (SCL) is an input
only and the serial data pin (SDA) is bidirectional. The
Master starts communication by sending a START bit
and terminates the communication by sending a STOP
bit. In read mode, the device releases the SDA line
after receiving NAK and STOP bits.
An example of a hardware connection diagram is
shown in
characteristic is described in Section 5.6 “I
Characteristics”.
5.3.1
The first byte after the START bit is always the address
byte of the device, which includes the device code
(4 bits), address bits (3 bits), and R/W bit. The device
code of the MCP3421 is 1101, which is programmed at
the factory. The device code is followed by three
address bits (A2, A1, A0) which are also programmed
at the factory. The three address bits allow up to eight
MCP3421 devices on the same data bus line.
The (R/W) bit determines if the Master device wants to
read the conversion data or write to the Configuration
register. If the (R/W) bit is set (read mode), the device
outputs the conversion data in the following clocks. If
the (R/W) bit is cleared (write mode), the device
expects a configuration byte in the following clocks.
When the device receives the correct address byte, it
outputs an acknowledge bit after the R/W bit.
Figure 5-1
Figure 5-4
bits and read the conversion results.
Note:
device
I
2
shows the address byte.
show how to write the configuration register
C Serial Communications
Figure
The
recommended for V
I
2
2
C DEVICE ADDRESSING
C is a bidirectional 2-wire data bus
6-1. More details of the I
communicates
High-Speed
MCP3421
DD
2
less than 2.7V.
mode
C (Inter-Integrated
Figure 5-2
DS22003E-page 17
with
is
2
2
through
C Bus
Master
C bus
not