Microchip Technology MCP3422EV Hoja De Datos
MCP3422/3/4
DS22088C-page 32
© 2009 Microchip Technology Inc.
6.1.4
DEVICE CONNECTION TEST
The user can test the presence of the MCP3422/3/4 on
the I
the I
2
C bus line without performing an input data
conversion. This test can be achieved by checking an
acknowledge response from the MCP3422/3/4 after
sending a read or write command. Here is an example
using
acknowledge response from the MCP3422/3/4 after
sending a read or write command. Here is an example
using
a.
Set the R/W bit “HIGH” in the address byte.
b.
Check the ACK pulse after sending the address
byte.
byte.
If the device acknowledges (ACK = 0), then the
device is connected, otherwise it is not
connected.
device is connected, otherwise it is not
connected.
c.
Send STOP or START bit.
FIGURE 6-3:
I
2
C Bus Connection Test.
6.1.5
DIFFERENTIAL AND SINGLE-
ENDED CONFIGURATION
ENDED CONFIGURATION
shows typical connection examples for
differential and single-ended inputs. Differential input
signals can be connected to the CHn+ and CHn- input
pins, where n = the channel number (1, 2, 3, or 4). For
the single-ended input, the input signal is applied to one
of the input pins (typically connected to the CHn+ pin)
while the other input pin (typically CHn- pin) is
grounded. All device characteristics hold for the single-
ended configuration, but this configuration loses one bit
resolution because the input can only stand in positive
half scale. Refer to Section 1.0 “Electrical Character-
istics”.
signals can be connected to the CHn+ and CHn- input
pins, where n = the channel number (1, 2, 3, or 4). For
the single-ended input, the input signal is applied to one
of the input pins (typically connected to the CHn+ pin)
while the other input pin (typically CHn- pin) is
grounded. All device characteristics hold for the single-
ended configuration, but this configuration loses one bit
resolution because the input can only stand in positive
half scale. Refer to Section 1.0 “Electrical Character-
istics”.
FIGURE 6-4:
Differential and Single-
Ended Input Connections.
1
2
3
4
5
6
7
8
9
SCL
SDA
1
1
0
1 A2 A1 A0 1
Start
Bit
Address Byte
Address bits
Device bits
R/W
Stop
Bit
ACK
Response
MCP342X
(a) Differential Input Signal Connection:
CHn+
CHn-
Input Signal
(b) Single-ended Input Signal Connection:
CHn+
CHn-
Input Signal
Sensor
Sensor
Excitation
Excitation
R
1
R
2
MCP342X
MCP342X