MCP3422 datasheet(32/58 Pages) MICROCHIP

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MCP3422/3/4

DS22088C-page 32

6.1.4

DEVICE CONNECTION TEST

The user can test the presence of the MCP3422/3/4 on

the I2C 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 Figure 6-3:

Set the R/W bit “HIGH” in the address byte.

Check the ACK pulse after sending the address

byte.

If the device acknowledges (ACK = 0), then the

device

connected,

otherwise

not

connected.

Send STOP or START bit.

FIGURE 6-3:

I2C Bus Connection Test.

6.1.5

DIFFERENTIAL AND SINGLE-

ENDED CONFIGURATION

Figure 6-4 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”.

FIGURE 6-4:

Differential and Single-

Ended Input Connections.

SCL

SDA

1A2 A1 A0 1

Start

Bit

Address Byte

Address bits

Device bits

R/W

Stop

Bit

Response

MCP342X

(a) Differential Input Signal Connection:

CHn+

CHn-

Input Signal

(b) Single-ended Input Signal Connection:

CHn+

CHn-

Input Signal

Sensor

Excitation

MCP342X

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