XR10910 Datasheet, PDF (14/19 Pages) Exar Corporation – 16:1 Sensor Interface

XR10910
Inputs and Input Selection
The XR10910 includes 16 differential inputs and a 16:1
differential mux that is controlled by an I²C compatible 2
wire serial interface. The XR10910 is designed to accept 16
differential inputs.
■■ If fewer than 16 differential inputs are required, tie the unused
inputs to GND.
■■ If single ended inputs are required, tie the unused inputs to
1.5V.
The input common mode range of the XR10910 is typically
0.6V to 2.4V when running from a 3.3V supply. The XR10910
offers a very wide gain range. In most cases, the output
voltage swing will be the limiting factor.
When the XR10910 is powered-up, the default input selected
is Channel 1.
Inputs are selected via I²C using one of 16 register addresses
0x10 thru 0x1F. Refer to the Register List in Table 1.
Example: The example below illustrates how to select
Channel 5.
Step 1
0
Master sends start condition
S
Gain Selection
The XR10910 offers 8 selectable fixed gains ranging from
2V/V to 760V/V. When the XR10910 is powered-up, the
default gain is 2V/V.
The gain is selected via I²C using the register address 0x06
followed by another byte of data to select the gain. Refer
to the Register List in Table 1 and the Gain Register list in
Table 3.
Example: The example below illustrates how to select a
gain of 150V/V.
To start communication with the XR10910, repeat steps 1-3
as shown in the Inputs and Input Selection section on page
11.
Step 4
Master sends address of register to access
76543210
00000110
Gain Select register address =
0x06
Step 5
9
XR10910 sends acknowledge
A
Step 2
Master sends XR10910 address with write bit
76543210
01101110
6
7
W
7-bit XR10910 Address = 0x67
Step 3
9
XR10910 sends acknowledge
A
Step 4
Master sends address of register to access
76543210
00010100
Select_Input 5 register address
= 0x14
Step 5
9
XR10910 sends acknowledge
A
Step 6
0
Master sends stop condition
P
White Block = host to XR10910
Red Block = XR10910 to host
Grey Block = Notes
Since the Gain Select register was accessed, the XR10910
is expecting another byte of data from the master to complete
the command. Refer to the “Byte of Parameter” column in
the Register List (Table 1). D0 thru D2 are used to select
the gain. Refer to the Gain Register list in Table 3, 150V/V is
D2 = 1, D1 = 0, and D0 = 0. This translates to a hex code of
0x04, since a full byte of data (8-bits) will be sent.
Step 6
76543210
Master sends gain register data to select G=150 0 0 0 0 0 1 0 0
Gain of 150V/V = 0x04
Step 7
9
XR10910 sends acknowledge
A
Step 8
0
Master sends stop condition
P
White Block = host to XR10910
Red Block = XR10910 to host
Grey Block = Notes
© 2014-2015 Exar Corporation
14 / 19
exar.com/XR10910
Rev 1B