IC-TW3 Datasheet, PDF (14/24 Pages) IC-Haus GmbH – SENSOR SIGNAL CONDITIONER WITH TEMPERATURE COMPENSATION AND LINE DRIVER

iC-TW3 SENSOR SIGNAL CONDITIONER WITH
TEMPERATURE COMPENSATION AND LINE DRIVER
A/B SIGNAL PATH
Rev B1, Page 14/24
iC-TW3 incorporates two analog gain paths called
channel A and B, respectively. Gain and offset of both
paths are independently controlled and temperature
compensated. Figure 4 depicts a diagram of a single
signal path, Table 8 below summarizes gain and offset
characteristics.
PINA/PINB
NINA/NINB
VDD
ENSIGAB
SINGLEIN
VDD/2
COFSA/B(5:0)
+
Input
+
-
CGAINA/B(2:0)
+
FOFSA/B(7:0)
FILTER(1:0)
dynamic
FGAINA/B(7:0)
output
OGAIN(1:0)
AO/BO
NAO/NBO
Figure 4: The A/B signal path
Gain range
Gain step
Offset range input
referred
Offset step input referred
Input Amplifier
0..36 dB
6.0 dB
1.24 V
gaininput
Dynamic Amplifier
-2..18.4 dB
0.08 dB
0.25 V
gaininput
40 mV
2 mV
gaininput
gaininput
gain_of _input_amplifier _in_dB
gain_input = 10
20
Output Amplifier
-3 dB, 0 dB, 6 dB
Composite
-5..60 dB
1.49 V
gaininput
Table 8: Overview of gain and offset characteristics
Single ended signals
Single ended input functionality is provided by con-
necting the negative input terminal (pins NINA and
NINB) to an internally generated voltage of V_DD/2. This
is enabled by setting the control bit SINGLEIN to 1. Al-
ternatively, an externally generated reference voltage
may be applied to the negative input terminals.
SINGLEIN
Adr 0x01; Bit 5
R/W
Code
Function
0
A and B inputs are differential (default)
1
A and B inputs are single ended
or damaged sensor connections. Any input terminal
left unconnected is pulled to V_DD and triggers a sensor
error condition err_sig.
ENSIGAB
Code
0
1
Adr 0x03; Bit 0
R/W
Function
Pull-up resistors disconnected and error reporting
disabled (default)
Pull-up resistors and error reporting active on A/B
inputs
Table 10: Input signal error detection control
Table 9: Single ended input functionality
Input error detection
Weak input pull-up resistors are enabled by setting
control bit ENSIGAB to 1. The resistors are at min-
imum 2.0 MΩ. When driving the input with a high
impedance source it might be necessary to disable
the pull-up resistors to avoid excessive signal distor-
tion. The pull-up resistors are used to sense floating
Gain and offset
Registers CGAINA(2:0) and CGAINB(2:0) are used to
set the coarse gain. Coarse gain is static and it is not
changed by the temperature or automatic compensa-
tion algorithm.
The highest legal value for CGAINA(2:0) and
CGAINB(2:0) is 6. Equivalently registers COFSA(5:0)
and COFSB(5:0) are used to control the static off-