High-Speed Tia Circuits; Key Features - Analog Devices ADuCM356 Reference Manual

Reference Manual

HIGH-SPEED TIA CIRCUITS

The high-speed TIA is intended for measuring wide bandwidth input
signals up to 200 kHz. The output of the high-speed TIA transfers to
the main ADC mux, where the high-speed TIA can be selected as
the ADC input channel. The high-speed TIA is especially designed
for impedance measurements in conjunction with the high-speed
DAC and excitation amplifier. To connect the high-speed TIA to the
external sensor pins, the user must configure the transmit switches
as described in the Tx Switches

KEY FEATURES

To turn on the high-speed TIA, set AFECON, Bit 11 = 1. Clear to
0 to power down the high-speed TIA. The high-speed TIA is off by
default.
The high-speed TIA has programmable flexibility built into its in-
put signal selection, R selection, R
TIA
mode voltage source. The input signal options are as follows:
SE0 input pin from sense electrode of Channel 0 sensor.
►
Table 120. Configuration of R
LOAD
DE0RESCON, Bits[7:0] (DE0) and DE1RESCON, Bits[7:0] (DE1) Setting
0xFF
0x00
0x18
0x38
0x58
0x60
0x68
0x70
0x78
0x80
0x88
0x9
0x21
0x39
0x59
0x61
0x69
0x71
0x79
0x81
0x89
0x12
0x2A
0x4A
0x5A
0x62
0x6A
0x72
0x7A
0x82
0x8A
analog.com
section.
selection, and common-
LOAD
and R of High-Speed TIA When Using DE0 and DE1 Electrodes
TIA
SE1 input pin from sense electrode of Channel 1 sensor.
►
AIN0, AIN1, AIN2, and AIN3/BUF_VREF1V8 input pins.
►
DE0 input pin. This is the Diagnostic Electrode 0 pin (DE0). This
►
pin has its own R and R
LOAD03
DE0RESCON register.
DE1 input pin. This is the Diagnostic Electrode 1 pin (DE1). This
►
pin has its own R and R
LOAD05
DE1RESCON register.
The R options are in the 50 Ω to 160 kΩ.1 kΩ range for the
TIA2_x
DE0 and DE1 inputs. For all other pins, the gain range is 200 Ω to
160 kΩ.
The R option for the SE0 and SE1 channels is a fixed 100 Ω
LOADx
resistor. However, for the DE0 and DE1 input pins, the R
programmable. The R
LOADx
100 Ω.
R and R Value (Ω)
LOAD03 LOAD05
Disconnected
0
0
0
0
0
0
0
0
0
0
10
10
10
10
10
10
10
10
10
10
30
30
30
30
30
30
30
30
30
30
ADuCM356
options configurable via the
TIA2_03
options configurable via the
TIA2_05
LOADx
values are 0 Ω, 10 Ω, 30 Ω, 50 Ω, and
R and R Value
TIA2_03 TIA2_05
Disconnected
50 Ω
100 Ω
200 Ω
1.1 kΩ
5.1 kΩ
10.1 kΩ
20.1 kΩ
40.1 kΩ
80.1 kΩ
160.1 kΩ
50 Ω
100 Ω
190 Ω
1.09 Ω
5.09 kΩ
10.09 kΩ
20.09 kΩ
40.09 kΩ
80.09 kΩ
160.09 kΩ
50 Ω
100 Ω
210 Ω
1.07 kΩ
5.07 kΩ
10.07 kΩ
20.07 kΩ
40.07 kΩ
80.07 kΩ
160.07 kΩ
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