Introduction To The Ads704X-5Xevm; Analog Inputs - Texas Instruments ADS7042EVM-PDK User Manual

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2 Introduction to the ADS704X-5XEVM

Each ADS704X-5XEVM board includes the peripheral analog circuits and components required to extract
optimum performance from each ADC signal chain. Important portions of the EVM are highlighted in
2-1, and described in the subsequent sections.

2.1 Analog Inputs

As shown in Figure 2-1, the ADS704X-5XEVM has two analog input paths: a single-ended input path highlighted
in red, and a differential input path highlighted in green. SMA connectors and headers are included on each path
to connect external signals. These signals feed into a driver amplifier and then to one of two ADC footprints,
where the digital output is supplied to the PHI via J4.
2.1.1 Single-Ended Input Path
The single-ended input path consists of an inverting driver amplifier, an RC circuit, and two ADC footprints.
Figure 2-2 shows the single-ended input path schematic.
R37
DNP
C12
DNP
R36
1.00k
OPA_VDD
5
R35
J1
1.00k
1 4
R42
VBIAS 3
100
AGND
C14
R43
10nF
JP1 0
AGND
Figure 2-2. Single-Ended Input Path on the ADS704X-5XEVM
SBAU382 – NOVEMBER 2021
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Figure 2-1. Important Subsections of the ADS704X-5XEVM
0
100nF
C10
100nF
U3
R14
AGND
16.0
1 U3_AINP 6
AINP
OPA836IDBVR
C11
U6
300pF
AINM U3_AINM
5
AINM
R38
OPA_VSS
16.0
R40 8
GND
0
ADS7042IDCUR
AGND
Replace R43 and R44 with 100nF
capacitors when OPA_VSS ≠ AGND
Copyright © 2021 Texas Instruments Incorporated
AVDD EVM_DVDD
R11 R12
0 0
C8 C9
1µF 1µF
AGND AGND
7 U3_AVDD
AVDD
U3_DVDD
1
DVDD
U3_SCLK R18 49.9 SCLK_AB
2
SCLK
3 U3_SDO R19 49.9 SDO_A
SDO
4 U3_CS R20 49.9 CS_A
CS
ADS7042EVM-PDK, ADS7049-Q1EVM-PDK, and ADS7057EVM-PDK
Introduction to the ADS704X-5XEVM
Figure
U8
U3_AINP 7 6 U3_AVDD
AINP AVDD
U3_DVDD
4
DVDD
U3_AINM
8
AINM DNP
U3_SCLK
3
SCLK
2 U3_SDO
SDO
5 1 U3_CS
GND CS
ADS7042IRUGR
AGND
Evaluation Module
5