Texas Instruments ADS7042EVM-PDK User manual

User’s Guide
ADS7042EVM-PDK, ADS7049-Q1EVM-PDK, and
ADS7057EVM-PDK Evaluation Module
ABSTRACT
This user's guide describes the characteristics, operation, and use of the ADS7042EVM-PDK, ADS7049-
Q1EVM-PDK, and ADS7057EVM-PDK evaluation modules (EVM), referred to collectively as the
ADS704X-5XEVM-PDK. Each kit functions as an evaluation platform for two different low-power, small-size,
general-purpose successive approximation register (SAR) analog-to-digital converters (ADCs). These ADCs
include the 12-bit, 1-MSPS, single-ended input ADS7042, the 12-bit, 2-MSPS, single-ended ADS7049-Q1, the
12-bit, 3-MSPS, differential input ADS7047, and the 14-bit, 2.5-MSPS, differential input ADS7057. Moreover,
unique EVM design enables evaluation of the entire family of ADS704x and ADS705x devices through
minor modifications. Finally, this EVM platform eases device analysis using hardware, software, and computer
connectivity through the universal serial bus (USB) interface.
This user's guide includes complete circuit descriptions, schematic diagrams, and a bill of materials. Throughout
this document, the abbreviation EVM and the term evaluation module are synonymous with any EVM
(ADS7042EVM-PDK, ADS7049-Q1EVM-PDK, or ADS7057EVM-PDK), unless otherwise noted.
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Table of Contents
1 ADS704X-5XEVM-PDK Overview...........................................................................................................................................3
2 Introduction to the ADS704X-5XEVM....................................................................................................................................5
2.1 Analog Inputs..................................................................................................................................................................... 5
2.2 Power Supplies.................................................................................................................................................................. 7
2.3 Digital Interface and Communication................................................................................................................................. 8
2.4 I2C Bus for Onboard EEPROM.......................................................................................................................................... 9
3 ADS704X-5XEVM Software Installation.............................................................................................................................. 10
4 EVM Operation...................................................................................................................................................................... 13
4.1 Connecting the Hardware................................................................................................................................................ 13
4.2 EVM GUI Global Settings for ADC Control...................................................................................................................... 14
4.3 Time Domain Display....................................................................................................................................................... 15
4.4 Spectral Analysis..............................................................................................................................................................16
4.5 Histogram Analysis.......................................................................................................................................................... 17
4.6 Updating EEPROM After ADC Replacement...................................................................................................................17
5 Bill of Materials, Layout, and Schematic............................................................................................................................ 19
5.1 Bill of Materials.................................................................................................................................................................19
5.2 Layout.............................................................................................................................................................................. 21
5.3 Schematic........................................................................................................................................................................ 23
Trademarks
LabVIEW™ is a trademark of National Instruments.
Microsoft® and Windows® are registered trademarks of Microsoft Corporation.
All trademarks are the property of their respective owners.
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1 ADS704X-5XEVM-PDK Overview
The ADS704X-5XEVM-PDK is a platform for evaluating the performance of the ADS704x and ADS705x family of
ADCs. The ADS704X-5XEVM-PDK includes the following features:
• ADS704X-5XEVM for diagnostic testing and accurate performance evaluation of each ADC on the board
• USB powered—no external power supply is required
• A precision host interface (PHI) controller that provides a convenient communication interface to each ADC
over USB 2.0 (or higher) for power delivery as well as digital input and output
• Microsoft® Windows® 8 and Windows® 10 operating systems
• Easy-to-use evaluation software for 64-bit Microsoft® Windows®
• A software suite that includes a graphical user interface (GUI) and tools for data capture, histogram analysis,
and spectral analysis. This suite also has a provision for exporting data to a text file for post-processing
The PHI board primarily serves three functions:
• Provides a communication interface from the EVM to the computer through a USB port
• Provides the digital input and output signals necessary to communicate with each ADC
• Supplies power to all active circuitry on the ADS704X-5XEVM board
Each ADS704X-5XEVM board includes the peripheral analog circuits and components required to extract
optimum performance from the ADC. Moreover, each ADS704X-5XEVM includes two complete ADC signal
chains: one that supports a single-ended input ADC (see Section 2.1.1), and another that supports a differential
input ADC (see Section 2.1.2). Table 1-1 defines which ADCs are populated by default on each EVM.
Table 1-1. Default ADCs Populated on Each EVM Variant
EVM Name Single-Ended ADC (U3) Differential ADC (U5)
ADS7042EVM-PDK ADS7042 ADS7057
ADS7049-Q1EVM-PDK ADS7049-Q1 ADS7047
ADS7057EVM-PDK ADS7042 ADS7057
Additionally, the ADS704X-5XEVM includes the following features:
• External signal source from subminiature version A (SMA) connectors or header pins
• Option to use external power supplies
• Serial interface header for easy connection to the PHI controller
• Pin connections to monitor digital signals with a logic analyzer
• Two ultra-low noise, low-dropout (LDO) regulators for excellent single-supply regulation of all analog circuits
• Accommodates all package options for 14 different ADCs using four different device footprints, as per Table
1-2
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Table 1-2. ADCs Supported by the ADS704X-5XEVM
Supported ADC Populated on EVM? Input Type Package Options (Designator)
ADS7040 n/a Single-ended X2QFN (U8), VSSOP (U3)
ADS7041 n/a Single-ended X2QFN (U8), VSSOP (U3)
ADS7042 ADS7042EVM-PDK,
ADS7057EVM-PDK Single-ended X2QFN (U8), VSSOP (U3)
ADS7043 n/a Pseudo-differential X2QFN (U8), VSSOP (U3)
ADS7044 n/a Differential X2QFN (U5), VSSOP (U9)
ADS7046 n/a Single-ended X2QFN (U8)
ADS7047 ADS7049-Q1EVM-PDK Differential X2QFN (U5)
ADS7052 n/a Single-ended X2QFN (U8)
ADS7054 n/a Differential X2QFN (U5)
ADS7056 n/a Single-ended X2QFN (U8)
ADS7057 ADS7042EVM-PDK,
ADS7057EVM-PDK Differential X2QFN (U5)
ADS7029-Q1 n/a Single-ended VSSOP (U3)
ADS7039-Q1 n/a Single-ended VSSOP (U3)
ADS7049-Q1 ADS7049-Q1EVM-PDK Single-ended VSSOP (U3)
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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 Figure
2-1, and described in the subsequent sections.
Figure 2-1. Important Subsections of the ADS704X-5XEVM
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.
1
2
3
4
5
6
OPA836IDBVR
U6
EVM_DVDD
AGND
0
R12
0
R11
49.9R18
49.9R20
49.9R19 SDO_A
SCLK_AB
CS_A
AGND
AGND
AVDD
OPA_VDD
OPA_VSS
0R37
DNP
AGND
JP1
AGND
U3_AINM
U3_AVDD
U3_DVDD
U3_SCLK
U3_SDO
U3_CS
U3_AVDD
U3_DVDD
U3_SCLK
U3_SDO
U3_CS
U3_AINP
U3_AINM
AGND
U3_AINP
0
R40
AINM
1.00k
R36
1.00k
R35
CS 4
SDO 3
SCLK 2
DVDD 1
GND
8
AVDD 7 AINP
6
AINM
5
ADS7042IDCUR
U3
AGND
100
R42
VBIAS
CS 1
SDO 2
SCLK 3
DVDD 4
GND
5
AVDD 6 AINP
7
AINM
8
ADS7042IRUGR
U8
DNP
1
2
3 4 5
J1
100nFC12DNP
100nF
C10
10nF
C14
1µF
C8
1µF
C9
16.0
R14
16.0
R38
300pF
C11
Replace R43 and R44 with 100nF
capacitors when OPA_VSS ≠ AGND
0
R43
Figure 2-2. Single-Ended Input Path on the ADS704X-5XEVM
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Signals connected to the single-ended input path are applied to an inverting amplifier whose common-mode
voltage is set by VBIAS. The output of the amplifier connects to an RC filter (R14, R38, and C11) that then
connects to the ADC input. A compensation capacitor can be added to the amplifier feedback loop via C12, but
is not required for good performance. The amplifier power supplies are connected by default to the OPA_VDD
and OPA_VSS supplies. Section 2.2 explains how to modify the EVM to use external supplies. If desired, the
amplifier can be bypassed by populating R37 with a 0-Ω resistor and removing R14 and R35.
Figure 2-2 also depicts all connections to the ADC (U3). Each power-supply connection has a 1-μF decoupling
capacitor. The supply connections also have a series 0-Ω resistor that can be removed for the purpose
of making external current measurements. Moreover, each digital input has a 49.9-Ω series resistor. These
resistors smooth the edges of the digital signals to minimize overshoot and ringing.
Finally, Figure 2-2 identifies a do-not-populate (DNP) component in U8. This ADC footprint is on the bottom
of the board and can be used to evaluate any single-ended ADC in an X2QFN package listed in Table 1-2.
However, ensure that any device in U3 is cleanly removed before soldering a device in U8. Section 4.6 explains
how to use the ADS704X-5XEVM GUI to update the EEPROM when the ADC is replaced.
2.1.2 Differential Input Path
The differential input path consists of a differential driver amplifier, an RC circuit, and two ADC footprints. Figure
2-3 shows the differential input path schematic.
AGND
VBIAS
49.9R15
49.9R17
49.9R16 SDO_B
SCLK_AB
CS_B
V+
8V- 4
OPA2836QDGKRQ1
U7C
AGND
16.0
R25
16.0
R27
300pF
C17
1.00k
R23
1.00k
R24
1.00k
R29
1.00k
R30
AGND
OPA_VSS
EVM_DVDD
AGND
0
R22
0
R21
AGND
AVDD
JP3
OPA_VDD
AGND
JP2
AGND
U5_AVDD
U5_DVDD
U5_SCLK
U5_SDO
U5_CS
U5_AINP
U5_AINM
AGND
U5_AVDD
U5_DVDD
U5_SCLK
U5_SDO
U5_CS
U5_AINP
U5_AINM
5
6
7
B
OPA2836QDGKRQ1
U7B
2
3
1
A
OPA2836QDGKRQ1
U7A
AVDD 7
DVDD 1
CS 4
AINM
5
AINP
6
SCLK 2
SDO 3
GND
8
ADS7044IDCUR
U9
DNP
CS 1
SDO 2
SCLK 3
DVDD 4
GND
5
AVDD 6 AINP
7
AINM
8
ADS7057IRUGR
U5
1
2 3 4 5
J2
1
2 3 4
5
J3
100nF
C13
1µF
C15
1µF
C16
Replace R43 and R44 with 100nF
capacitors when OPA_VSS ≠ AGND
0
R44
100nFC23DNP
100nFC24DNP
Figure 2-3. Differential Input Path on the ADS704X-5XEVM
Signals connected to the differential input path are applied to a differential amplifier in an inverting configuration
whose common-mode voltage is set by VBIAS. The output of the amplifier connects to an RC filter (R25, R27,
and C17) that then connects to the ADC input. Each amplifier feedback loop has an option for a compensation
capacitor via C23 or C24, but these capacitors are not required for good performance. The amplifier power
supplies are connected by default to the OPA_VDD and OPA_VSS supplies. Section 2.2 explains how to modify
the EVM to use external supplies.
Figure 2-3 also shows all connections to the ADC (U5). Each power-supply connection has a 1-μF decoupling
capacitor. The supply connections also have a series 0-Ω resistor that can be removed for the purpose
of making external current measurements. Moreover, each digital input has a 49.9-Ω series resistor. These
resistors smooth the edges of the digital signals to minimize overshoot and ringing.
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Finally, Figure 2-3 identifies a do-not-populate (DNP) component in U9. This ADC footprint is on the bottom of
the board and can be used to evaluate any differential ADC in a VSSOP package in Table 1-2. However, ensure
that any device in U5 is cleanly removed before soldering a device in U9. Section 4.6 explains how to use the
ADS704X-5XEVM GUI to update the EEPROM when the ADC is replaced.
2.2 Power Supplies
The default state of the EVM has all power supplies derived from the USB power and delivered by the PHI
controller. The 3.3-V ADC digital supply voltage (DVDD) is provided by the PHI via pin 50 on J4 (see Figure
2-7). The PHI also provides a regulated 5.5-V power rail that feeds into two LDOs on the EVM. These LDOs
generate a low-noise, 3.6-V (nominal) supply voltage for the amplifier (OPA_VDD) and a low-noise, 3.3-V
(nominal) analog supply voltage for the ADC (AVDD). Figure 2-4 shows the two LDO circuits used on the
ADS704X-5XEVM.
OPA_VDD
100k
R7
100k
R9
AVDD
AGND
EVM_REG_5V5
0
R2
0
R8
0
R1
0
R6
IN
1
EN
3
BYPASS 4
FB 5
OUT 6
2
GND
TPS79101DBVR
U1
IN
1
EN
3
BYPASS 4
FB 5
OUT 6
2
GND
TPS79101DBVR
U2
15pF
C19
15pF
C5
51.1k
R33
30.1k
R34
30.1k
R32
59.0k
R31
10V
10uF
C7
10V
10uF
C20
0
R39
DNP
10nF
C18
10nF
C21
1µF
C4
1µF
C6
100k
R5
301k
R3
AVDD/4
AGND
AVDD/2
Figure 2-4. Power Tree on the ADS704X-5XEVM
In Figure 2-4, the top LDO (U1) has an adjustable output set by resistors R31 and R32 while the bottom
LDO (U2) has an adjustable output set by resistors R33 and R34. Modify these resistor values if a different
OPA_VDD or AVDD voltage is desired. Ensure that the input, absolute, and common-mode voltage limitations
for all components are within data sheet limits when modifying the power supplies. See the LDO data sheet for
more information on how to choose resistor values for a specific output voltage.
If external power supplies are desired, remove resistors R1 and R6 in Figure 2-4 to disconnect both LDOs from
the power-supply circuit. Connector JP4 in Figure 2-5 can then be used to provide direct power to OPA_VDD,
AVDD, and OPA_VSS.
1
2
3
JP4
0
R4
OPA_VDD
AGND
OPA_VSS
AVDD
Figure 2-5. External Power-Supply Header on the ADS704X-5XEVM
If OPA_VSS is connected to any voltage other than AGND, remove R4 in Figure 2-5 and replace R43 and R44
per the instructions in Figure 2-2. Another important consideration if OPA_VSS is modified is that the V– input
(pin 4) on the buffer amplifier in Figure 2-6 is hard-wired to AGND and is therefore unaffected when the voltage
on OPA_VSS is changed.
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1
3
2
48
OPA2320AIDGKR
U10A
7
5
6
4
8
OPA2320AIDGKR
U10B
AGND
100nF
C25
OPA_VDD
OPA_VDD
0
R45
DNP
AGND
AVDD/4
VBIAS
AINM
AVDD/2
Figure 2-6. Buffer Amplifier Circuit on the ADS704X-5XEVM
The buffer amplifier in Figure 2-6 prevents the AVDD/4 resistor divider (R3 and R5) from loading the amplifier
inputs and the AVDD/2 resistor divider (R7 and R9) from loading the ADC inputs (see Figure 2-4). As per Section
2.1.1, VBIAS sets the driver amplifier common-mode voltage for both signal paths. AINM is only required if U3 or
U5 in Figure 2-2 is populated with the ADS7043. This specific ADC has a pseudo-differential input that requires
the AINM pin to be set to AVDD / 2 ±100 mV.
When the ADS7043 is used on the ADS704X-5XEVM:
• Populate R39 in Figure 2-4 with a 0-Ω resistor
• Populate R45 in Figure 2-6 with a 0-Ω resistor
• Depopulate R40 in Figure 2-2
2.3 Digital Interface and Communication
The EVM interfaces with the PHI and communicates with the computer over the USB. There are three devices
on the EVM with which the PHI communicates: the two ADCs (over SPI) and the EEPROM (over I2C). The
EEPROM comes preprogrammed with the information required to configure and initialize each ADC populated
by default on the ADS704X-5XEVM. Therefore, communication with the EEPROM is only required if the user
removes and replaces one of the default ADCs. See Section 2.4 for more information.
All ADCs supported by the ADS704X-5XEVM use SPI serial communication in mode 1 (CPOL = 0, CPHA
= 1). The ADS704X-5XEVM offers 49.9-Ω resistors between the SPI signals to aid with signal integrity (see
Figure 2-2) because the serial clock (SCLK) frequency can be as fast as 60 MHz. Typically, in high-speed SPI
communication, fast signal edges can cause overshoot; these 49.9-Ω resistors slow down the signal edges to
minimize signal overshoot. JP5 provides test points to measure the digital signals, as illustrated in Figure 2-7.
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EVM_ID_SDA
EVM_ID_SCL
EVM_REG_5V5
EVM_ID_PWR
SDO_A
SCLK_AB
AGND
AGND
AGND
11
33
55
77
99
11 11
13 13
15 15
17 17
19 19
21 21
23 23
25 25
27 27
29 29
31 31
33 33
35 35
37 37
39 39
41 41
43 43
45 45
47 47
49 49
51 51
53 53
55 55
57 57
59 59
2
2
4
4
6
6
8
8
10
10
12
12
14
14
16
16
18
18
20
20
22
22
24
24
26
26
28
28
30
30
32
32
34
34
36
36
38
38
40
40
42
42
44
44
46
46
48
48
50
50
52
52
54
54
56
56
58
58
60
60
GND
MP1
GND
MP2 GND MP3
GND MP4
J4
QTH-030-01-L-D-A
EVM_ID_WP
CS_B
SDO_B
CS_A
AGND
1 2
3 4
5 6
7 8
9 10
JP5
TSW-105-07-G-D
0
R13
EVM_DVDD EVM_CAP
Figure 2-7. Digital Communication and PHI Connector on the ADS704X-5XEVM
2.4 I2C Bus for Onboard EEPROM
The circuit shown in Figure 2-8 is used with the PHI board to identify the specific ADCs populated on the
EVM and enable the correct GUI settings. The user does not need to modify or interact with this circuit during
EVM operation. As a result, switch S1 is set by default to enable the EEPROM write protect and must not be
altered unless the ADC is modified as per Section 2.1.1 or Section 2.1.2. Update the EEPROM when the ADC is
replaced using the ADS704X-5XEVM GUI, as per Section 4.6.
EVM_ID_SDA
EVM_ID_SCL
WP
EVM_ID_PWR EVM_ID_PWR
AGND
AGND
AGND
A0
1
A1
2
A2
3
VSS
4SDA 5
SCL 6
WP 7
VCC 8
U4
BR24G32FVT-3AGE2
2
1
3
S1
CAS-120TA
0R10
DNP EVM_ID_WP
10.0k
R26
10.0k
R28
100nF
C22
Figure 2-8. EEPROM Circuit on the ADS704X-5XEVM
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3 ADS704X-5XEVM Software Installation
Download the latest version of the EVM GUI installer from the Tools and Software section on the
ADS704X-5XEVM product folder and run the GUI installer to install the EVM GUI software on your computer.
Note
Manually disable any antivirus software running on the computer before downloading the EVM GUI
installer onto the local hard disk. Depending on the antivirus settings, an error message may appear
or the installer.exe file may be deleted.
As shown in Figure 3-1, accept the license agreements and follow the on-screen instructions to complete the
installation.
Figure 3-1. Software Installation and Prompts
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