Texas Instruments ADS7042EVM-PDK User manual

User's Guide
SBAU234A–October 2014–Revised November 2014
ADS7042EVM-PDK
This user's guide describes the characteristics, operation and use of the ADS7042-EVM performance
demonstration kit (PDK). This kit is an evaluation platform for the ADS7042 low power, 12-bit, successive
approximation register (SAR) analog-to-digital converters (ADCs) that supports single-ended analog
inputs.
This EVM eases the evaluation of the ADS7042 device with hardware and software for computer
connectivity through universal serial bus (USB). This user's guide includes complete circuit descriptions,
schematic diagrams, and a bill of materials.
The following related documents are available through the Texas Instruments web site at
http://www.ti.com.
Table 1. Related Documentation
Device Literature Number
OPA835 SLOS713
TPS79101 SLVS325
REG71055 SBAS221
TPS62080 SLVSAE8
TPS3836K33 SGLS322
Contents
1 Overview...................................................................................................................... 3
1.1 ADS7042 EVM Features........................................................................................... 3
1.2 ADS7042EVM-PDK Features..................................................................................... 3
2 EVM Analog Interface....................................................................................................... 3
3 Power Supplies .............................................................................................................. 4
4 Digital Interface .............................................................................................................. 5
5 ADS7042EVM-PDK Initial Setup .......................................................................................... 5
5.1 Default Jumper Settings ........................................................................................... 5
5.2 Software Installation................................................................................................ 5
6 ADS7042EVM-PDK Kit Operation ....................................................................................... 11
6.1 About the SCC Controller Board ................................................................................ 11
6.2 Loading the ADS7042EVM Software........................................................................... 11
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6.3 Capturing Data with the ADS7042-PDK........................................................................ 12
6.4 FFT Analysis....................................................................................................... 14
6.5 Histogram Analysis................................................................................................ 15
6.6 Offset Calibration.................................................................................................. 16
6.7 Estimated Current Consumption ................................................................................ 17
6.8 Troubleshooting ................................................................................................... 17
7 Bill of Materials, PCB Layout, and Schematics......................................................................... 18
7.1 Bill of Materials .................................................................................................... 18
7.2 PCB Layout ........................................................................................................ 20
7.3 Schematics......................................................................................................... 22
List of Figures
1 ADS7042EVM Analog Input Connections................................................................................ 3
2 ADS7042EVM Default Jumper Settings .................................................................................. 5
3 Bottom View of Simple Capture Card with microSD Memory Card Installed........................................ 6
4 Bottom View of ADS7042EVM Board with microSD Memory Card Installed ....................................... 6
5 Connecting ADS7042EVM Board to Simple Capture Card ............................................................ 7
6 LED Indicators on the Simple Capture Card............................................................................. 7
7 Welcome Screen and Destination Directory Screens................................................................... 8
8 License Agreement and Start Installation Screens...................................................................... 8
9 Progress Bar and Installation Complete Screens ....................................................................... 9
10 Windows 7 Driver Installation Warning ................................................................................... 9
11 Simple Capture Card Driver Installation................................................................................. 10
12 Simple Capture Card Driver Completion................................................................................ 10
13 GUI Display Prompt........................................................................................................ 11
14 Open the Data Capture Page on the GUI............................................................................... 12
15 Data Capture Page......................................................................................................... 13
16 FFT Performance Analysis Page......................................................................................... 14
17 Histogram Analysis Page.................................................................................................. 15
18 Offset Calibration Page.................................................................................................... 16
19 Estimated Current Consumption Page .................................................................................. 17
20 ADS7042EVM PCB: Top Layer (L1)..................................................................................... 20
21 ADS7042EVM PCB: GND Layer (L2) ................................................................................... 20
22 ADS7042EVM PCB: Power Layer (L3).................................................................................. 21
23 ADS7042EVM PCB: Bottom Layer (L4)................................................................................. 21
List of Tables
1 Related Documentation..................................................................................................... 1
2 Analog Input Connections .................................................................................................. 4
3 AVDD Voltage Settings ..................................................................................................... 4
4 AVDD Voltage Settings ..................................................................................................... 4
5 Default Jumper Configurations............................................................................................. 5
6 ADS7042EVM Bill of Materials ........................................................................................... 18
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AVDD (used as
Reference)
OPA_AVDD
VIN+
AINP
AINM GND
AVDD
Device
OPA_AVSS
+R
C
+
±
Anti-Aliasing
Filter
Buffer
Signal
Source ADC
www.ti.com Overview
1 Overview
The ADS7042EVM-PDK is a platform for evaluation of the ADS7042 ADC. The evaluation kit combines
the ADS7042EVM board with a Simple Capture Card controller board. This controller card consists of a TI
Sitara embedded microcontroller (AM3352) and a field-programmable gate array (FPGA). It provides an
interface from the EVM to the computer through a universal serial bus (USB) port. The included software
communicates with the Simple Capture Card, and the controller card provides the power and digital
signals used to communicate with the ADS7042EVM board. These demonstration kits include the
ADS7042EVM board, the Simple Capture Card, a microSD memory card, and an A-to-micro-B USB cable.
1.1 ADS7042 EVM Features
• Contains support circuitry as a design example to match ADC performance
• 3.3-V slave serial peripheral interface (SPI)
• Onboard 5-V analog supply
• Onboard OPA835 (56-MHz bandwidth, Rail-to-Rail Out) ADC input drivers
1.2 ADS7042EVM-PDK Features
• USB port for computer interface
• Easy-to-use evaluation software for Microsoft®Windows®XP, Windows 7, and Windows 8 operating
systems
• Built-in analysis tools including scope, FFT, and histogram displays
• Data collection to text files supported
2 EVM Analog Interface
The ADS7042 is an extremely low-power, extremely small size ADC that supports single-channel ended
analog inputs. The ADS7042EVM uses an OPA835 amplifier to drive the inputs of the ADC. The
ADS7042EVM is designed for easy interfacing to multiple analog sources. SMA connector J3 (please refer
to the schematics in Section 7.3) allows the EVM to have input signals connected through a coaxial cable.
In addition, header connector P2 provides a convenient way to connect input signals. All analog inputs are
buffered by the OPA835 amplifier in order to properly drive the ADS7042 ADC inputs.
Figure 1. ADS7042EVM Analog Input Connections
Table 2 lists the analog interface connectors available. Since the AVDD supply functions as the reference
for the ADC, the voltage provided on the J3 or P2 connector can vary from 0 V to AVDD. Connecting an
input signal greater than AVDD would cause the ADC output codes to saturate.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
All other trademarks are the property of their respective owners.
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Table 2. Analog Input Connections
Reference Designator Signal Description
J3 INP Positive single-ended input provided at the SMA
P2 INP Alternate location to provide the positive single-ended input. Normally not populated on
the board.
3 Power Supplies
The ADS7042 supports a wide range of operation on its analog supplies. The AVDD can operate from
1.8V to 3.6V. The DVDD operates from 1.65 V to 3.6 V, independent of the AVDD supply.
The analog portion of the ADS7042EVM-PDK operates from a 5-V supply. The ADS7042EVM-PDK is
configured to use the onboard regulated analog 5-V supply that in turn generates an AVDD analog supply
using the low-noise TPS79101 LDO. This supply is nominally set to 3.3 V at the factory, but this voltage
maybe changed to any value within the valid range, by modifying the value of R46 as per Table 3. In case
any intermediate value needs to be set, the detailed formula to arrive at these values are available in the
TPS79101 (SGLS160) datasheet.
Table 3. AVDD Voltage Settings
AVDD Voltage R46 R45 C34
1.8 V 14.2 kΩ30.1 kΩ33 pF
2.0 V 19.1 kΩ30.1 kΩ27 pF
2.5 V 31.6 kΩ30.1 kΩ22 pF
3.0 V 43.7 kΩ30.1 kΩ15 pF
3.3 V (default) 51.1 kΩ30.1 kΩ15 pF
3.6 V 59.0 kΩ30.1 kΩ15 pF
Alternatively, AVDD may be set by connecting an external power source through P3. Table 4 describes
the modifications required for on-board or external AVDD supply.
Table 4. AVDD Voltage Settings
AVDD Source Position Setting
Onboard regulated AVDD (set to 3.3 V) P3 Closed
P3 Open
External AVDD R47 Disassembled
CAUTION
The external AVDD supply applied to external connector P3 must not exceed
3.6 V as this may damage the device. The external AVDD supply must be in
the range of 1.8 V to 3.6 V for proper operation of the ADS7042EVM.
The digital portion of the ADS7042 ADC operates from a 3.3-V supply from the Simple Capture Card. The
buffer U12 is included to ensure that the SDO can be driven to the controller with minimal distortion.
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4 Digital Interface
The ADS7042 digital output is available in SPI-compatible format, which makes interfacing with
microprocessors, digital signal processors (DSPs) and FPGAs easy. The ADS7042EVM offers 50-Ω
resistors between the SPI signals and edge connector J1 to aid with signal integrity. Typically, in high-
speed SPI communication, fast signal edges can cause overshoot; these resistors slow down the signal
edges in order to minimize signal overshoot.
The ADS7042EVM has clearly marked test points for all the SPI signals to allow observation of the
interface signals using an oscilloscope.
5 ADS7042EVM-PDK Initial Setup
This section presents the steps required to set up the ADS7042EVM-PDK kit before operation.
5.1 Default Jumper Settings
A silkscreen plot detailing the default jumper settings is shown in Figure 2.
Table 5 explains the configuration for these jumpers.
Figure 2. ADS7042EVM Default Jumper Settings
Table 5. Default Jumper Configurations
Reference Default Description
Designator Position
P2 Open Alternate location for the analog input to the ADS7042EVM (unassembled by default)
P3 Closed Closed to connect on-board 3.3-V supply directly to AVDD of the ADS7042
P4 Open Unassembled, by default
5.2 Software Installation
This section presents the steps required to the install the software. Section 6 explains how to operate the
software to acquire data.
NOTE: Ensure the microSD memory card included in the kit is installed in the microSD socket (P6)
on the back of the Simple Capture Card as well as the microSD socket (J2) before
connecting the EVM to the PC. Also ensure that the cards are not swapped or overwritten. If
the contents of these cards are not available during boot up, Windows will not recognize the
ADS7042EVM-PDK as a connected device.
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Complete the following steps to install the software:
Step 1. Ensure that the microSD memory cards on both the Simple Capture Card and ADS7042 are
installed.
Step 2. Verify jumpers are in the factory-default positions and connect the hardware.
Step 3. Locate, copy and install the ADS7042EVM software to the PC.
Step 4. Complete the device driver installation.
Each of these steps is described in the following subsections.
5.2.1 Install the microSD Memory Cards on the Simple Capture Card Controller Board
As mentioned in the previous section, the ADS7042EVM-PDK includes two microSD memory cards. One
is installed on the microSD socket (P6) at the back of the Simple Capture Card as shown in Figure 3. The
second microSD memory card is installed on the mircoSD socket (J2) at the back of the ADS7042EVM as
shown in Figure 4.
Figure 3. Bottom View of Simple Capture Card with microSD Memory Card Installed
Figure 4. Bottom View of ADS7042EVM Board with microSD Memory Card Installed
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The microSD memory card is formatted at the factory with the necessary firmware files for the Simple
Capture Card to boot properly. In addition to this the microSD card on the EVM contain Simple Capture
Card firmware files (app and MLO files) and the ADS7042EVM-PDK software installation files inside the
ADS7042 EVM V#.#.# folder. <V#.#.#> refers to the installation software version number, and increments
with software installer releases.
5.2.2 Verify Jumpers are in the Factory-Default Position and Connect the Hardware
The ADS7042EVM-PDK includes both the ADS7042EVM and the Simple Capture Card; however, the
boards are shipped unconnected.
Follow these steps to verify that ADS7042EVM-PDK kit is configured and connected properly:
Step 1. Verify the ADS7042EVM jumpers are configured as shown in Figure 2.
Step 2. Verify the microSD card is installed on the back of the Simple Capture Card, as shown in
Figure 3.
Step 3. Verify the microSD card is installed on the back of the EVM board, as shown in Figure 4.
Step 4. Connect the ADS7042EVM board to the Simple Capture Card as Figure 5 illustrates.
Figure 5. Connecting ADS7042EVM Board to Simple Capture Card
Step 5. Connect the Simple Capture Card to the PC through the micro USB cable.
Step 6. Verify that the LED D5 Power Good indicator is illuminated. Wait approximately ten seconds
and verify that diode D2 blinks, indicating that USB communication with the host PC is
functioning properly. Figure 6 shows the location of the LED indicators in the Simple Capture
Card.
Figure 6. LED Indicators on the Simple Capture Card
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5.2.3 Install the ADS7042EVM-PDK Software
The ADS7042 EVM V#.#.# software must be installed on the PC. This software supports the ADS7042-
PDK. Administrator privileges are required to install the EVM software. The following steps list the
directions to install the software:
Step 1. Open Windows Explorer and find the microSD memory card in the browser as a storage
device.
Step 2. Navigate to the ...\ADS7042 EVM Vx.x.x\Volume\ folder.
Step 3. Run the installer by double-clicking the file setup.exe. This action installs the EVM GUI
software and the required and device driver components.
Step 4. After the installer begins, a welcome screen displays. Click Next to continue.
Step 5. A prompt appears with the destination directory; select the default directory
under: ...\Program Files(x86)\Texas Instruments\ADS7042evm\.
Figure 7. Welcome Screen and Destination Directory Screens
Step 6. One or more software license agreements appear. Select I Accept the License Agreement
and click Next.
Step 7. The Start Installation screen appears. Click Next.
Figure 8. License Agreement and Start Installation Screens
Step 8. A progress bar appears; this step takes a few minutes.
Step 9. The progress bar is followed by an Installation Complete notice.
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Figure 9. Progress Bar and Installation Complete Screens
5.2.4 Complete the Simple Capture Card Driver Installation
During installation of the Simple Capture Card driver, a prompt may appear with the Windows security
message shown in Figure 10. Select Install this driver software anyway to install the driver required for
proper operation of the software. The drivers contained within the installers are safe for installation to your
system.
Figure 10. Windows 7 Driver Installation Warning
NOTE: Driver installation prompts do not appear if the Simple Capture Card driver has been
installed on your system previously.
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The following steps describe how to install the Simple Capture Card driver:
Step 1. Immediately after the ADS7042 EVM software installation is complete, prompts appear to
install the Simple Capture Card driver, as shown in Figure 11 and Figure 12.
Step 2. A computer restart may be required to finish the software installation. If prompted, restart the
PC to complete the installation.
Figure 11. Simple Capture Card Driver Installation
Figure 12. Simple Capture Card Driver Completion
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