Texas Instruments ADS794xEVM User manual

User's Guide
SBAU194–August 2011
ADS794xEVM and ADS794xEVM-PDK
ADS794xEVM-PDK
This user's guide describes the characteristics, operation, and use of the ADS794xEVM by itself and as
part of the ADS794xEVM-PDK kit. These evaluation modules (EVMs) allow evaluation of all aspects of
either the ADS7946 or ADS7945 devices (ADS794x). Both devices are 14-bit, dual-channel,
ultralow-power, differential successive-approximation-register (SAR) analog-to-digital converters (ADCs)
with a maximum throughput rate of 2 MSPS. The ADS7945 offers fully-differential input voltages while the
pseudo-differential inputs of the ADS7946 offer single-ended input voltages with small common-mode
noise-cancelling capabilities. Complete circuit descriptions, schematic diagrams, and bill of materials are
included in this document.
The following related documents are available through the Texas Instruments web site at
http://www.ti.com.
Related Documentation
Device Literature Number
ADS7945 SBAS539
ADS7946
OPA350 SBOS099C
OPA836 SLOS712B
REF5040 SBOS410E
SN74LVC2G74 SCES203M
ADCPro is a trademark of Texas Instruments.
Microsoft, Windows are registered trademarks of Microsoft Corporation.
SPI is a trademark of Motorola, Inc.
I2C is a trademark of NXP Semiconductors.
All other trademarks are the property of their respective owners.
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Contents
1 EVM Overview ............................................................................................................... 3
2 Analog Interface ............................................................................................................. 4
3 Digital Interface .............................................................................................................. 7
4 Power Supplies .............................................................................................................. 8
5 EVM Operation .............................................................................................................. 9
6 ADS794xEVM-PDK: Software Installation ............................................................................. 10
7 ADS794xEVM-PDK Kit Operation ....................................................................................... 17
8 Bill of Materials, Schematics, and Layout .............................................................................. 20
List of Figures
1 ADS794xEVM and ADS7945 Analog Inputs ............................................................................ 5
2 ADS794xEVM and ADS7946 Analog Inputs ............................................................................ 6
3 ADS794xEVM Default Jumper Locations .............................................................................. 10
4 ADS794xEVM-PDK Plug-In Installer.................................................................................... 11
5 Completed ADS794xEVM-PDK Installer ............................................................................... 11
6 MMB0 Jumper Locations................................................................................................. 12
7 Connecting ADS794xEVM to MMB0.................................................................................... 13
8 Powering Up ADS794xEVM-PDK....................................................................................... 14
9 NI-VISA Driver Installation Prompt...................................................................................... 15
10 Loading ADS794xEVM Plug-in From ADCPro ........................................................................ 15
11 USBStyx Driver Installation Prompt..................................................................................... 16
12 ADS794xEVM Plug-in: Device Configuration Tab .................................................................... 18
13 ADCPro Test Plug-ins .................................................................................................... 19
14 ADS794xEVM PCB: Top Layer.......................................................................................... 22
15 ADS794xEVM PCB: Ground Layer ..................................................................................... 22
16 ADS794xEVM PCB: Power Layer....................................................................................... 23
17 ADS794xEVM PCB: Bottom Layer...................................................................................... 23
List of Tables
1 P2: Analog Interface Pinout (Samtec 10 x 2) ........................................................................... 4
2 SMA Analog Inputs ......................................................................................................... 4
3 P1: Serial Interface Header................................................................................................ 7
4 P3 Configuration: Power-Supply Interface Header..................................................................... 8
5 ADS794xEVM Bill of Materials .......................................................................................... 20
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1 EVM Overview
1.1 Features
ADS794xEVM Features:
•Contains all support circuitry needed for the ADS7946/ADS7945 (ADS794x)
•5-V, 3.3-V, and 1.8-V logic compatible with 16-bit, 40-MHz SPI™serial interface
•Simple channel selection with a single 16-bit word command
•Serial interface header for easy connection to TI DSP-based communication systems
•Compatible with the TI Modular EVM System
•Voltage reference options: onboard REF5040 (4.096-V) reference or external reference
•Voltage reference buffering with OPA350
•Onboard OPA836 (200-MHz BW, 1-mA quiescent current) ADC input drivers
•Jumper-selectable bipolar (–VREF/2 to +VREF/2) or unipolar (0 V to VREF) input range
ADS794xEVM-PDK Features:
•Easy-to-use evaluation software for Microsoft®Windows®XP operating system PCs
•Data collection to text files
•Built-in analysis tools including scope, FFT, and histogram displays
•Complete control of board settings
•Easily expandable with new analysis plug-in tools from Texas Instruments
The ADS794xEVM-PDK is available for use with a computer. This kit combines the ADS794xEVM board
with the DSP-based MMB0 motherboard, and includes ADCPro™software for evaluation.
The MMB0 motherboard allows the ADS794xEVM to be connected to the computer via an available USB
port. This manual shows how to use the MMB0 as part of the ADS794xEVM-PDK, but does not provide
technical details about the MMB0 itself.
ADCPro is a program for collecting, recording, and analyzing data from ADC evaluation boards. It is based
on a number of plug-in programs, so it can be expanded easily with new test and data collection plug-ins.
The ADS794xEVM-PDK is controlled by a plug-in running in ADCPro. For more information about
ADCPro, see the ADCPro™Analog-to-Digital Converter Evaluation Software User's Guide (literature
number SBAU128), available for download from the TI web site.
This manual covers the operation of both the ADS794xEVM and the ADS794xEVM-PDK. Throughout this
document, the abbreviation EVM and the term evaluation module are synonymous with the ADS794xEVM.
Operation of the EVM and kit for both the ADS7946 and the ADS7945 devices is identical, unless
otherwise noted.
1.2 Introduction
The ADS794xEVM is an evaluation module built to the TI Modular EVM System specifications. It can be
connected to any modular EVM system interface card.
The ADS794xEVM is available as a stand-alone printed circuit board (PCB) or as part of the
ADS794xEVM-PDK, which includes an MMB0 motherboard and software. As a stand-alone PCB, the
ADS794xEVM is useful for prototyping designs and firmware because it offers circuitry that meets the
product data sheet specifications of either the ADS7946 or ADS7945 devices.
The ADS7945 and ADS7946 are 14-bit, 2-MSPS ADCs with fully differential and pseudo-differential
unipolar inputs, respectively. These devices operate at a 2-MSPS sample rate with a 16-clock SPI data
frame that features both outstanding dc and excellent dynamic performance. These devices also include a
two-channel input multiplexer and a low-power SAR ADC with an inherent sample-and-hold (S/H) input
stage. During normal operation at 2 MSPS, the ADS794x dissipates a mere 11.6 mW.
Note that the ADS794xEVM has no microprocessor and cannot run software. Therefore, some type of
interface is required to connect the ADS794xEVM to a computer. In the ADS794xEVM-PDK kit, the MMB0
motherboard serves as the interface between the computer and the ADS794xEVM board.
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2 Analog Interface
The ADS794xEVM is designed for easy interfacing to multiple analog sources. SMA connectors allow the
EVM to have input signals connected via coaxial cables. In addition, the Samtec connector provides a
convenient 10-pin, dual-row, header/socket combination at P2. This header/socket provides access to the
analog input pins of the ADS794x. Consult Samtec at http://www.samtec.com or call 1-800-SAMTEC-9 for
a variety of mating connector options. All analog inputs are buffered by OPA836 high-speed operational
amplifiers in order to properly drive the ADS794x ADC inputs.
Use appropriate caution when handling these pins. Table 1 summarizes the pinout for analog interface P2.
Table 1. P2: Analog Interface Pinout (Samtec 10 x 2)
Pin Number Signal Description
CH0 positive differential input for ADS7945; open if
P2.2 A0(+) / OPEN ADS7946 is installed
CH0 negative differential input for ADS7945;
P2.4 A0(–)single-ended input for ADS7946
CH1 positive differential input for ADS7945; open if
P2.10 A1(+) / OPEN ADS7946 is installed
CH1 negative differential input for ADS7945;
P2.12 A1(–)single-ended input for ADS7946
P2.1-19 (odd) GND Analog ground connections (except J1.15)
P2.6 and P2.8 GND Analog ground connections
P2.14, P2.16, and P2.18 GND Analog ground connections
Unbuffered output. VREF/4 (J6 open) or VREF/2 (J6
P2.15 VREF/4 or VREF/2 closed)
P2.20 Ext VREF External reference voltage input
Table 2 lists the SMA analog inputs.
Table 2. SMA Analog Inputs
Pin Number Signal Description
CH0 positive differential input for ADS7945; no
J10 A0(+) / No SMA SMA if ADS7946 is installed
CH0 negative differential input for ADS7945;
J11 A0(–)single-ended input for ADS7946
CH1 positive differential input for ADS7945; no
J4 A1(+) / No SMA SMA if ADS7946 is installed
CH1 negative differential input for ADS7945;
J5 A1(–)single-ended input for ADS7946
As noted in Table 1 and Table 2, there are different hardware configurations depending on the installed
converter. The ADS7945 uses two inputs per channel because of its fully differential inputs. The ADS7946
uses one input per channel for its pseudo-differential inputs.
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4
10
12
SMA
J10
SMA
J11
SMA
J4
SMA
J5
A0(+)
A1(+)
A0( )-
A1( )-
OPA836 in Inverting
Configuration
OPA836 in Inverting
Configuration
OPA836 in Inverting
Configuration
OPA836 in Inverting
Configuration
P2
AIN1P (pin 8)
AIN1N (pin 7)
AIN0P (pin 5)
AIN0N (pin 6)
ADS7945
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2.1 ADS794xEVM Analog Inputs with ADS7945 Installed
Each channel of the ADS7945 uses two OPA836 operational amplifiers to drive the fully differential inputs.
The input signals can be applied to either the SMA or P2 header connectors. These operational amplifiers
offset the input signal to use an inverting configuration with a single supply. The EVM Operation section
explains in detail how this offset is used to allow bipolar signals for the ADS7945 with jumper J6.
Figure 1 illustrates the ADS794xEVM analog inputs with the ADS7945 installed.
Figure 1. ADS794xEVM and ADS7945 Analog Inputs
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4
10
12
No SMA
J10
SMA
J11
No SMA
J4
SMA
J5
A0(+)
A1(+)
A0( )-
A1( )-
OPA836 in Inverting
Configuration
OPA836 in Inverting
Configuration
P2
AIN1P (pin 8)
AIN1N (pin 7)
AIN0P (pin 5)
AIN0N (pin 6)
ADS7946
Open
Open
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2.2 ADS794xEVM Analog Inputs with ADS7946 Installed
Each channel of the ADS7946 uses one OPA836 to drive a single-ended input voltage. The input signals
can be applied to either the SMA or P2 header connectors. These operational amplifiers offset the input
signal to use an inverting configuration with a single supply. The EVM Operation section explains in detail
how this offset is used to allow bipolar signals for the ADS7946 with jumper J6.
Figure 2 shows the ADS794xEVM analog inputs with the ADS7946 installed.
Figure 2. ADS794xEVM and ADS7946 Analog Inputs
2.3 External Reference Input
Pin P2.20 is an analog input for an external reference voltage when J2 is in position 2-3. The source that
provides this external reference should have a voltage between 2.5 V and the analog power-supply
voltage.
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3 Digital Interface
Samtec part numbers SSW-110-22-F-D-VS-K and TSM-110-01-L-DV-P provide a convenient 10-pin,
dual-row, header/socket combination at P1. This header/socket provides access to the digital control pins
of the ADC. Consult Samtec at http://www.samtec.com or call 1-800-SAMTEC-9 for a variety of mating
connector options.
Table 3 summarizes the pinouts for digital interface P1.
Table 3. P1: Serial Interface Header
Pin Number Signal Description
P1.1 CS Chip select input. Pulled high with 10-kΩresistor.
P1.3 SCLK Serial clock input
Chip select input. This pin is intended to be used by
P1.7 CS the MMB0 motherboard
P1.11 SDI or MOSI SDI or MOSI input
P1.13 SDO or MISO SDO or MISO output
Power-down input (active high). Pulled down with
P1.19 PDEN 10-kΩresistor.
P1.4, P1.10, and P1.18 GND Digital ground connections
I2C bus; used only used to program the U4
P1.16, P1.20 I2C™bus EEPROM on the EVM board
P1.2, P1.5-6, P1.8-9,
P1.12, P1.14-15, and Unused Unused
P1.17
3.1 Serial Interface (SPI)
The ADS794x ADC uses SPI serial communication in mode 0 (CPOL = 0, CPHA = 0). Because the serial
clock (SCLK) frequency can be as fast as 40 MHz, the ADS794xEVM offers 47-Ωresistors between the
SPI signals and P1 to aid with signal integrity. Typically, in high-speed SPI communication, fast signal
edges can cause overshoot; these 47-Ωresistors slow down the signal edges in order to minimize signal
overshoot.
3.2 ADS794x Channel Select as SDI (MISO)
The ADS794x ADC offers direct control over the internal multiplexer using pin 11. The ADS794xEVM uses
a flip-flop (see U9 in the attached schematic) to convert this pin into a typical SPI SDI (MOSI) pin. This
architecture takes advantage of the SPI full-duplex data transmission sequence to control channel
selection at the same time conversion data are acquired. The digital word 0x000 can be used to select
channel 0, and the word 0xFFFF can be used to select channel 1.
3.3 I2C Bus for Onboard EEPROM
The ADS794xEVM has an I2C bus to communicate with the onboard EEPROM that records the board
name and assembly date. It is not used in any form by the ADS794x converter.
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4 Power Supplies
P3 is the power-supply input connector. Table 4 lists the configuration details for P3.
Table 4. P3 Configuration: Power-Supply Interface Header
Pin Number Pin Name Function Required
P3.3 +5VA 5-V analog supply Yes
P3.5 GND Digital ground input Yes
P3.6 GND Analog ground input Yes
P3.7 +1.8VD 1.8-V digital supply Yes/Optional
P3.9 +3.3VD 3.3-V digital supply Yes/Optional
P3.10 +5VD 5-V digital supply Yes/Optional
P3.1-2, P3.4, and Unused Unused No
P3.7-8
4.1 Analog Power Options
The ADS794xEVM board is designed to work with a 5-V analog power supply connected to P3.3.
4.2 Digital Power Options
The ADS794xEVM uses a jumper in J3 to connect the digital power supply to either +3.3 VD (P3.10) or +5
VD (P3.9). J3 in position 1-2 connects the digital power supply to +5 VD; position 2-3 connects the digital
power supply to +3.3 VD. Without a jumper in J3, the digital power supply can be connected to +1.8
VD(P3.7) with a jumper wire to pin J3.2. The jumper in J3 must always be in position 2-3 (+3.3 VD) while
using the MMB0 with the EVM.
4.3 Reference Voltages
The ADS794xEVM uses a jumper in J2 to select between the internal (REF5040) and external voltage
reference sources. J2 in position 1-2 selects the internal reference; position 2-3 selects the external
reference. The selected reference is cleaned with a RC filter and buffered with a OPA350 operational
amplifier.
CAUTION
Digital supply and reference voltage must be at or below the analog supply
voltage at all times.
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5 EVM Operation
This section provides information on the analog input, digital control, and general operating conditions of
the ADS794xEVM without the MMB0 motherboard. Software operation is presented in Section 7.
5.1 Analog Input
The ADS794xEVM offers three different analog input modes, selectable with jumper J6 and the type of
input signal. Note that the ADS794x converter by itself only allows dc-coupled unipolar signals. The two
additional input modes are available because OPA836 operational amplifiers drive the analog inputs. It is
preferable for external signal drivers or filters to have low output impedance to reduce gain errors.
Mode 1: DC-Coupled Unipolar Inputs (J6 Closed)
DC-coupled unipolar signals are typically produced by single-supply signal drivers. To allow dc-coupled
unipolar signals, J6 should be closed. This mode allows an input signal range from 0 V to VREF for all EVM
analog inputs. In this mode, the voltage read at the ADC is equal to (VREF –VIN).
Mode 2: DC-Coupled Bipolar Inputs (J6 Open)
DC-coupled bipolar signals are typically produced by dual-supply signal drivers. To allow dc-coupled
bipolar signals, J6 should be open. This mode allows an input signal range from –VREF/2 to +VREF/2 for all
EVM analog inputs. In this mode, the voltage read at the ADC is equal to (VREF/2 –VIN).
Mode 3: AC-Coupled Inputs (J6 Closed)
AC-coupled signals are typically produced by high-pass filters. To allow ac-coupled bipolar signals, J6
should be closed. This mode allows an input signal range from –VREF/2 to +VREF/2 for all EVM analog
inputs. In this mode, the voltage read at the ADC is equal to (VREF/2 –VIN).
5.2 Digital Control
The digital control signals can be applied directly to the P1 header (top or bottom side). The modular
ADS794xEVM can also be connected directly to a DSP or microcontroller interface board, such as the
5-6K Interface or HPA-MCU Interface boards available from Texas Instruments, or the MMB0 if purchased
as part of the ADS794xEVM-PDK. For a list of compatible interface and/or accessory boards for the EVM
or the ADS794x, see the relevant product folder on the TI web site.
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5.3 Default Jumper Settings
Figure 3 shows the jumper locations on the EVM board and the respective factory default conditions for
each.
Figure 3. ADS794xEVM Default Jumper Locations
There are four jumpers on the ADS794xEVM board. These jumpers are used to set the CS signal entry
pin (J1), select the digital logic level (J3), select the reference (J2), and to establish the input signal range
type (J6). The default parameters are:
•The CS signal entry pin is P1.7 (J1: 2-3).
•The logic level is 3.3 V (J3: 2-3).
•The onboard 4.096 V is selected as the reference voltage (J1: 1-2).
•Analog input range is 0 V to VREF (4.096 V) with dc-coupled signals (J6: closed)
6 ADS794xEVM-PDK: Software Installation
This section presents the steps required to the install the software. Section 7 explains how to operate the
software to acquire data.
Complete the following steps to install the software:
Step 1. Install the ADCPro software (if not already installed) on a PC.
Step 2. Install the ADS794xEVM-PDK EVM plug-in software.
Step 3. Set up the ADS794xEVM-PDK hardware.
Step 4. Power up the ADS794xEVM-PDK.
Step 5. Connect the ADS794xEVM-PDK to the computer with a USB cable.
Step 6. Complete the USB driver installation process.
Each task is described in the subsequent sections of this document.
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6.1 Installing the ADCPro Software
CAUTION
Do not connect the ADS794xEVM-PDK to a PC before completing Section 6.2
through Section 6.4. Failure to observe this caution may cause Microsoft
Windows to not recognize the ADS794xEVM-PDK as a connected device.
ADCPro is the primary program used to evaluate ADCs. The latest software version of ADCPro is
available from the TI website at www.ti.com. Refer to the ADCPro User Guide for instructions on installing
and using ADCPro.
6.2 Installing ADS794xEVM-PDK Plug-In Software
The ADS794xEVM-PDK plug-in uses ADCPro; you must install ADCPro before uploading the plug-in.
To install the ADS794xEVM-PDK plug-in, run the file: ads794X-adcproplugin-<version #>.exe (<version
#>refers to the installation file version number, and increments with software version releases).
Double-click the file to run it; then follow the instructions as shown. You can also use the ADCPro Update
Check feature to check for newer versions of the ADS794xEVM-PDK plug-in, once you have installed a
version of it.
Figure 4 and Figure 5 show the initial and completed installer screenshots, respectively.
Figure 4. ADS794xEVM-PDK Plug-In Installer
Figure 5. Completed ADS794xEVM-PDK Installer
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6.3 Configuring the ADS794xEVM-PDK Hardware
The ADS794xEVM-PDK contains both the ADS794xEVM and the MMB0 motherboard; however, the
devices may be shipped unconnected or configured incorrectly. Follow these steps to verify that
ADS794xEVM-PDK kit is properly configured and connected.
Step 1. Unpack the ADS794xEVM-PDK kit.
Step 2. Set the three jumpers on the MMB0 REV D as shown in Figure 6. Below Figure 6, there is a
check list that explains the functionality of each jumper.
Figure 6. MMB0 Jumper Locations
Follow this check list to ensure proper operation of the MMB0 with the ADS794xEVM:
•J12 must be closed. This setting allows the wall supply to power up the MMB0 and the
ADS794xEVM through J2 (6-VDC input), and regulate down to +5 V, 3.3 V, and 1.8 V.
•J13B must be closed. This configuration connects the 5-V analog power supply with the 5-V digital
power supply.
•J13A must be opened. This setting allows the 5-V analog power supply to be regulated onboard.
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Step 3. Plug the ADS794xEVM into the MMB0, as Figure 7 illustrates.
Figure 7. Connecting ADS794xEVM to MMB0
CAUTION
Do not misalign the pins when plugging the ADS794xEVM into the MMB0.
Check the pin alignment carefully before applying power to the PDK.
Step 4. Set jumper J3 on the ADS794xEVM to position 2-3 in order to set the ADS794xEVM logic
voltage to 3.3 V. The MMB0 uses 3.3-V logic to communicate with the ADS7945xEVM.
Step 5. Set jumper J1 on the ADS794xEVM to position 2-3 in order to place the CS signal in P1.7 of
the EVM. The MMB0 sends the CS signal via P1.7.
Step 6. Set jumper J2 on the ADS794xEVM to position 1-2 if the 4.096-V internal (onboard) reference
is used. If an external reference is used, set J2 to the 2-3 position.
CAUTION
If an external reference is used, please do not apply external reference voltage
before the power is applied to the MMB0 motherboard.
Step 7. Set jumper J6 to match the correct type of input signal, as explained in Section 5.1:
•For dc-coupled unipolar input signals, J6 must be closed.
•For dc-oupled bipolar input signals, J6 must be opened.
•For ac-coupled signals, J6 must be closed.
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6.4 Powering Up the ADS794xEVM-PDK
Once the ADS794xEVM-PDK kit is configured, power can be applied to the MMB0. This power comes
from a wall supply that delivers +6 VDC to the MMB0 via J2 on the MMB0 motherboard. This wall power
supply is included with the PDK; it should be connected where Figure 8 indicates.
Figure 8. Powering Up ADS794xEVM-PDK
After the power supply is connected, four green LEDs in the bottom right-hand corner of the MMB0
motherboard should light up. If these LEDs do not light up, disconnect the power and verify that J12 is
closed.
6.5 First-Time Connection: ADS794xEVM-PDK to PC, Completing Driver Installation
The first time that the ADS794xEVM-PDK kit is connected to the PC via USB, the PC prompts the user for
two drivers. At this point, it is presumed that the ADCPro software and the ADS794xEVM plug-in have
been installed, and that the ADS794xEVM-PDK kit is properly configured and powered up (refer to
Section 6.1 through Section 6.4). The following sections show how to install these drivers.
NOTE: Driver prompts may not appear if another PDK kit has been used on the PC before.
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6.5.1 NI-VISA USB Device Driver Installation
Follow these procedures to install the NI-VISA USB device driver, if prompted.
Step 1. With power applied to the PDK kit, connect the PDK kit to the PC via USB.
Step 2. The computer should recognize the new hardware and prompt the user for drivers, as shown
in Figure 9. This driver should be present in the PC hard drive with the ADCPro files. Direct
the PC to search the driver and install it by clicking Next -->at every prompt.
Figure 9. NI-VISA Driver Installation Prompt
6.5.2 USBStyx Driver Installation
The USBStyx driver prompt only appears when the ADCPro software uses the ADS794xEVM plug-in to
communicate with the PDK hardware for the first time. Follow these procedures to install the USBStyx
driver.
Step 1. Make sure that the PDK kit is configured and powered up as explained in Section 6.3 and
Section 6.4. Then, press the Reset button on the MMB0 upper right-hand corner once.
Step 2. Start ADCPro from the Windows Start menu.
Step 3. Load the ADS794xEVM plug-in from the ADCPro EVM drop-down menu as Figure 10
illustrates.
Figure 10. Loading ADS794xEVM Plug-in From ADCPro
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Step 4. Wait for the driver prompt window to appear. When the plug-in is first loaded, the plug-in
searches for the board. You will see a series of messages in the status area indicating this
action; eventually, the driver prompt window will appear, as Figure 11 shows.
Figure 11. USBStyx Driver Installation Prompt
NOTE: If the USBStyx driver was previously installed on the PC, the status area should show the
message Select Device without prompting for the driver. If this message appears, close
ADCpro and proceed to Section 7.
Step 5. This driver should be present in the PC hard drive with the ADCPro files. Direct the PC to
search the driver and install it by clicking Next -->at every prompt. Be patient; it may take
some time for the PC to find the driver.
NOTE: During the driver installation, a small pop-up window may appear indicating that the firmware
load has timed out. Ignore this pop-up. Continue with the USBStyx driver installation. Once
driver installation has finished, click the Exit button in the small-pop up window.
Step 6. Close ADCPro after the USBStyx driver has been installed.
16 ADS794xEVM and ADS794xEVM-PDK SBAU194–August 2011
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www.ti.com ADS794xEVM-PDK Kit Operation
7 ADS794xEVM-PDK Kit Operation
The evaluation software is based on ADCPro. This program operates using a variety of plug-ins. To use
ADCPro, load an EVM plug-in and a test plug-in. To load an EVM plug-in, select it from the EVM menu.
To load a test plug-in, select it from the Test menu. To unload a plug-in, select the Unload option from the
corresponding menu.
The following sections describe how to use ADCPro and the ADS794xEVM plug-in to acquire data.
7.1 About the MMB0
The MMB0 provides the USB interface between the PC and the ADS794xEVM. The MMB0 is a modular
EVM system motherboard. It is designed around the TMS320VC5507, a DSP with an onboard USB
interface from Texas Instruments. The MMB0 also has 16 MB of SDRAM installed.
The MMB0 is not sold as a DSP development board, and it is not available separately. TI cannot offer
support for the MMB0 except as part of an EVM kit. For schematics or other information about the MMB0,
contact Texas Instruments.
7.2 Loading the ADS794xEVM-PDK Plug-in
The ADS794xEVM-PDK plug-in for ADCPro provides complete control over all settings of the ADS794x.
You can adjust the ADS794xEVM settings when you are not acquiring data. During acquisition, all controls
are disabled and settings may not be changed.
When you change a setting on the ADS794xEVM plug-in, the setting immediately updates on the board.
Settings on the ADS794xEVM correspond to settings described in the ADS794x product data sheet
(available for download at http://www.ti.com); see the product data sheet for details.
To load the ADS794xEVM plug-in, follow these steps.
Step 1. Make sure the PDK kit is configured and powered up as explained in Section 6.3 and
Section 6.4. Then, press the Reset button on the MMB0 (in the top right-hand corner) once to
clear the board memory.
Step 2. Start ADCPro from the Windows Start menu.
Step 3. Load the ADS794xEVM plug-in from the ADCPro drop-down EVM menu; see Figure 10. Note
that only one EVM plug-in can be loaded at a time. If a different plug-in is selected, the
previous plug-in is unloaded.
Step 4. When the plug-in is loaded, the plug-in searches for the board. A series of messages in the
status area will indicate this action, eventually showing Select Device...
The plug-in is now loaded and ready to work with the ADS794xEVM.
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7.3 Using the ADS794xEVM Plug-in
The ADS794xEVM plug-in allows the user to evaluate the ADS794x ADC. Figure 12 shows the device
configuration tab of the ADS794xEVM Plug-in. Use this tab of the ADCPro software to configure the
ADS794x.
Figure 12. ADS794xEVM Plug-in: Device Configuration Tab
The device configuration tab contains the following controls.
(1) Device Selection: This control is a user input that must be set by the user, to identify whether the
ADS7945 or ADS7946 is installed on the board.
(2) Channel Select: This user input selects the channel to be sampled.
(3) Data Rate: This control shows the data rate or sampling frequency used by the ADC to acquire data.
(4) Power Down: This option controls the power-down mode of the ADC.
(5) Device Interface Information: This option shows the SPI parameters that are in use while sampling
data. These parameters should appear after a device is selected.
(6) About: This control shows the plug-in version, MMB0 firmware version, ADS794xEVM assembly date,
and ADS794xEVM board revision information. This information should appear after a device is selected.
(7) Collection Bar: This feature shows the percentage of data collected during an acquisition session.
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7.4 Loading the Test Plug-in
Once the ADS794xEVM plug-in is configured in ADCPro, one of the four test plug-ins must be loaded in
ADCPro using the drop-down Test menu, as shown in Figure 13. Note that only one Test plug-in can be
loaded at a time. If a different plug-in is selected, the previous plug-in is unloaded.
Figure 13. ADCPro Test Plug-ins
There are four different test options available for the ADS794xEVM:
•Data monitor: This test acquires data and exports it in table format as hexadecimal data.
•MultiFFT: This test allows the user to acquire data and create an FFT graph of power vs. frequency to
display data
•MultiHistogram: This option acquires data and creates a histogram of code values.
•MultiScope: This feature acquires data and displays it in a graph of voltage vs. time.
For further details regarding how to set up and use the various test plug-ins, refer to the ADCPro User
Guide.
7.5 Acquiring Data
Once the ADS794xEVM is configured for the desired test scenario, press the Acquire button to start the
data collection process; the software collects the number of data points specified in the Test plug-in Block
Size control. While acquiring data, the ADS794xEVM plug-in disables all front panel controls, and the
collection process bar displays the completion progress.
7.6 Troubleshooting
If the ADS794xEVM plug-in cannot find the ADS794xEVM-PDK, press the RESET button on the MMB0
and try again.
If ADCPro stops responding while the ADS794xEVM-PDK is connected, shut down and restart the
ADCPro software. Also, try unplugging the USB cable from the PDK. Unload and reload the plug-in before
reapplying power to the PDK.
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Bill of Materials, Schematics, and Layout www.ti.com
8 Bill of Materials, Schematics, and Layout
Schematics for the ADS794xEVM are appended to this user's guide. The bill of materials is provided in
Table 5.Section 8.2 shows the PCB layouts for the ADS794xEVM.
8.1 Bill of Materials
NOTE: All components should be compliant with the European Union Restriction on Use of
Hazardous Substances (RoHS) Directive. Some part numbers may be either leaded or
RoHS. Verify that purchased components are RoHS-compliant. (For more information about
TI's position on RoHS compliance, see the http://www.ti.com.)
Table 5. ADS794xEVM Bill of Materials
Qty
Item No. ADS7945 ADS7946 Ref Des Description Vendor Part Number
Texas
1 1 1 N/A Printed Circuit Board 6527650
Instruments
C1, C13, C17,
4 4 Capacitor, X7R Ceramic ±10%,
C24
2 Murata GRM188R71C104KA01D
16WV, 0603
2 0 C20, C23
C2, C4, C10, Capacitor, X7R Ceramic ±10%,
3 4 4 TDK C1608X7R1A105K
C14 10WV, 0603
Capacitor, X7R Ceramic ±20%,
4 2 2 C3, C11 Taiyo Yuden JMK316B7226ML-T
6.3WV, 1206
Capacitor, X7R Ceramic ±10%,
5 3 3 C5, C6, C29 Taiyo Yuden JMK212B7106KG-T
6.3WV, 0805
Capacitor, X7R Ceramic ±10%,
6 1 1 C8 Murata GRM188R71A225KE15D
10WV, 0603
C9, C12, C16,
6 6 Capacitor, C0G Ceramic ±5%,
C26, C27, C28
7 Murata GRM1885C1H102JA01D
50WV, 0603
2 0 C22, C25
2 2 C15, C19 Capacitor, C0G Ceramic ±0.1p,
8 TDK C1608C0G1H2R2B
50WV, 0603
2 0 C18, C21
Header, 20-Pin SMT Plug, .100"
9 2 2 P1A, P2A Samtec TSM-110-01-L-DV-P
Gold (2x10)
Header, 20-pin SMT Socket, .100"
10 2 2 P1B, P2B Samtec SSW-110-22-F-D-VS-K
Gold (2x10)
Header, 10-Pin SMT Plug, .100"
11 1 1 P3A Samtec TSM-105-01-L-DV-P
Gold (2x5)
Header, 10-pin SMT Socket, .100"
12 1 1 P3B Samtec SSW-105-22-F-D-VS-K
Gold (2x5)
Header, Strip, 3-pin .100"Gold
13 3 3 J1, J2, J3 Samtec TSW-103-07-L-S
(1x3)
2 2 J5, J11 Amphenol 132134
14 Connector, SMA Jack Straight PCB
2 0 J4, J10 Emerson 142-0701-201
15 1 1 J6 Header Strip, 2-pin .100"Gold (1x2) Samtec TSW-102-07-L-S
R1, R2, R3, R4,
8 8 R8, R28, R31, Resistor, Thick Film Chip, 1%,
16 Panasonic ERJ-3EKF47R0V
R42 1/10W, 0603
2 0 R34, R37
Resistor, Metal Film Chip, 0.1%,
17 1 1 R14 Panasonic ERA-6AEB302V
1/8W, 0805
Resistor, Metal Film Chip, 0.1%,
18 1 1 R30 Panasonic ERA-6AEB152V
1/8W, 0805
Resistor, Metal Film Chip, 0.1%,
19 1 1 R15 Panasonic ERA-6AEB102V
1/8W, 0805
Resistor, Metal Film Chip, 0.1%,
20 1 1 R11 Panasonic ERA-3AEB102V
1/10W, 0603
Resistor, Thick Film Chip, 1%,
21 2 2 R5, R6 Panasonic ERJ-3EKF1002V
1/10W, 0603
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