Texas Instruments ADS794xEVM User Manual

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User manual (31 pages)

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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

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.

ADCPro is a trademark of Texas Instruments.

Microsoft, Windows are registered trademarks of Microsoft Corporation.

SPI is a trademark of Motorola, Inc.

C is a trademark of NXP Semiconductors.

All other trademarks are the property of their respective owners.

SBAU194 – August 2011

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ADS794xEVM and ADS794xEVM-PDK

ADS794xEVM-PDK

ADS7945

devices (ADS794x). Both devices are 14-bit, dual-channel,

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Summary of Contents for Texas Instruments ADS794xEVM

Page 1 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...
Page 2: Table Of Contents
................ADS794xEVM-PDK: Software Installation ..................ADS794xEVM-PDK Kit Operation ................Bill of Materials, Schematics, and Layout List of Figures ................ADS794xEVM and ADS7945 Analog Inputs ................ADS794xEVM and ADS7946 Analog Inputs ................ADS794xEVM Default Jumper Locations ..................ADS794xEVM-PDK Plug-In Installer ................
Page 3: Evm Overview
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.
Page 4: Analog Interface
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.
Page 5: Ads794Xevm And Ads7945 Analog Inputs
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. ADS7945 OPA836 in Inverting AIN0N (pin 6) Configuration...
Page 6: Ads794Xevm And Ads7946 Analog Inputs
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. ADS7946 No SMA Open AIN0N (pin 6)
Page 7: Digital Interface
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-Ω resistors between the SPI signals and P1 to aid with signal integrity. Typically, in high-speed SPI communication, fast signal edges can cause overshoot;...
Page 8: Power Supplies
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.
Page 9: Evm Operation
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.
Page 10: Ads794Xevm-Pdk: Software Installation
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).
Page 11: Ads794Xevm-Pdk Plug-In Installer
#> 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.
Page 12: Mmb0 Jumper Locations
• 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.
Page 13: Connecting Ads794Xevm To Mmb0
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.
Page 14: Powering Up Ads794Xevm-Pdk
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...
Page 15: Ni-Visa Driver Installation 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.
Page 16: Usbstyx Driver Installation Prompt
Exit button in the small-pop up window. Step 6. Close ADCPro after the USBStyx driver has been installed. SBAU194 – August 2011 ADS794xEVM and ADS794xEVM-PDK Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated...
Page 17: Ads794Xevm-Pdk Kit Operation
The following sections describe how to use ADCPro and the ADS794xEVM plug-in to acquire data. 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.
Page 18: Ads794Xevm Plug-In: Device Configuration Tab
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.
Page 19: Adcpro Test Plug-Ins
ADS794xEVM-PDK Kit Operation www.ti.com 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.
Page 20: Bill Of Materials, Schematics, And Layout
Bill of Materials, Schematics, and Layout www.ti.com 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 Section 8.2 shows the PCB layouts for the ADS794xEVM.
Page 21 Bill of Materials, Schematics, and Layout www.ti.com Table 5. ADS794xEVM Bill of Materials (continued) Item No. ADS7945 ADS7946 Ref Des Description Vendor Part Number R20, R21, R26, Resistor, Thick Film Chip, 1%, Vishay/Dale CRCW06034R99FKEA 1/10W, 0603 R16, R17, R24, Resistor, Metal Film Chip, 0.1%,...
Page 22: Ads794Xevm Pcb: Top Layer
PCB layouts for the ADS794xEVM. NOTE: Board layouts are not to scale. These figures are intended to show how the board is laid out; they are not intended to be used for manufacturing ADS794xEVM PCBs. Figure 14. ADS794xEVM PCB: Top Layer Figure 15.
Page 23: Ads794Xevm Pcb: Power Layer
Bill of Materials, Schematics, and Layout www.ti.com Figure 16. ADS794xEVM PCB: Power Layer Figure 17. ADS794xEVM PCB: Bottom Layer SBAU194 – August 2011 ADS794xEVM and ADS794xEVM-PDK Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated...
Page 24 +5VA UN_POL_VCM +5VA 1000p 4.99 +3.3VD OPA836IDBVT 1000p 1000p 2.2p A1(+) A1(-) Texas Instruments, Inc. PRECISION ANALOG PRODUCTS 0.1u +5VA HIGH-PERFORMANCE ANALOG DIVISION AGND SEMICONDUCTOR GROUP UN_POL_VCM 5411 EAST WILLIAMS BOULEVARD, TUCSON, AZ 85711 USA AGND DESIGNED BY: 1000p TITLE:...
Page 25 Evaluation Board/Kit Important Notice Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation board/kit is intended for use for ENGINEERING DEVELOPMENT, DEMONSTRATION, OR EVALUATION PURPOSES ONLY and is not considered by TI to be a finished end-product fit for general consumer use. Persons handling the product(s) must have electronics training and observe good engineering practice standards.
Page 26: Important Notice
IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete.

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