Table of Contents
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This users guide describes the characteristics, operation, and use of the
ADS7881/ADS7891 12-Bit/14-Bit, parallel, analog-to-digital converter evaluation mod-
ule. A complete circuit description, as well as schematic diagram, layout and bill of
materials, are included.
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SLAU150 - December 2004
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ADS7881/ADS7891EVM
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List of Tables
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User's Guide
SLAU150 - December 2004
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ADS7881/ADS7891EVM
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Summary of Contents for Texas Instruments ADS7881
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Page 1: Table Of Contents
SLAU150 – December 2004 ADS7881/ADS7891EVM This users guide describes the characteristics, operation, and use of the ADS7881/ADS7891 12-Bit/14-Bit, parallel, analog-to-digital converter evaluation mod- ule. A complete circuit description, as well as schematic diagram, layout and bill of materials, are included. -
Page 2: Evm Overview
Related Documentation from Texas Instruments Related Documentation from Texas Instruments To obtain a copy of any of the following TI documents, call the Texas Instruments Literature Response Center at (800) 477-8924 or the Product Information Center (PIC) at (972) 644-5580. When ordering, identify this booklet by its title and literature number. -
Page 3: Ads7881 Input Buffer Circuit
All odd numbered pins of P1 are tied to AGND. Signal Conditioning The factory recommends the analog input to any SAR type converter be buffered and low pass filtered. This input buffer on the ADS7881/ADS7891EVM utilizes the THS4031 configured as an INVERTING gain of one, as shown in Figure 1. -
Page 4: Digital Interface
Digital Interface Reference The ADS7881/ADS7891EVM provides an onboard 2.5V reference circuit. The EVM also has the provision for users to supply a reference voltage via connecter P1 pin 20. This reference voltage can be filtered through amplifier U1. The converter itself has on-chip reference buffer, therefore it is not necessary to buffer externally. -
Page 5: Jumper Settings
P3.17 Buffered Data Bit 8 P3.19 Buffered Data Bit 9 P3.21 Buffered Data Bit 10 P3.23 Buffered Data Bit 11 (MSB - ADS7881) P3.25 Buffered Data Bit 12 P3.27 Buffered Data Bit 13 (MSB - ADS7891) P3.29 Not connected P3.31 Not connected All even numbered pins of P3 are tied to DGND. -
Page 6: Power Supplies
Set jumper W5 to short between pins 1-2 or pins 2-3 to short +3.3VD or +5VD, respectively, to be the buffer digital supply (+BVDD). Table 8. Power Connector, J1, Pin Out Signal Power Connector - J1 Signal +VA (+12VA) –VA (–12VA) +AVCC(+5VA) AGND +3.3VD +5VD ADS7881/ADS7891EVM SLAU150 – December 2004... -
Page 7: Using The Evm
(DSK). The ADS7881EVM/ADS7891EVM is then mapped into the processor's memory space. This card also provides an area for signal conditioning. This area can be used to install application circuit(s) for digitization by the ADS7881 and/or ADS7891 analog-to-digital converter. Refer to the 5-6K interface card user's guide (SLAU104) for more information. -
Page 8: Appendix Aads7881Evm/Ads7891Evm Bill Of Materials
www.ti.com Appendix A Appendix A ADS7881EVM/ADS7891EVM Bill of Materials The following table contains a complete Bill of Materials for the ADS7881EVM/ADS7891EVM. The schematic diagram is also provided for reference. Contact the Product Information Center or e-mail dataconvapps@list.ti.com for questions regarding this EVM. Table A-1. - Page 9 NOT INSTALLED NOT INSTALLED REF3040, 50 ppm/–C, 50-A in SOT23-3 CMOS voltage refer- ence ADS7881 SOCKET_48 QFPP Texas Instruments ADS7881IPFBT ADS7881, 12-bit, 4 MSPS ADS7891 ADS7891IPFBT ADS7891, 14-bit, 3 MSPS SN74AHC245 U5 U6 U7 20-TSSOP(PW) Texas Instruments SN74AHC245PWR Octal bus transceiver, 3-state...
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Page 10: Appendix Bads7881Evm/Ads7891Evm Layout
www.ti.com Appendix B Appendix B ADS7881EVM/ADS7891EVM Layout Figure B-1. Top Layer – Layer 1 ADS7881EVM/ADS7891EVM Layout SLAU150 – December 2004... -
Page 11: Ground Plane - Layer 2
www.ti.com Appendix B Figure B-2. Ground Plane – Layer 2 SLAU150 – December 2004 ADS7881EVM/ADS7891EVM Layout... -
Page 12: Power Plane - Layer 3
www.ti.com Appendix B Figure B-3. Power Plane – Layer 3 ADS7881EVM/ADS7891EVM Layout SLAU150 – December 2004... -
Page 13: Bottom Layer - Layer 4
www.ti.com Appendix B Figure B-4. Bottom Layer – Layer 4 SLAU150 – December 2004 ADS7881EVM/ADS7891EVM Layout... -
Page 14: Appendix Cads7881Evm/Ads7891Evm Schematic
www.ti.com Appendix C Appendix C ADS7881EVM/ADS7891EVM Schematic See attachment for schematic drawings. ADS7881EVM/ADS7891EVM Schematic SLAU150 – December 2004... - Page 15 Revision History ECN Number Approved Analog Circuits & A/D 11 12 13 14 15 16 17 18 19 20 EXT_REF Analog Input Power & Digital Buffer TP12 TP14 B_DB[13...0] B_DB[13...0] B_DB0 +AVCC B_DB1 DGND AGND B_DB2 B_DB3 +3.3VD +5VD B_DB4 B_DB5 Power Supply TP11...
- Page 16 Installed on ADS7881EVM 0.01uF 2.2uF R13 : 12 Ohm -VCC C16 : 1000pF C0G 0.1uF U4 : ADS7881 Installed on ADS7891EVM R13 =10 Ohm C16 = 1500 pF C0G U4 : ADS7891 130pF 12500 TI Boulevard. Dallas, Texas 75243 TITLE:...
- Page 17 Revision History ECN Number Approved +5VCC +VCC +AVCC MMZ2012R601A MMZ2012R601A 0.1uF 0.01uF 10uF 10uF 1000pF 10uF 0.01uF 1000pF 10uF TP13 +VBD 10uF +BVDD 0.01uF 1000pF 10uF MMZ2012R601A 10uF 0.1uF 0.01uF 10uF 1000pF MMZ2012R601A -VCC +VBD 0.1uF DB[17...0] B_RD DB[17...0] +VBD +VBD B_DB0 B_DB1...
- Page 18 EVM IMPORTANT NOTICE Texas Instruments (TI) provides the enclosed product(s) under the following conditions: This evaluation kit being sold by TI is intended for use for ENGINEERING DEVELOPMENT OR EVALUATION PURPOSES ONLY and is not considered by TI to be fit for commercial use.
- Page 19 TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products...
- Page 20 Mouser Electronics Authorized Distributor Click to View Pricing, Inventory, Delivery & Lifecycle Information: Texas Instruments ADS7891EVM ADS7881EVM...
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