AMC7820 Evaluation Module User's Guide 2001 Data Acquisition Products SBAU074 IMPORTANT NOTICE Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability. TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI's standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. 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Also see: Standard Terms and Conditions of Sale for Semiconductor Products. www.ti.com/sc/docs/stdterms.htm Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright * 2001, Texas Instruments Incorporated 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. As such, the goods being provided may not be complete in terms of required design-, marketing-, and/or manufacturing-related protective considerations, including product safety measures typically found in the end product incorporating the goods. As a prototype, this product does not fall within the scope of the European Union directive on electromagnetic compatibility and therefore may not meet the technical requirements of the directive. Should this evaluation kit not meet the specifications indicated in the EVM User's Guide, the kit may be returned within 30 days from the date of delivery for a full refund. THE FOREGOING WARRANTY IS THE EXCLUSIVE WARRANTY MADE BY SELLER TO BUYER AND IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED, IMPLIED, OR STATUTORY, INCLUDING ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE. The user assumes all responsibility and liability for proper and safe handling of the goods. Further, the user indemnifies TI from all claims arising from the handling or use of the goods. Please be aware that the products received may not be regulatory compliant or agency certified (FCC, UL, CE, etc.). Due to the open construction of the product, it is the user's responsibility to take any and all appropriate precautions with regard to electrostatic discharge. EXCEPT TO THE EXTENT OF THE INDEMNITY SET FORTH ABOVE, NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES. TI currently deals with a variety of customers for products, and therefore our arrangement with the user is not exclusive. TI assumes no liability for applications assistance, customer product design, software performance, or infringement of patents or services described herein. Please read the EVM User's Guide and, specifically, the EVM Warnings and Restrictions notice in the EVM User's Guide prior to handling the product. This notice contains important safety information about temperatures and voltages. For further safety concerns, please contact the TI application engineer. Persons handling the product must have electronics training and observe good laboratory practice standards. No license is granted under any patent right or other intellectual property right of TI covering or relating to any machine, process, or combination in which such TI products or services might be or are used. Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright * 2001, Texas Instruments Incorporated EVM WARNINGS AND RESTRICTIONS It is important to operate this EVM within the input voltage range of +5V and the output voltage range of +5V. Exceeding the specified input range may cause unexpected operation and/or irreversible damage to the EVM. If there are questions concerning the input range, please contact a TI field representative prior to connecting the input power. Applying loads outside of the specified output range may result in unintended operation and/or possible permanent damage to the EVM. Please consult the EVM User's Guide prior to connecting any load to the EVM output. If there is uncertainty as to the load specification, please contact a TI field representative. During normal operation, some circuit components may have case temperatures greater than 60C. The EVM is designed to operate properly with certain components above 60C as long as the input and output ranges are maintained. These components include but are not limited to linear regulators, switching transistors, pass transistors, and current sense resistors. These types of devices can be identified using the EVM schematic located in the EVM User's Guide. When placing measurement probes near these devices during operation, please be aware that these devices may be very warm to the touch. Mailing Address: Texas Instruments Post Office Box 655303 Dallas, Texas 75265 Copyright * 2001, Texas Instruments Incorporated Preface Read This First About This Manual This user's guide describes the function and operation of the AMC7820 Analog Monitoring and Control circuit evaluation module. This manual will help you quickly set up the evaluation board and its accompanying software so that you may rapidly test and evaluate the AMC7820. A complete circuit description, as well as a schematic diagram and bill of materials, is included. How to Use This Manual This manual begins with an introductory chapter that describes the EVM and what it can do. If you're anxious to set things up and start testing, we suggest you read at least the first two chapters. These two chapters introduce you to the board and how to set it up to start working with it. Later chapters go into more detail on the board's design and how to access its many features. Information About Cautions and Warnings This book may contain cautions. This is an example of a caution statement. CAUTION A caution statement describes a situation that could potentially damage your software or equipment. The information in a caution is provided for your protection. Please read each caution carefully. ii Related Documentation From Texas Instruments Related Documentation From Texas Instruments Data Sheets AMC7820 SN74AHC244 REG711EA Literature Number SBAS231 SCLS226 SBVS027 If You Need Assistance If you have questions about this or other Texas Instruments data converter evaluation modules, feel free to e-mail the data converter application team at dataconvapps@list.ti.com. Include the product name in the subject heading. FCC Warning This equipment is intended for use in a laboratory test environment only. It generates, uses, and can radiate radio frequency energy and has not been tested for compliance with the limits of computing devices pursuant to subpart J of part 15 of FCC rules, which are designed to provide reasonable protection against radio frequency interference. Operation of this equipment in other environments may cause interference with radio communications, in which case the user at his own expense will be required to take whatever measures may be required to correct this interference. Trademarks Windows is a trademark of Microsoft Corporation. SPI is a registered trademark of Motorola. iii Contents Read This First ......................................................................................................................... ii About This Manual ........................................................................................................................................... ii How To Use This Manual ................................................................................................................................ ii Information About Cautions and Warnings ..................................................................................................... ii Related Documentation From Texas Instruments .......................................................................................... iii If You Need Assistance .................................................................................................................................. iii FCC Warning .................................................................................................................................................. iii Trademarks ..................................................................................................................................................... iii Contents ................................................................................................................................... iv Figures ...................................................................................................................................... v Tables ........................................................................................................................................ v Introduction ........................................................................................................................... 1-1 1.1 1.2 1.3 1.4 1.5 1.6 Device Characteristics ........................................................................................................................... EVM Block Diagram .............................................................................................................................. Analog Inputs/Outputs ........................................................................................................................... Prototyping Area .................................................................................................................................... Power Requirements ............................................................................................................................. Computer Requirements ........................................................................................................................ 1-2 1-2 1-3 1-3 1-4 1-4 Getting Started ...................................................................................................................... 2-1 2.1 Unpacking the EVM ............................................................................................................................... 2-2 2.2 Default Configuration ............................................................................................................................. 2-2 2.3 Quick Start ............................................................................................................................................. 2-2 Operation ............................................................................................................................... 3-1 3.1 Jumpers ................................................................................................................................................. 3-2 3.1.1 DC/DC Converter .......................................................................................................................................... 3-2 3.2 I/O Connectors and Signals .................................................................................................................. 3-2 3.2.1 3.2.2 3.2.3 3.2.4 3.2.5 Parallel Port Connector ................................................................................................................................. External SPI Connector ................................................................................................................................. Power Connectors ......................................................................................................................................... External Reference Connector ...................................................................................................................... Thermistor Input Connector .......................................................................................................................... 3-2 3-3 3-3 3-3 3-3 3.3 Circuit Description .................................................................................................................................. 3-4 3.3.1 SPI Interface .................................................................................................................................................. 3-4 3.3.2 DC/DC Converter .......................................................................................................................................... 3-4 3.4 Program Description .............................................................................................................................. 3-4 3.4.1 Configuration and Control ............................................................................................................................. 3-4 3.4.2 D/A Converters .............................................................................................................................................. 3-6 3.4.3 A/D Converters .............................................................................................................................................. 3-7 Physical Description............................................................................................................. 4-1 4.1 Schematic ................................................................................................................................................................. 4-2 4.2 Component Locations ............................................................................................................................................... 4-3 4.3 Bill of Materials ......................................................................................................................................................... 4-4 iv Figures Figures Figure Figure Figure Figure Figure Figure 1. 2. 3. 4. 5. 6. AMC7820-EVM Block Diagram .................................................................. 1-2 Main Screen with Configuration/Status Display Selected ..................... 2-3 Configuration and Control Screen ........................................................... 3-5 D/A Converter Screen ................................................................................ 3-6 A/D Converter Scope Mode ....................................................................... 3-7 A/D Converter Data Mode .......................................................................... 3-7 Tables Table Table Table Table Table Table Table Table 1. 2. 3. 4. 5. 6. 7. 8. Default Configuration Settings.................................................................. 2-2 Configuration/Status Register Startup Values ........................................ 2-3 Jumper/Function Reference ...................................................................... 3-2 Parallel Port Connector.............................................................................. 3-2 External SPI Connector.............................................................................. 3-3 Power Connectors ...................................................................................... 3-3 External Reference Connector .................................................................. 3-3 Thermistor Input Connector ...................................................................... 3-3 v Chapter 1 Introduction The AMC7820 is a complete analog monitoring and control unit, which includes an 8-channel, 12-bit Analog-to-Digital (A/D) converter, three 12-bit Digital-to-Analog (D/A) converters, nine operational amplifiers, an internal 2.5V reference, and an SPITM serial interface. The evaluation board for this multifunction device, the AMC7820-EVM, is designed to ease the digital interface to the AMC7820 by connecting to a personal computer running easy-to-use software which allows total access to the AMC7820's various control functions. A large prototype area on the board provides space to connect circuitry to the AMC7820 and connections to configure the internal components. Topic Page Device Characteristics ........................................................................................................... 1-2 EVM Block Diagram ................................................................................................................ 1-2 Analog Inputs/Outputs ........................................................................................................... 1-3 Prototyping Area ..................................................................................................................... 1-3 Power Requirements .............................................................................................................. 1-4 Computer Requirements ........................................................................................................ 1-4 1-1 Introduction 1.1 Device Characteristics The AMC7820-EVM supports the AMC7820, which is soldered onto the EVM. The AMC7820's 8-channel A/D converter, three D/A converters, voltage reference, and nine operational amplifiers are all available for connection to the sizeable prototyping area on the board. Connectors are provided for the three power supplies needed by the AMC7820, as well as for a thermistor input and external reference input. An onboard 3V to 5V DC/DC converter can create the 5V analog supply needed by the AMC7820 if an external 5V supply is not available. 1.2 EVM Block Diagram Figure 1 shows a block diagram of the AMC7820-EVM. Figure 1. AMC7820-EVM Block Diagram. J1 PC Parallel Port Interface J2 External SPI J5 AVDD J3 DVDD 20 42 36 48 47 J4 BVDD Buffer SS SCLK MISO MOSI RESET 41 38 39 37 40 46 35 34 33 32 31 30 29 28 44 45 J7 Thermistor Input ISET R2 AMC7820 26 25 24 23 22 21 20 17 16 27 19 43 J6 Ext Ref OPA7_IN+ OPA7_OUT OPA7_IN- CH2 CH3 CH4 CH5 OPA1_IN- OPA1_OUT OPA1_IN+ SW1_OUT REF_OUT_2.5V OPA3_IN+ OPA3_OUT OPA3_IN- DAC1_OUT DAC1_OUT_SET DAC2_OUT_SET DAC2_OUT OPA4_IN+ OPA4_OUT OPA4_IN- OPA5_IN+ OPA5_OUT OPA5_IN+ OPA2_IN+ OPA2_OUT OPA2_IN- DAC0_OUT_SET DAC0_OUT OPA6_IN+ OPA6_OUT OPA6_IN- T_SENSOR_VOLTAGE SW2_OUT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 Breadboard 1-2 Introduction The digital control interface is either through the PC parallel port, or an external SPI bus. The PC parallel port can be disabled, allowing the external SPI bus to control the AMC7820. When using the PC parallel port, the digital interface voltage is 5V; when the external SPI bus is used, the digital interface voltage may be 5V or 3V. Power supplies are to be provided to the AMC7820-EVM through external connectors from an external, user-supplied laboratory power supply. AVDD and DVDD must be supplied at +5V, while BVDD can range from +2.7V to +5V. A thermistor can be connected to the AMC7820 through a terminal block. The thermistor is driven by a current source on the AMC7820, which is derived from the reference and set by the ISET resistor. The ISET resistor (see Figure 1) is identified as R2 on the AMC7820-EVM, and is socketed on the EVM so that the user can change its value. All the remaining pins of the AMC7820 (i.e., all the analog inputs and outputs) are brought out to a large prototype area on the AMC7820-EVM, so that external connections and circuitry can be made in any manner the user wishes. 1.3 Analog Inputs/Outputs The analog inputs and outputs of the AMC7820 are available on the prototyping area and are identified on the silkscreen. These include the op amps, A/D converter inputs, and D/A converter outputs. Note that the direct inputs to the A/D converter (CH2-CH5) are not buffered inside the AMC7820, and so should connect only to extremely-low impedance sources, or should be buffered externally. An external reference may be provided to the AMC7820 through J6. This reference voltage must remain within the specifications of the AMC7820. Consult the AMC7820 data sheet (SBAS231) at www.ti.com for these and other device specifications. The AMC7820 connects to a thermistor through J7. The nominal value of this thermistor is typically 10k. Since the AMC7820's A/D converter runs at 100kHz, and must scan through eight channels, each channel's effective conversion time is 80s. This means that each channel's effective sampling rate is 12.5kHz. Input signals above 6.25kHz, therefore, would result in aliasing, unless external anti-aliasing filters are provided. The voltage range of all the analog inputs and outputs of the AMC7820 are from 0V to 5V. Note that the D/A converters' outputs may be configured to range from 0V to VREF or from 0V to 2VREF. See the AMC7820 data sheet for details on the operating ranges of the analog inputs and outputs. 1.4 Prototyping Area The large prototype area of the AMC7820 provides plenty of room for external circuitry to be connected to the AMC7820. Every analog signal from the AMC7820 (except for the reference and thermistor connections, which are available on J6 and J7) is brought out to the edge of the prototype area. Five holes at each signal point are connected together to allow several connection points for external circuitry. Six large areas of copper are available for use as heatsinks for power devices. These copper areas are isolated from all other signals. 1-3 Introduction 1.5 Power Requirements The AMC7820 requires an analog supply voltage (AVDD) of 5V, a digital supply voltage (DVDD) of 5V, and an interface supply voltage (BVDD) that can range from 2.7V to 5.5V. The user should provide power-supply voltages from a lab-quality power supply. DVDD is provided on J3, AVDD is provided on J5, and BVDD is provided on J4. If a single 3.3V supply is used (connected to BVDD) to simulate the user's system supply, the onboard DC/DC converter can generate AVDD and DVDD if JMP1 is removed and JMP2 and JMP3 are installed. 1.6 Computer Requirements The AMC7820-EVM software is designed to run on a PC running any Windows(R) platform (Windows 95, 98, NT, 2000, etc). Minimum System Requirements: * IBM-Compatible 486 PC or Higher * Windows 95, 98, 2000, or NT4.0 * 32MB RAM Minimum * 20MB Available Hard Disk Space * CD-ROM Drive * Available Parallel Port 1-4 Chapter 2 Getting Started This chapter will guide you through unpacking the EVM and setting it up so you can begin working with it immediately. Topic Page Unpacking the EVM ................................................................................................................ 2-2 Default Configuration ............................................................................................................. 2-2 Quick Start ............................................................................................................................... 2-2 2-1 Getting Started 2.1 Unpacking the EVM After unpacking the AMC7820-EVM, check to make sure you received all the material that should be in the box. The EVM kit should include the following: * AMC7820-EVM Board, PWB 6432813 * CD-ROM, 6437057 * IEEE1284 25-Pin Parallel Cable If any of these components are missing, contact Texas Instruments at dataconvapps@list.ti.com for a replacement. 2.2 Default Configuration The AMC7820-EVM is a simple board and the only configuration details needed are the settings of the three jumpers and the value of R2, the resistor that sets the thermistor current. The default settings for these items are shown in Table 1. When you unpack your AMC7820-EVM, make sure that your board is initially configured as shown here. Table 1. Default Configuration Settings. Board Identifier Description Default Setting JMP1 JMP2 JMP3 R2 DC/DC Converter Disable AVDD = Onboard 5V DVDD = Onboard 5V Thermistor Current Set Installed Not Installed Not Installed 100k 2.3 Quick Start Once the AMC7820-EVM has been unpacked from its shipping container, and you have verified that the board is configured as shown in Table 1, it can be connected to power supplies. Connect wires from the terminal blocks J3, J4, and J5 to a +5V laboratory power supply. Make sure to observe correct polarity; the polarity for each terminal block is marked on the printed circuit board. Do not turn on the power supply at this time. If a thermistor is available, connect it to terminal block J7. Connect the IEEE-1284 cable to your PC, but do not connect it to the AMC7820-EVM board yet. Place the CD-ROM into your PC's CD-ROM drive. Locate the Setup program on the disk, and run it. The Setup program will install the AMC7820-EVM software on your PC. Note that if you are running a Windows platform that is NT-based, you will need administrator privileges to install the software. Follow the installer's instructions. When the installation is complete, turn on the power supply, and then connect the parallel port cable to the AMC7820-EVM. Once these connections have been made, launch the AMC7820-EVM software on your PC. The software should automatically determine the parallel port where the AMC7820-EVM is connected. If the board is found, the screen shown in Figure 2 will appear. 2-2 Getting Started Figure 2. Main Screen with Configuration/Status Display Selected. On this screen the Configuration/Status register bits are displayed. These bits should be as shown in Table 2. Table 2. Configuration/Status Register Startup Values. RST POL1 POL2 TSC1 TSC2 1 0 1 0 1 If these bits are not as shown in Table 2, you will have an error message before Figure 2 is displayed. Generally, if this happens, a communication problem exists. Check the cables and connections and make sure they are sound. Make sure that your power is on. Correct any problems and restart the program. 2-3 Chapter 3 Operation This chapter describes each function of the AMC7820-EVM and how to use the accompanying software to control and use the AMC7820. Topic Page Jumpers ................................................................................................................................... 3-2 I/O Connectors and Signals .................................................................................................. 3-2 Circuit Descriptions ................................................................................................................ 3-4 Program Description .............................................................................................................. 3-4 3-1 Operation 3.1 Jumpers Table 3 shows the function of each jumper on the EVM: Table 3. Jumper/Function Reference. Reference Designator Setting Function Subsection JMP1 Installed Open DC/DC Converter Disabled DC/DC Converter Enabled 3.1.1 3.1.1 JMP2 Installed Open AVDD Supplied by DC/DC Converter AVDD Supplied Through J5 3.1.1 3.1.1 JMP3 Installed Open DVDD Supplied by DC/DC Converter DVDD Supplied Through J3 3.1.1 3.1.1 3.1.1 DC/DC Converter The AMC7820-EVM has an onboard DC/DC converter designed to take 3.3V supplied through the BVDD terminal block, J4, and step it up to 5V to supply the analog and digital supply voltages. This feature is provided to illustrate how to use the AMC7820 in a system that only has a 3.3V power supply available. To enable the DC/DC converter, JMP1 should be removed and JMP2 and JMP3 installed. If the DC/DC converter is not used, JMP1 should be installed to disable the charge pump and minimize system noise. 3.2 I/O Connectors and Signals The various connectors on the AMC7820-EVM are described in this section. 3.2.1 Parallel Port Connector The connector for use with the PC parallel port is described in Table 4. This connector provides a means of communicating with the PC through an IEEE-1284 cable. Table 4. Parallel Port Connector. Reference Designator J1 3-2 Description Digital communication port between the AMC7820-EVM and a host PC. Pin Number Signal Name Function 1 EVM_ENABLE Enables the SPI bus control from the PC. 2 SS Slave Select for SPI bus. 3 SCLK Serial Clock for SPI bus. 4 MOSI Master Out, Slave In data line for SPI bus. Data travels to the AMC7820 over this line. 5 NC Not Connected 6 NC Not Connected 7 RESET 8-14 NC 15 MISO 16-17 NC 18-25 GND Reset line for the AMC7820. Not Connected Master In, Slave Out data line for SPI bus. Data travels from the AMC7820 over this line. Not Connected Ground Operation 3.2.2 External SPI Connector If the SPI bus is not controlled from the PC, it may be controlled through J2. The user might connect an external microprocessor or DSP to the AMC7820-EVM through this connector. Table 5. External SPI Connector. Reference Designator J2 Description Digital communication port between the AMC7820-EVM and an external processor. Pin Number Signal Name 1 RESET Function Reset line for the AMC7820. 3 SS Slave Select for SPI bus. 5 SCLK Serial Clock for SPI bus. 7 MOSI Master Out, Slave In data line for SPI bus. Data travels to the AMC7820 over this line. 9 MISO Master In, Slave Out data line for SPI bus. Data travels from the AMC7820 over this line. 2, 4, 6, 8, 10 GND Ground 3.2.3 Power Connectors Table 6. Power Connectors. Reference Designator Name J3 J4 J5 DVDD IN BVDD IN AVDD IN Description Digital (+5V) supply for the AMC7820. Digital I/O supply (3.3V-5V) for the AMC7820. Analog (+5V) supply for the AMC7820. 3.2.4 External Reference Connector Table 7. External Reference Connector. Reference Designator Name J6 EXT REF IN Description External reference input. 3.2.5 Thermistor Input Connector Table 8. Thermistor Input Connector. Reference Designator Name J7 THERMISTOR INPUT Description Connection for the thermistor input to the AMC7820. 3-3 Operation 3.3 Circuit Description The AMC7820-EVM consists of two circuits: the SPI interface and the DC/DC converter. The board consists primarily of breadboard area around the AMC7820. 3.3.1 SPI Interface The SPI interface to the AMC7820 can be controlled from two sources: the external SPI header, J2, or from the PC parallel port, J1. The PC parallel port connection is buffered through U1. U1's outputs are enabled only when pin 1 of U1 is LOW. This pin is pulled HIGH by R1, so that if no parallel port is connected, U1's outputs are tri-stated, allowing the external SPI bus to drive the AMC7820. When the PC parallel port is connected, the PC software will pull pin 1 of the parallel port (which is connected to pin1 of U1) LOW in order to enable the PC to control the SPI bus. Do not drive the external SPI bus when the PC parallel port is connected. Disconnect the PC parallel port cable from the AMC7820-EVM if you want to use the external SPI bus. CAUTION 3.3.2 DC/DC Converter In order to supply the AVDD and DVDD supplies from a 3.3V input on BVDD, the DC/DC converter circuit around U3 will boost the 3.3V input to 5V. U3 is enabled when ENABLE pin 2, is HIGH. R3 pulls this pin HIGH when JMP1 is not installed. When JMP1 is installed, the ENABLE pin is held LOW and the DC/DC converter will not operate. This helps reduce noise on the board when this feature is not needed. With JMP1 removed, 5V will appear on the output of U3 (pin 8). JMP2 and JMP3 should be installed to connect this 5V to AVDD and DVDD. 3.4 Program Description After having installed the software for the AMC7820-EVM as described in section 2.3, you may begin using it to evaluate and develop with the AMC7820. 3.4.1 Configuration and Control The program's interface is a simple, three-tab interface. Clicking on a tab will take you to the functions associated with that tab. The default tab that the program begins on is the Configuration and Control tab (see Figure 3). 3-4 Operation Figure 3. Configuration and Control Screen. This screen gives you access to the Configuration/Status register and the Shutdown register. You may also reset the AMC7820 from this screen. 3.4.1.1 Reset The Reset section, in the lower left hand corner of this screen, allows you to reset the AMC7820 by writing the correct code to the AMC7820's Reset register. Pressing the Write to Reset Register button will cause the AMC7820's registers to be returned to their default states. 3.4.1.2 Shutdown The Shutdown section of this screen lets you determine if SW1 and SW2 are disabled. This is done by writing the AMC7820's Shutdown register. If the checkbox is checked, the corresponding switch inside the AMC7820 is placed in its disabled state. Refer to the AMC7820 data sheet for more information on these switches and their function. 3.4.1.3 Configuration/Status This part of the screen allows you to see the bits in the AMC7820's Configuration/Status register. When the program is started, this register is read and its value displayed here. To read the register at any time, simply press the Read button and the program will read the current data out of the AMC7820. To change the bit settings, you may either use the radio buttons below the bit display to set specific modes of operation, or you may simply type the bit values into the fields displayed. Anytime a change is made, the change is NOT written to the AMC7820 device until the Write button is pressed. This allows you to see the effects of changes in the bit patterns without actually changing the configuration of the part until you are certain you have what you want. 3-5 Operation 3.4.2 D/A Converters This screen allows you to control the D/A converters in the AMC7820. You may read and write the D/A register values and specify or display these values in either hexadecimal format or in volts, as shown in Figure 4. Figure 4. D/A Converter Screen. 3.4.2.1 DAC0, DAC1, DAC2 These controls enable you to write a value to the D/A converters and read that value back. To set a D/A converter's output level, type the value into the box in the units you have chosen in the Display Units--either Hex or Volts. The value is not written to the D/A converter until you push the Write button. Pressing the Read button will cause the program to read the D/A converter register and display its value. The checkbox in this section tells the program how you have configured the hardware-- is the DACx_OUT_SET pin grounded? If so, then the D/A converter's output range is from 0V to 2VREF, whereas if it is not grounded, the range is 0V to VREF. These are the two typical cases; if you have external circuitry that changes these nominal gains, the program cannot take that into account for you directly. 3.4.2.2 VREF This section of the D/A converter screen allows you to specify the reference voltage you are using. Typically, this will be 2.5V from the internal reference of the AMC7820. However, if you supply an external reference, your voltage may be different and you may enter it here so that voltage calculations shown on this screen are correct. 3.4.2.3 Display Units You may select whether to display the D/A converter values as hexadecimal numbers (Hex) or voltage (Volts). If voltage is chosen, the voltage shown will be determined by the value of the reference voltage specified in the VREF section, and the value of the DACx_OUT_SET checkbox associated with each D/A converter. See the D/A converter section for more information. 3-6 Operation 3.4.3 A/D Converter This screen, shown in Figure 5, displays the readings from the onboard 8-channel A/D converter. Figure 5. A/D Converter Scope Mode. This screen gives you the option of viewing the converted data either in a Scope mode, as shown in Figure 5, or in Data mode. In Scope mode, all 8 channels of the A/D converter are displayed in a graphical format. Data mode displays a listing of the most recent samples, as shown in Figure 6. Figure 6. A/D Converter Data Mode. The data values are shown in volts, hexadecimal, and binary units. 3-7 Chapter 4 Physical Description Topic Page Schematic ................................................................................................................................ 4-2 Component Locations ............................................................................................................ 4-3 Bill of Materials ....................................................................................................................... 4-4 4-1 THERMISTOR INPUT DVDD PC PARALLEL PORT BVDD J7 C6 2.2F 2 1 JMP1 2 3 VOUT 5 4 PGND GND VIN ENABLE 6 7 9 7 5 3 2 4 6 8 2 GND A1 A2 A3 A4 10 A1 A2 A3 A4 G VCC Y1 Y2 Y3 Y4 G Y1 Y2 Y3 Y4 REG711EA-5 8 U3 BVDD 20 NOTE: C5, C6, and C7 must be ceramic X7R capacitors. Connect this ground point directly to pin 43 of U2. 1 2 R3 2.7k C5 0.22F CPUMP+ J2 11 13 15 17 19 18 16 14 12 C7 10F 1 JMP3 2 EXTERNAL SPI 2 4 6 8 10 AVDD 1 JMP3 1 3 5 7 9 J1 1 14 2 15 3 16 4 17 5 18 6 19 7 20 8 21 9 22 10 23 11 24 12 25 13 CPUMP- 1F 2 DVDD R2 RES_SKT C1 C2 1F DVDD 37 38 39 40 41 42 43 44 45 46 47 48 1 BVDD 2 1 AVDD 2 J5 AVDD IN 1 SCLK MOSI MISO SS BVDD DVDD DGND THERM_I_OUT ISET_RESISTOR OPA7_IN- OPA7_OUT OPA7_IN+ OPA3_OUT OPA3_IN- DAC1_OUT DAC1_OUT_SET DAC2_OUT_SET AVDD AGND DAC2_OUT OPA4_IN+ OPA4_OUT OPA4_IN- OPA5_IN+ 24 23 22 21 20 19 18 17 16 15 14 13 C3 1F C4 2 1F 1 J6 EXT_REF IN Analog and Digital ground should be connected together as a ground plane on layout. Connections to the ground pins of voltage connectors should be made directly from the connectors to the pins, so that the "mecca" of the grounds is at the part. 2 J4 BVDD IN 36 35 34 33 32 31 30 29 28 27 26 25 RESET CH2 CH3 CH4 CH5 OPA1_IN- OPA1_OUT OPA1_IN+ SW1_OUT EXT_REF_IN REF_OUT_2.5V OPA3_IN+ SW2_OUT T_SENSOR_VOLTAGE OPA6_IN- OPA6_OUT OPA6_IN+ DAC0_OUT DAC0_OUT_SET OPA2_IN- OPA2_OUT OPA2_IN+ OPA5_IN- OPA5_OUT 1 2 3 4 5 6 7 8 9 10 11 12 J3 DVDD IN AVDD BVDD DVDD BREADBOARD AREA Physical Description 4.1 Schematic 4-2 J2 J1 14 1 DGND DGND J3 DVDD J4 BVDD EXT SPI R1 C5 U2 C6 U3 C7 JMP3 JMP2 AMC7820EVM JMP1 R3 C1 U1 C2 C3 J5 J6 THERM IN LD 9 EXT REF IN AGND 2 1 C4 R2 OPA3+ OPA3 OUT OPA3- DAC1 OUT OUT SET1 OUT SET2 DAC2 OUT OPA4+ OPA4 OUT OPA4- OPA5+ OPA5 OUT OPA5- OPA2+ OPA2 OUT OPA2- DAC0 SET DAC0 OUT OPA6+ OPA6 OUT OPA5- SEN5 V SW2 OUT OPA7+ OPA7 OUT OPA7- AGND AGND AVDD AGND BVDD DGND DVDD DGND DGND CH2 CH3 CH4 CH5 OPA1- OPA1 OUT OPA1+ SW1 OUT EXT REF IN REF OUT AGND 25 13 4-3 AVDD AGND J7 Physical Description 4.2 Component Locations 643213 PWB Texas Instruments Physical Description 4.3 Bill of Materials REFERENCE ITEM NO. VALUE DESIGNATORS QTY 1 0.22F C5 1 2 1F C1-C4 4 3 2.2F C6 1 4 10F C7 1 5 6 7 8 9 2.7k J1 J3-J7 J2 JMP1-JMP3 R3 1 5 1 3 1 10 4.7k R1 1 11 12 13 14 15 R2 U1 U2 U3 NA 2 1 1 1 3 16 NA 4 17 NA 4 MFG MFG'S PART NUMBER DESCRIPTION Panasonic ECJ-3VB1E224K Cap 0.22F 25V 10% Ceramic Chip 1206 X7R or Alternate Panasonic ECJ-2VF1C105Z Cap 1F 16V 20% Ceramic Chip 0805 or Alternate Panasonic ECJ-3YB1C225K Cap 2.2F 16V 10% Ceramic Chip 1206 X7R or Alternate Panasonic ECJ-4YB1C106K Cap 10F 16V 10% Ceramic Chip 1210 X5R or Alternate AMP Incorporated 747842-4 DB25 Right-Angle Female Conn w/Board Locks On Shore Technology ED120/2DS 2 Contact Screw Terminal Blocks Samtec TSW-105-07-L-D 10-Pin Dual-Row Header (5x2) Samtec TSW-102-07-L-S 2-Pin Single-Row Header (2x1) Panasonic ERJ8GEYJ272V Resistor, 2.7k 1/8W 5% 1206 SMD or Alternate Panasonic ERJ8GEYJ472V Resistor, 4.7k 1/8W 5% 1206 SMD or Alternate AMP Incorporated 50863-5 Miniature Spring Socket Texas Instruments SN74AHC244PWR Octal Buffers/Drivers with 3-State Outputs Texas Instruments AMC7820 Analog Interface Texas Instruments REG711EA-5 50mA Switched-Cap DC/DC Converter Samtec SNT-100-BK-TH Shorting Jumper or Alternate Keystone Electronics 1808 1/4" x 0.625 Hex 4-40 Threaded Standoff or Alternate Building Fasteners PMS 440 0050 PH Pan Head Machine Screws 4-40 x 1/2" Phillips or Alternate Document Control Number 6432611 Revision A 4-4