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| 19-0398; Rev 1; 7/95 MAX197 Evaluation Kit _______________General Description The MAX197 evaluation system (EV system) is a complete, low-cost, 8-channel data-acquisition system consisting of a MAX197 evaluation kit (EV kit) and a Maxim 80C32 or 68HC16 microcontroller (C) module. IBM PC compatible software provides a handy user interface to demonstrate the MAX197's many features. Source code is provided. The MAX197 EV kit requires a single +5V supply and includes optional input buffer amplifiers that operate with 15V supplies. The MAX197 EV kit and EV system evaluate both the MAX197 and the MAX199. To evaluate the MAX199, order a sample of the MAX199 along with the MAX197 EV kit. ____________________________Features o Proven PC Board Layout o Complete Evaluation System o Convenient Test Points Provided On-Board o Data Logging Software o Source Code Provided o Fully Assembled and Tested o User-Selected Microcontroller Module 80C32 or 68HC16 Evaluates: MAX197/MAX199 ______________Ordering Information PART MAX197EVKIT-DIP MAX197EVC16-DIP MAX197EVC32-DIP TEMP. RANGE 0C to +70C 0C to +70C 0C to +70C BOARD TYPE Through-Hole Through-Hole Through-Hole ____________MAX197 EVC16 System ___________________Component List QTY 1 1 DESCRIPTION MAX197 Evaluation Kit (MAX197EVKIT-DIP) 68HC16 C Module (68HC16MODULE-DIP) ____________MAX197 EVC32 System ____________________Component List QTY 1 1 DESCRIPTION MAX197 Evaluation Kit (MAX197EVKIT-DIP) 80C32 C Module (80C32MODULE-DIP) _____________________________________________________MAX197 EVC16 System 68HC16 Module MAX197 EV Kit ________________________________________________________________ Maxim Integrated Products 1 Call toll free 1-800-998-8800 for free samples or literature. MAX197 Evaluation Kit Evaluates: MAX197/MAX199 ___MAX197 EV Kit Component List DESIGNATION QTY C1, C8, C15, C16, C17 C2-C7, C9, C12, C13 C10, C14, C18 C11 J11 J15, J16 JU1 JU2 JU3, JU4 R1, R2, R3 U1 U2 U3, U4 5 0 3 1 1 2 1 1 0 0 1 1 2 DESCRIPTION 0.1F ceramic capacitors Open 10F tantalum capacitors 100pF ceramic capacitor 2 x 20 header 8-pin headers 2-pin header 3-pin header Open Open MAX197BCNI MAX874CPA 4.096V reference MXL1014CN quad op amps _______MAX197 Stand-Alone EV Kit The MAX197 EV kit provides a proven PC board layout to facilitate evaluation of the MAX197. It must be interfaced to appropriate timing signals for proper operation. Refer to the MAX197 data sheet for timing requirements. ___MAX197 EV System Quick Start 1) Copy the files from the distribution disk to your hard disk or to blank floppy disks. The MAX197 EV kit software should be in its own directory. The necessary files are in the root directory of the distribution disk, and the source code is in the SOURCE subdirectory. The SOURCE subdirectory is not required to operate the EV kit. 2) Carefully connect the boards together by aligning the 40-pin header of the MAX197 EV kit with the 40pin connector of the C module. Gently press them together. The two boards should be flush against each other. 3) Connect a +15V/-15V DC power supply to the OPAMP V+ / OPAMP V- inputs of the MAX197 EV kit. Connect the power supply's COMMON terminal to the kit's AGND pad. 4) Connect a 9V to 15V DC power source to the C module. The terminal block is located next to the on/off switch, in the upper right corner of the C module. Observe the polarity marked on the board. The same +15V supply that powers OPAMP V+ can be used to power the C module. 5) Connect a cable from the computer's serial port to the C module. If using a 9-pin serial port, use a straight-through, 9-pin female-to-male cable. If the only available serial port uses a 25-pin connector, a standard 25-pin to 9-pin adapter will be required. The EV kit software checks the modem status lines (CTS, DSR, DCD) to confirm that the correct port has been selected. 6) Start the MAX197 software on the IBM PC by setting the current directory to match the directory that contains the Maxim programs, and then type the program name, "MAX197". Do not turn off or disconnect the C module while the program is running; if you do, you will have to restart the program. 7) The program will ask which C module is being used and to which port it is connected. Press the space bar until the correct port is highlighted, and press C until the correct C module is highlighted. Press ENTER when both are correct. The MAX197 program will be in terminal emulation mode. 8) Turn on the power for the C module. The C module will display its logon banner and test its RAM. 9) Download and run the RAM resident program on the C module by pressing ALT+L (i.e., hold down the ALT key as you strike the L key). The program prompts you for the file name. Press the ENTER key to download and run the file. 10) Press ALT+C to switch to the Control Panel screen after the RAM resident program has been successfully downloaded. 11) Apply input signals to the CH0-CH7 inputs at the right edge of the MAX197 EV kit board. Observe the readout on the screen. Table 1 lists the commands available from the control-panel screen. 12) Before turning off power to the MAX197 EV kit, exit the program by pressing ALT+X. 2 _______________________________________________________________________________________ MAX197 Evaluation Kit __Detailed Description of Software Reading the MAX197 The EV kit reads the MAX197 using the algorithm shown in source code Listings 1a and 1b. When power is first applied, the MAX197 is in external clock mode. However, the initialization software reconfigures the MAX197 to internal clock mode. The EV kit software demonstrates the MAX197's many modes of operation. When writing your own applicationspecific software, one of the following simplified algorithms (shown in bold type) should be implemented. These algorithms show the options available using the power-down and acquisition mode control bits. Except where otherwise specified, ACQMOD = 0. When using an external reference, a power-up delay is not necessary. When using the MAX197's internal reference, allow time for the REF capacitor to charge at power-up and when exiting full power-down mode. For a complete description of all control bits, refer to the MAX197 data sheet. Internal acquisition mode, standby power-down between conversions: 1) Begin conversion by writing PD1 = 1, PD0 = 0. This powers up the MAX197, causing it to perform a conversion, then go into standby mode after conversion completes. 2) After the INT pin goes low, read the result from the MAX197. Internal acquisition mode, full power-down between conversions: 1) Power up the MAX197 by writing PD1 = 1, PD0 = 0 (standby). 2) Execute a power-up delay, to allow the reference capacitor time to recharge. 3) Begin conversion by writing PD1 = 1, PD0 = 1 (full power-down). 4) After the INT pin goes low, read the result from the MAX197. Internal acquisition mode, SHDN pin low between conversions: 1) Power up the MAX197 by setting the SHDN pin high. 2) Execute a power-up delay to allow the reference capacitor time to recharge. 3) Begin conversion by writing PD1 = 1, PD0 = 0 (standby). 4) After the INT pin goes low, read the 16-bit result from the MAX197. 5) Power down the MAX197 by setting the SHDN pin low. External acquisition mode, standby power-down between conversions: 1) Begin acquisition time by writing PD1 = 1, PD0 = 0 (standby), ACQMOD = 1. 2) Execute the acquisition time delay. 3) Begin conversion by writing PD1 = 1, PD0 = 0 (standby), ACQMOD = 0. 4) After the INT pin goes low, read the result from the MAX197. External acquisition mode, full power-down between conversions: 1) Power up the MAX197 by writing PD1 = 1, PD0 = 0 (standby). 2) Execute a power-up delay, to allow the reference capacitor time to recharge. 3) Begin acquisition time by writing PD1 = 1, PD0 = 0 (standby), ACQMOD = 1. 4) Execute the acquisition time delay. 5) Begin conversion by writing PD1 = 1, PD0 = 1 (full power-down), ACQMOD = 0. 6) After the INT pin goes low, read the result from the MAX197. External acquisition mode, SHDN pin low between conversions: 1) Power up the MAX197 by setting the SHDN pin high. 2) Execute a power-up delay, to allow the reference capacitor time to recharge. 3) Begin acquisition time by writing PD1 = 1, PD0 = 0 (standby), ACQMOD = 1. 4) Execute the acquisition time delay. 5) Begin conversion by writing PD1 = 1, PD0 = 0 (standby), ACQMOD = 0. 6) After the INT pin goes low, read the result from the MAX197. 7) Power down the MAX197 by setting the SHDN pin low. Evaluates: MAX197/MAX199 _______________________________________________________________________________________ 3 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Listing 1a. Using the 68HC16 to Read the MAX197 4 _______________________________________________________________________________________ MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Listing 1b. Using the 80C32 to Read the MAX197 _______________________________________________________________________________________ 5 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 ____________________68HC16 Module ____Typical Timing Characteristics SAMPLE RATE vs. DELAY BETWEEN SAMPLES (COMMAND "D") MAX197-01 ______________________80C32 Module ____Typical Timing Characteristics SAMPLE RATE vs. DELAY BETWEEN SAMPLES (COMMAND "D") MAX197-04 100,000 100,000 10,000 SAMPLE (sps) SAMPLE (sps) NO ACQUISITION DELAY NO POWER-UP DELAY SHDN = HIGH 10,000 1000 1000 100 NO ACQUISITION DELAY NO POWER-UP DELAY SHDN = HIGH 100 1 10 100 1k 10k 68HC16 "D" COMMAND VALUE 10 1 10 100 1k 10k 100k 80C32 "D" COMMAND VALUE EXTERNAL ACQUISITION TIME vs. USER-SELECTED INPUT VALUE (COMMAND "A") MAX197-02 EXTERNAL ACQUISITION TIME vs. USER-SELECTED INPUT VALUE (COMMAND "A") MAX197-05 10,000 EXTERNAL ACQUISITION TIME (s) 1000 EXTERNAL ACQUISITION TIME (s) 1000 100 100 10 1 10 100 1k 10k 68HC16 "A" COMMAND VALUE 10 1 10 100 1000 80C32 "A" COMMAND VALUE POWER-UP DELAY vs. USER-SELECTED INPUT VALUE (COMMAND "P") MAX197-03 POWER-UP DELAY vs. USER-SELECTED INPUT VALUE (COMMAND "P") MAX197-06 10,000 100,000 POWER-UP DELAY (s) POWER-UP DELAY (s) 1k 1000 10,000 100 1000 10 100 1 10 100 10k 68HC16 "P" COMMAND VALUE 10 1 10 100 1k 10k 100k 80C32 "P" COMMAND VALUE 6 _______________________________________________________________________________________ MAX197 Evaluation Kit Shutdown Power Cycling From the control panel, use the up/down arrow keys to select the power-down mode. STANDBY power cycling puts the MAX197 in standby mode between readings, and FULLPD turns off everything except the 2.5V bandgap reference. The MAX197 is always fully powered during conversions. The MAX197's shutdown pin can be used to put the device into FULLPD mode. When using FULLPD or SHDN, a power-up delay may be necessary to allow the reference buffer time to recharge. From the control panel, use the "P" command to set this power-on delay. The 68HC16 software allows delays between 68s and 6000s. The 80C32 software allows delays between 8s and 65535s. A value of 0 disables the delay. Refer to the Typical Timing Characteristics to see the relationship between the value selected on the corresponding power-up delay. High-Speed Data Sampling For sampling rates over 10sps, the S command can be used. Data can be collected from only one of the eight channels at a rate from 100sps up to 45ksps for the 68HC16 module (10sps to 10ksps for the 80C32 module). First, select the channel by pressing one of the number keys 0-7. Next, press F to specify the name of the file into which the samples should be written. If the file already exists, the screen will say "*** file already exists***". To begin collecting data, press B. After 1024 samples have been collected, the data is automatically uploaded to the host and stored in the sample file. Evaluates: MAX197/MAX199 Controlling the Sampling Rate The rate for high-speed sampling, data logging, and the oscilloscope demo mode (see Table 1, key "O") is controlled by the D (delay between samples) command. When used with the sample or oscilloscope demo commands, specify the approximate delay in microseconds by typing D, the approximate delay time, then "usec". Refer to the Typical Timing Characteristics to see the relationship between the value selected and the corresponding delay between samples. Due to code overhead, this delay is not perfectly linear, so timing should always be verified using an oscilloscope. The fast sampling screen and oscilloscope demo mode use delays on the order of 100s to 1000s. The 80C32 software supports delays between 24s and 73ms, but the 68HC16 software only supports delays between 68s and 6000s. When used with the slower data-logging command, specify the delay in seconds. This delay is defined as the time between two consecutive conversions. Low-Speed Data Logging The RS-232 serial link limits the data logging sample rate to no more than 10sps (samples per second). The data logging command can be used to write data to a user-specified file in plain comma-spaced-value text format. From the control panel screen, press L. If a log file is not already open, the software will ask for a file name. Only one log file is allowed per session. Once a log file has been opened, pressing L toggles data logging on or off. While data logging is enabled, the word "Logging" will flash on the screen. One complete line of data is written to the log file after all enabled channels have been sampled. The first line of the log file contains the column headings. Each subsequent line of the log file contains all eight channels, separated by commas. The values are written as raw decimal output codes or as scaled voltages, depending on which setting the control panel is currently displaying. Use the C and V commands to select the display format (see Table 1). F3, the log data marker command, can be used to sequentially tag different sections of the log file to indicate a change in setup or input conditions. Pressing F3 writes an extra entry at the end of the current line of the data log, which can be useful for indicating a change in setup or input conditions. Tare Command (software offset null) The tare command is used to compensate in software for the offset voltage. Connect the channel 0 input pin to ground (or, if driving with an op amp, connect the channel 0 op amp's input to ground instead). The "T" command measures the offset voltage on channel 0 and subtracts that offset from all subsequent readings on all channels. The tare command is canceled by pressing CTRL+T. _______________________________________________________________________________________ 7 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 _Detailed Description of Hardware Driving the Analog Inputs Select an op amp based on its settling time. A fast settling time is more important than a fast slew rate. Sites U3 and U4 on the EV kit are industry-standard quad op-amp pinouts in the voltage-follower configuration. When using a slow op amp, extend the acquisition time by using the "A" command in the control panel. The 68HC16 software allows acquisition times between 68s and 6000s. The 80C32 software allows acquisition times between 12s and 560s. A value of 0 disables the delay. For high sampling rates, a fast settling op amp such as Maxim's MXL1014 performs quite well. Refer to the Typical Timing Characteristics to see the relationship between the value selected and the corresponding external acquisition delay. For lower sampling rates, any quad 741 type op amp should be adequate. The LM348 is an inexpensive solution. For +5V single-supply systems, the MAX414 is recommended. The MAX197 EV kit software assumes a 4.096V reference voltage, unless otherwise specified. When using other reference values, the reference value must be specified when starting the program. For example, if the REFADJ pin is driven by a 2.048V reference, start the MAX197 software by typing: MAX197 REFADJ 2.048 Or, if the REFADJ pin is pulled high and REF is driven by a 3.00V reference, start the MAX197 software by typing: MAX197 REF 3.00 Using an External Clock Cut JU4 open. From the control panel, press F8 to select external clock mode. Apply the external clock to the EXTCLK input pad. Evaluating the MAX199 To evaluate the MAX199 using the MAX197 EV kit, replace U1 with a MAX199. Then, at the DOS prompt, start the MAX197 software by typing: MAX197 199 If the voltage reference is different than the default 4.096V, the MAX197 EV kit software should be informed. For example, if the REFADJ pin is driven by a 2.048V reference, start the MAX197 software by typing: MAX197 199 REFADJ 2.048 Or, if the REFADJ pin is pulled high and REF is driven by a 3.00V reference, start the MAX197 software by typing: MAX197 199 REF 3.00 Refer to the Changing the Reference Voltage section for an explanation of how REF and REFADJ interact. Changing the Reference Voltage The MAX197 can use either its internal reference or an external reference. On the EV kit, the internal reference has been disabled by pulling the REFADJ pin up to +5V (JU1) and driving the REF pin with a MAX874 4.096V reference (JU2). When driving the REF pin with an external reference, install a shunt at JU1 and place JU2 in the 1-2 position. When driving the REFADJ pin with an external reference, leave jumper JU1 open and place JU2 in the 2-3 position. For lowest component count, the MAX197's internal reference can be enabled by removing the shunts from JU1 and JU2. This enables the internal bandgap reference and the reference buffer, driving REF internally to 4.096V. For best results, install a 0.01F ceramic bypass capacitor near the REFADJ pin (C7 on the EV kit). 8 _______________________________________________________________________________________ MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Table 1. MAX197 EV Kit Commands KEY F1 0-7 C V D , P FUNCTION Choose input scale (bipolar 10V, unipolar 10V, bipolar 5V, unipolar 5V). The currently active scale is shown underneath the bar-graph display. Enable or disable the corresponding input channel 0, 1, 2, 3, 4, 5, 6, or 7. The EV kit software scans all selected channels. Display the input codes in decimal. Display the input voltages. Delay between samples. Delays longer than one second are handled by the IBM PC; otherwise, the C module handles the delay. Timing is approximate and should be verified with an oscilloscope. Select standby, fast power-down, SHDN power-down, or no power-down. Power-up delay. Timing is approximate and should be verified with an oscilloscope. Power-up delay is used regardless of which power-cycling mode is selected. In standby mode, power-up delay is not necessary and should be set to zero. External acquisition time for use with slow op amps. Timing is approximate and should be verified with an oscilloscope. The MAX197 is placed in standby mode during acquisition time. Internal clock mode. Timing is controlled by capacitor C11. JU4 should be closed when using this mode. External clock mode. Clock must be provided at EXTCLK input pad. JU4 should be cut apart when using this mode. Oscilloscope demo. Samples are collected and discarded as fast as possible. Observe waveforms and timing with an oscilloscope. Sample one of the eight inputs at high speed and upload to a user-specified file. The sampling rate is controlled by the P, A, and D delays. Due to program overhead, the O and S commands operate at different rates. Timing should be verified with an oscilloscope. Tare (offset voltage null). Assumes that channel 0 is connected to AGND. Measures the code at channel 0 and subtracts that value from all subsequent readings. Cancel the Tare (T) function. Enable or disable data logging. If the -L command line option is not specified, the L command prompts for a log file name. Write a marker into the data log file. (See the Low-Speed Data Logging section.) Switch back to terminal mode. Exit to DOS. A F7 F8 O S T CTRL+T L F3 ALT+T ALT+X _______________________________________________________________________________________ 9 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Table 2. Command-Line Options when Starting MAX197 Software COMMAND 1 2 MONO -Lfilename FUNCTION Default to COM1 part of the PC. Default to COM2 part of the PC. For use with monochrome or LCD display. Open file "filename" for data logging, and enable the data-logging commands. Specify the voltage at the REF pin (nominally 4.096V). Note that REF is an input or an output, depending on the state of the REFADJ pin. Refer to the MAX197 data sheet. Specify the voltage at the REFADJ pin (nominally 2.5V). Interprets the output codes for a MAX199 instead of a MAX197. Refer to the MAX199 data sheet. JU3 open closed JU4 open JU2 JU1 open 1-2 2-3 open closed Table 3. Jumper Settings on MAX197 EV Kit JUMPER STATE closed FUNCTION (Default) Disable internal bandgap reference; REF pin is an input. Enable internal bandgap reference; REF pin is 4.096V output. (Default) Connects external 4.096V reference (MAX874) to REF pin; JU1 must be closed. Connects external reference to REFADJ pin. REF = 4.096V output and REFADJ = 2.5V output (internal reference) (Default Trace) Current-sense jumper. The MAX197 draws its +5V supply through this trace. Do not operate kit with JU3 open. (Default Trace) Use C11 as the timing capacitor for the MAX197 internal clock mode. Use the EXTCLK input pad as clock input. REF vvv REFADJ vvv 199 10 ______________________________________________________________________________________ MAX197 Evaluation Kit Evaluates: MAX197/MAX199 U2 +5V 1 2 3 J12 EXTCLK C11 100pF JU4 JU3 +5V J1 +5V J9 REF 4 R2 1 R3 OPTIONAL REFERENCE TRIM CIRCUIT J8 C7 REFADJ 0.01F (OPTIONAL) AGND R1 AGND 3 JU2 2 AGND GND VIN VOUT MAX874 COMP 8 7 6 5 C15 0.1F C8 0.1F AGND JU1 TO DISABLE 2.5V BANDGAP REF J2 GND C10 10F C14 10F DGND C1 0.1F C18 10F U1 2 x 20 HEADER TO 68HC16 MODULE OR 80C32 MODULE J11-11 J11-10 J11-9 J11-15 J11-30 J11-26 J11-25 J11-24 J11-23 J11-22 J11-21 J11-20 J11-19 J11-27 AGND 1 2 3 4 5 6 7 8 9 10 11 12 13 14 AGND DGND VDD REF 28 27 26 25 24 23 22 21 20 19 18 17 16 15 C2 C3 C4 C5 MAX197 CLK CS WR RD HBEN SHDN D7 D6 D5 D4 D3 D2 D1 D0 2 1 U3A J17 3 CH7 6 7 U3B J18 5 9 J3 J4 J5 J6 J7 J10 J13 J14 DIRECT OR BUFFERED INPUTS 7 U4B 2 1 U4A J21 3 6 5 9 OPTIONAL INPUT BYPASS CAPACITORS 8 U4C J23 10 13 TEST POINTS 14 J16-1 J16-2 J16-3 J16-4 J16-5 J16-6 J16-7 J16-8 AGND C16 0.1F J25 OPAMP V+ OPAMPV+ C17 J26 OPAMP VOPAMPV0.1F OPAMPV+ OPAMPVU3 4 11 U4 4 11 U4D J24 12 CH0 CH1 CH3 14 U3D 13 J20 12 CH4 8 U3C J19 10 CH5 CH6 REF + ADJ INT CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0 AGND CH7 CH6 CH5 CH4 CH3 CH2 CH1 CH0 C6 C9 C12 C13 J22 CH2 J11-7 J11-8 J11-1 J11-2 J11-3 J11-4 DGND +5V DGND CS WR RD HBEN SHDN INT +5V J15-1 J15-2 J15-3 J15-4 J15-5 J15-6 J15-7 J15-8 D0 D1 D2 D3 D4 D5 D6 D7 Figure 1. MAX197 EV Kit Schematic ______________________________________________________________________________________ 11 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Figure 2. MAX197 EV Kit Component Placement Guide 12 ______________________________________________________________________________________ MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Figure 3. MAX197 EV Kit PC Board Layout--Component Side ______________________________________________________________________________________ 13 MAX197 Evaluation Kit Evaluates: MAX197/MAX199 Figure 4. MAX197 EV Kit PC Board Layout--Solder Side 14 ______________________________________________________________________________________ |
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