MAX1202EVKIT MAXIM | Alldatasheet
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_____MAX1202 Stand-Alone EV Kit The MAX1202 EV kit provides a proven PC board lay- out to facilitate evaluation of the MAX1202. It must be interfaced to appropriate timing signals for proper operation. Refer to the MAX1202 data sheet for timing requirements. Cut JU4 and apply the +5V analog supply between the +5V pad and the pad marked GND. Connect the VLOGIC pad to the microprocessor's power supply. Set JU1 to the 2-3 position (V SS = -5V) to allow input sig- nals between ±4V (Table 1). The MAX1202 evaluation system (EV system) is a com- plete, 8-channel data-acquisition system consisting of a MAX1202 evaluation kit (EV kit) and a Maxim 3V 68L11D microcontroller (µC) module. The MAX1202 is a low-power, +5V, 8-channel, 12-bit analog-to-digital converter (ADC) that connects directly to 3V and 5V microprocessors (µPs). Windows 3.1™/ Windows 95™ software provides a handy user interface to exercise the MAX1202’s features. Order the EV system for comprehensive evaluation of the MAX1202 using a personal computer. Order the EV kit if you have already purchased the 68L11D µC mod- ule with a previous Maxim EV system, or for custom use in other µC-based systems. The MAX1202 EV kit and EV system can also be used to evaluate the MAX1203. Simply order a free sample of the MAX1203BCPP along with the MAX1202 EV kit. For 3V-only applications, refer to the MAX147 data sheet. ' Proven PC Board Layout ' Complete Evaluation System ' Convenient On-Board Test Points ' Data-Logging Software ' 3V/5V Logic Interface ' Fully Assembled and Tested Evaluates: MAX1202/MAX1203 MAX1202 Evaluation Kit 19-1197; Rev 0; 3/97 QTY DESCRIPTION C1–C8, C13 9 C9, C10, C11, C14, C15 5 C12 1 4.7µF, 10V tantalum capacitor J1 1 JU1, JU2 2 3-pin jumper blocks JU3 1 JU4 0 R1–R8 8 TP1 1 8-pin header
1 Maxim MAX1202BCPP
U3 1 78L05 voltage regulator 2 x 20 right-angle socket 0.1µF ceramic capacitors 0.01µF ceramic capacitors DESIGNATION 2-pin jumper block Open 300Ω , 5% resistors MAX1202EVL11 For free samples & the latest literature: http://www.maxim-ic.com, or phone 1-800-998-8800 None 1 PC board None 1 Software disk, “MAX1202 EVALUATION KIT” Windows is a registered trademark of Microsoft Corporation. U1 1 20-pin socket PART MAX1202EVKIT-DIP 0°C to +70°C TEMP. RANGE BOARD TYPE Through-Hole MAX1202EVL11-DIP 0°C to +70°C Through-Hole PART MAX1202EVKIT-DIP 68L11DMODULE 1 68L11D µC Module QTY DESCRIPTION MAX1202 Evaluation Kit 6811D MODULE AVAILABLE
should be flush against one another. module. Observe the polarity marked on the board. the Program Manager (or Start Menu). position. Select the correct serial port and click OK. close JU3, and replace U1 with a MAX1203BCPP. Changing the Reference Voltage. Table 1. Jumper Functions Open VSS must be supplied by the user. Open Do not operate kit with JU4 open. analog supply through this trace. Table 2. Default Jumper Settings
__Detailed Description of Software Shutdown Power Cycling The MAX1202 can be shut down between conversions to reduce average supply-current demand. From the “Power” menu, select full power-down (FULLPD) or fast power-down (FASTPD) mode. In fast power-down mode, the bandgap reference remains active. The amount of power saved depends primarily on how long the part is off between conversions. The conversion accuracy depends on the power-up delay, the refer - ence capacitor, and the time in power-down. Adjust off- time with the “Delay Between Samples” command. Adjust on-time with the “Power-Up Delay” command. Using an adequate power-up delay ensures conversion accuracy during power-cycling modes. The reference must be allowed enough time to stabilize before the measurement is performed. The “Power-Up Delay” command controls power-up delay. Increase the delay until accuracy is constant. The power-up delay require - ment depends on the off-time (delay between samples) and the value of the reference capacitor (C12). The MAX1202 EV kit software performs power-up by starting a conversion in FASTPD mode and discarding the reading. FASTPD mode turns on the reference, but leaves the MAX1202’s other circuitry powered down. An accurate reference-voltage measurement can be performed after the power-up delay is complete. The MAX1203 requires an external reference, so FULLPD mode can always be used, assuming the exter- nal reference is always stable when measurements are performed. In this case, set power-up delay to 0. Measuring Supply Current On the EV board, the MAX1202 draws all of its +5V analog power through jumper JU4, which is wired closed when the board is shipped from the factory. To measure the MAX1202’s supply current, modify the board (with the power off) by cutting jumper JU4 and connecting a current meter across JU4. Low-Speed Data Logging The RS-232 serial link limits the data-logging sample rate to no more than 10 samples/sec. The “Log” menu can be used to write data to a user-specified file in comma-spaced-value text format. From the “Log” menu, choose “Select Channels”, and select the chan - nels you want to log. Then choose the “New Log File” command from the “Log” menu. Once a log file has been opened, it can be paused or resumed with the “Pause” command. One complete line of data is written 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 enabled channels, separated by commas, tabs, or spaces. The program continues to write data to the log file until the “Done” command is selected from the “Log” menu. High-Speed Data Sampling The high-speed sampling commands can be used for sampling rates over 10 samples/sec. Data can be col - lected from any single channel at high speed, using the commands on the “Sample” menu. First select the num- ber of samples. Then set the sampling rate either by inserting a delay between samples, or by choosing one of the preset sample rates. Use the “Collect” command to begin collecting data. After the samples are collect - ed, the data is automatically uploaded to the host and graphed. Additionally, the data can be saved to a file. Changing the Reference Voltage The MAX1202 EV kit software assumes a 4.096V refer - ence voltage, unless otherwise specified. The refer - ence-voltage assumption can be changed using “Set Reference Voltage” under the “Device” menu. If an external reference is used, it must have a tempera- ture coefficient of 20ppm/° C or less to achieve accuracy to within four LSBs over the 0° C to +70° C range. For 12- bit accuracy over this range, the reference must have a temperature coefficient of 4ppm/° C or less. Detailed Description Components The MAX1202 (U1) is an 8-channel, 12-bit, low-power analog-to-digital converter (ADC) with serial interface and shutdown. R1–R8 and C1–C8 are anti-aliasing input filters. The analog supply rails are VDD, VSS, and GND. The digital interface is powered by the VL pin. The SHDN jumper controls hardware shutdown and selects internal/external-compensation mode. Refer to the MAX1202 data sheet for more information. The ICL7660 (U2) is a charge pump that converts +5V to -5V for V SS. The 78L05 (U3) is a +5V linear regulator that provides a clean analog supply for the MAX1202. Input Filtering The MAX1202 EV kit has an RC filter on each input with a time constant ( t) of approximately 3 µs (R = 300 Ω , C = 0.01 µF). The MAX1202’s acquisition time with a 2MHz clock is 1.5 µs. The RC filter’s settling time can increase the acquisition time required for full accuracy when switching input channels. Evaluates: MAX1202/MAX1203 MAX1202 Evaluation Kit
Figure 1. MAX1202 EV Kit Schematic
Evaluates: MAX1202/MAX1203 MAX1202 Evaluation Kit Listing 1. MAX1202 Pseudo-Code Example
Evaluates: MAX1202/MAX1203 MAX1202 Evaluation Kit Listing 2. Bit-Banging Substitute for SPI Port