General Description
Features
Ordering Information
MAX1202EVL11 System Component List
MAX1202 EV Kit Component List
Table i. MAX1202 EVKIT Parts List.
MAX1202 Stand-Alone EV Kit
MAX1202 EV System
Detailed Description of Software
Detailed Description of Hardware
Table 1. Jumper Functions
Table 2. Default Jumper Settings
The MAX1202 evaluation system (EV system) is a complete, eight-channel data-acquisition system consisting of a MAX1202 evaluation kit (EV kit) and a Maxim 3V 68L11D 68L11D microcontroller (æC) module. The MAX1202 is a low power +5V 8-channel 12-bit ADC that directly interfaces to 3V and 5V microprocessors. 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 the 68L11D æC Module has already been purchased with a previous Maxim EV system, or for custom use in other æC-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 operation, refer to the MAX147 data sheet.
* Proven PC Board Layout
* Complete Evaluation System
* Convenient Test Points Provided On Board
* Data-Logging Software
* 3V / 5V Logic Interface
* Fully Assembled and Tested
| PART | TEMP. RANGE | BOARD TYPE | |
| MAX1202EVKIT-DIP | 0*C to +70*C | Through-Hole | |
| MAX1202EVL11-DIP | 0*C to +70*C | Through-Hole |
| PART | QTY | DESCRIPTION | |
| MAX1202EVKIT-DIP | 1 | MAX1202 Evaluation Kit | |
| 68L11DMODULE | 1 | 68L11D *C Module |
Table i. MAX1202 EVKIT Parts List.
| DESIGNATION | QTY | DESCRIPTION | |
| C1-C8, C13 | 9 | 0.01uF ceramic capacitors | |
| C9-C11, C14, C15 | 5 | 0.1uF ceramic capacitors | |
| C12 | 1 | 4.7uF 10V tantalum capacitor | |
| J1 | 1 | 2x20 right angle socket | |
| JU1, JU2 | 2 | 3 pin jumper blocks | |
| JU3 | 1 | 2 pin jumper block | |
| JU4 | 0 | open | |
| R1-R8 | 8 | 300 ohm 5% resistors | |
| TP1 | 1 | 8 pin header | |
| U1 | 1 | Maxim MAX1202BCPP | |
| U1 | 1 | 20 pin socket | |
| U2 | 1 | Maxim ICL7660CPA | |
| U3 | 1 | 78L05 voltage regulator | |
| NONE | 1 | PC board | |
| NONE | 1 | Software disk, "MAX1202 EVALUATION KIT" |
The MAX1202 EV kit provides a proven PC board layout 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 your +5V analog supply between the "+5V" pad and the "GND" pad. Connect the "VLOGIC" pad to the micrprocessor's power supply. Set JU1 to the 2-3 position (VSS=- 5V) to allow input signals between +4 and -4 volts. See Table 1, Jumper Functions.
The MAX1202 EV system operates from a user-supplied 9V to 15V DC power supply. The Maxim 68L11D 3V æC board uses a MAX667 linear regulator to generate the 3V logic supply. The MAX1202 board uses a 78L05 linear regulator to generate its own 5 volt analog supply. No level translators are necessary because the MAX1202 VLogic pin is connected to the 3V logic supply.
1. Install the MAX1202 EV kit software on your computer by running the INSTALL.EXE program on the
floppy disk. The program files are copied and icons are created for them in the Windows 3.1 Program
Manager (or the Windows 95 Start Menu).
2. Check the jumper settings on the MAX1202 EV kit board. Refer to Table 1, Jumper Functions, and Table 2, Default Jumper Settings.
3. Carefully connect the boards by aligning the 40-pin header of the MAX1202 EV kit with the 40-pin
connector of the *C module. Gently press them together. The two boards should be flush against one
another.
4. Connect a 9V to 15V DC power source to the *C module at the terminal block located next to the
on/off switch, in the upper-right corner of the *C module. Observe the polarity marked on the board.
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 MAX1202 program by opening its icon in the Program Manager (or Start Menu).
7. The program will prompt you to connect the æC module and turn its power on. Slide SW1 to the "ON"
position. Select the correct serial port, and click OK. The program will automatically download
KIT1202.L11 to the module.
8. Apply input signals to the CH0-CH7 inputs at the right edge of the MAX1202 EV kit board. Observe
the readout on the screen.
To evaluate the MAX1203, turn off power to the kit, close JU3, and replace U1 with a MAX1203BCPP. Connect your external voltage reference to the "VREF" pad. No other hardware changes are necessary. Refer to "Changing the Reference Voltage".
To reduce average supply current demand, the MAX1202 can be shut down between conversions. From the "Power" menu, select "Full power-down" or "Fast power-down" mode. In fast power down mode (FASTPD), the 1.2V bandgap reference remains active. The amount of power savings depends primarily on how long the part is off between conversions. The accuracy of the conversions depends on the power-up delay, the reference capacitor, and the time in power-down. Adjust the off-time with the "Delay between samples" command. Adjust the on-time with the "Power-Up Delay" command.
Using an adequate power-up delay will ensure conversion accuracy during power cycling modes. The reference must be allowed enough time to stabilize before the measurement is performed. The "Set Power- Up Delay" command controls the power up delay. Increase the delay until no further change in accuracy is observed. The power-up delay requirement depends on the value of the VREF capacitor (C12) and the off- time (delay between samples).
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 digital logic powered down. After the power-up delay is complete, the reference voltage is correct and an accurate measurement may be performed.
The MAX1203 requires an external reference, so FULLPD mode may always be used, assuming that the external reference is always stable when measurements are performed. In this case, set the power-up delay to 0.
On the EV kit 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, the board must be modified (with the power off) by cutting jumper JU4 and connecting a current meter across JU4.
The RS-232 serial link limits the data-logging sample rate to no more than 10sps (samples per second). The "Log" menu can be used to write data to a user-specified file in comma-spaced-value text format. From the "Log" menu, select "Select Channels", and select the channels you wanna log. Next, pick 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.
For sampling rates over 10sps (samples per second), the high speed sampling commands can be used. Data can be collected from any single channel at high speed, using the commands on the "Sample" menu. First, select the channel and the number of samples. The sampling rate may be set by inserting a delay between samples, or choosing one of the preset sample rates. To begin collecting data, use the "Collect" command. After the samples have been collected, the data is automatically uploaded to the host and is graphed. The data can optionally be saved to a file.
The MAX1202 EV kit software assumes a 4.096V reference voltage, unless otherwise specified. The reference voltage assumption can be changed using "Set Reference Voltage" under the "MAX1202" menu.
If an external reference is used, the reference must have a temperature coefficient of 20ppm/øC or less to achieve accuracy to within four LSBs over the temperature range 0øC to 70øC. To achieve 12-bit accuracy over the 0øC to 70øC temperature range, the reference must have a temperature coefficient of 4ppm/øC or less.
U1, the MAX1202, is an 8 channel, 12 bit low power Analog to Digital converter with serial interface and shutdown. R1-R8 and C1-C8 act as anti-aliasing input filters. Analog supply rails are VDD, VSS, and GND. The digital interface is powered by the VLOGIC pin. The SHDN jumper controls hardware shutdown and also selects internal or external compensation mode. Refer to the MAX1202 data sheet.
U2, the ICL7660, is a charge pump that converts +5V to -5V.
U3, the 78L05, is a +5V linear regulator that provides a clean analog supply for the MAX1202.
The EV kit has an RC filter on each input with a time constant of approximately 3us (R = 300 ohms, C =
0. 01uF). Acquisition time with a 2MHz clock is 1.5us. The RC filter's settling time may increase the
acquisition time required for full accuracy when switching input channels.
| JUMPER | STATE | FUNCTION | |
| JU1 | 1-2 | VSS is tied to GND | |
| JU1 | 2-3 | VSS is tied to -5V | |
| JU1 | open | VSS must be supplied by the user | |
| JU2 | 1-2 | /SHDN\ is tied to GND | |
| JU2 | 2-3 | /SHDN\ is tied to +5V | |
| JU2 | open | /SHDN\ is floating | |
| JU3 | closed | REFADJ = +5V; VREF must be supplied by the user. | |
| JU3 | open | REFADJ = open; VREF pin = 4.096V internal reference. | |
| JU4 | closed (default trace) | Current-sense jumper. The MAX1202 draws its +5V analog supply through this trace. | |
| JU4 | open | Do not operate kit with JU4 open. |
| JUMPER | DEFAULT STATE | FUNCTION | |
| JU1 | 2-3 | VSS is tied to -5V | |
| JU2 | 2-3 | /SHDN\ is tied to +5V | |
| JU3 | open | REFADJ = open; VREF pin = 4.096V internal reference. | |
| JU4 | closed | The MAX1202 draws its +5V analog supply through this trace. |
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