Maxim Integrated MAX1202 User Manual

_____MAX1202 Stand-Alone EV 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 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 (VSS= -5V) to allow input sig­nals between ±4V (Table 1).

_______________General Description

The MAX1202 evaluation system (EV system) is a com­plete, 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 mod­ule 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.

____________________________Features

♦ 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

________________________________________________________________

Maxim Integrated Products

1

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

U2 1 Maxim ICL7660CPA
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

____________________Component List

MAX1202EVL11

___________System Component List

______________Ordering Information

For free samples & the latest literature: http://www.maxim-ic.com, or phone [phone]

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

1

QTY DESCRIPTION

MAX1202 Evaluation Kit

6811D MODULE

AVAILABLE

Evaluates: MAX1202/MAX1203

MAX1202 Evaluation Kit

2 _______________________________________________________________________________________

______________MAX1202 EV System

The MAX1202 EV system operates from a user­supplied 9V to 15V DC power supply. The Maxim
68L11D 3V µC board uses a MAX667 linear regulator to
generate the 3V logic supply. The MAX1202 board
uses a 78L05 linear regulator to generate its own 5V
analog supply. No level translators are necessary
because the MAX1202 VL pin is connected to the 3V
logic supply.

Quick Start

1) Install the MAX1202 EV kit software on your comput­er by running the

INSTALL.EXE

program on the flop­py disk. The Windows 3.1 Program Manager (or the
Windows 95 Start Menu) copies the program files
and creates icons for them.

2) Check the jumper settings on the EV board. Refer to
Tables 1 and 2.

3) Carefully connect the boards by aligning the EV kit’s
40-pin header with the µC module’s 40-pin connec­tor. Gently press them together. The two boards
should be flush against one another.

4) Connect a 9V to 15V DC power source to the µC
module at the terminal block located next to the
on/off switch, in the upper-right corner of the µC
module. Observe the polarity marked on the board.

5) Connect a cable from the computer’s serial port to
the µC 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 is 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 µC
module and turn its power on. Slide SW1 to the on
position. Select the correct serial port and click OK.
The program automatically downloads

KIT1202.L11

to the module.

8) Apply input signals to the CH0–CH7 inputs at the
right edge of the MAX1202 EV board. Observe the
readout on the screen.

Evaluating the MAX1203

To evaluate the MAX1203, turn off the power to the EV kit,
close JU3, and replace U1 with a MAX1203BCPP.
Connect the external voltage reference to the VREF
pad. No other hardware changes are necessary. Refer
to the section

Changing the Reference Voltage.

Table 1. Jumper Functions

∫

JUMPER STATE FUNCTION

1-2 VSStied to GND

Closed

(default trace)

Current-sense jumper. The
MAX1202 draws its +5V analog
supply through this trace.

2-3 VSStied to -5V

Open VSSmust be supplied by the user.

1-2

SHDN tied to GND; power-down

2-3

SHDN tied to +5V; internal com­pensation

Open

SHDN floating; external compen­sation

Closed

REFADJ = +5V; VREF must be
supplied by the user.

Open

REFADJ = open; VREF = 4.096V
internal reference (MAX1202)

Open Do not operate kit with JU4 open.

JUMPER

DEFAULT

STATE

FUNCTION

JU1 2-3 VSStied to -5V
JU2 2-3

SHDN tied to +5V

JU3 Open

REFADJ = open; VREF = 4.096V
internal reference (MAX1202)

JU4 Closed

The MAX1202 draws its +5V
analog supply through this trace.

JU1

JU2

JU3

JU4

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 refer­ence capacitor, and the time in power-down. Adjust off­time 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 require­ment 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 exter­nal 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 chan­nels 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 col­lected from any single channel at high speed, using the
commands on the “Sample” menu. First select the num­ber 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 collect­ed, 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 refer­ence voltage, unless otherwise specified. The refer­ence-voltage assumption can be changed using “Set
Reference Voltage” under the “Device” menu.

If an external reference is used, it must have a tempera­ture coefficient of 20ppm/°C or less to achieve accuracy
to within four LSBs over the 0°C to +70°C range. For 12­bit accuracy over this range, the reference must have a
temperature coefficient of 4ppm/°C or less.

Detailed Description

________________________of Hardware

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 VSS.

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 (τ) of approximately 3µs (R = 300Ω,

C = 0.01µF). The MAX1202’s acquisition time with a
2MHz clock is 1.5µs. 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

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