19-0141; Rev. 2; 6/08
MAX186 Evaluation System/Evaluation Kit
Evaluates: MAX186
General Description
The MAX186 evaluation system (EV system) consists of
a MAX186 evaluation kit (EV kit) connected to a Maxim
80C32 microcontroller (µC) module. The unit connects
to an IBM-compatible personal computer running soft-
ware provided with the MAX186 EV kit. Both boards
come fully assembled and tested.
Using the EV system, the MAX186 input multiplexer can
be software-configured in a variety of single-ended or dif-
ferential modes with unipolar or bipolar input ranges. The
MAX186 can be evaluated with a V
SS
voltage of 0V or
-5V, selectable from the personal computer’s keyboard.
The EV system is also useful for evaluating the
MAX186’s shutdown feature. The MAX186 can be
operated in three states of readiness between conver-
sions. There are provisions for monitoring the supply
current in the different shutdown states, and for varying
the delay between conversions.
Order the EV system (MAX186EVSYS-DIP) for compre-
hensive evaluation of the MAX186 or MAX188 using a
personal computer. Order the EV kit (MAX186EVKIT-DIP)
if the 80C32 module (80C32MODULE-DIP) has already
been purchased with a previous Maxim EV system, or for
custom use in other µC-based systems. The MAX186 EV
kit can also perform limited evaluation on a stand-alone
basis (see the
MAX186 EV Kit Quick Start
section).
♦
12-Bit Resolution ADC
♦
Serial
µC
Interface
♦
Unipolar +4.096V or Bipolar -2.048V to +2.048V
Input Ranges
♦
Internal Reference Voltage
♦
Low Supply-Current Shutdown Mode
♦
Evaluates All Operating Modes
♦
Proven PCB Layout
♦
Prototyping Area Provided
♦
Digitizes 8 Analog Inputs
♦
Fully Assembled and Tested
Features
♦
Includes EV Kit and 80C32
µC
Module
Ordering Information
PART
MAX186EVSYS-DIP
MAX186EVKIT-DIP
80C32MODULE-DIP
TEMP RANGE
0°C to +70°C
0°C to +70°C
0°C to +70°C
BOARD TYPE
Through-Hole
Through-Hole
Through-Hole
EV System
________________________________________________________________ Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim's website at www.maxim-ic.com.
MAX186 Evaluation System/Evaluation Kit
Evaluates: MAX186
EV System Component List
QTY
1
1
DESCRIPTION
MAX186 evaluation kit (MAX186EVKIT-DIP)
80C32 µC module (80C32MODULE-DIP)
DESIGNATION
C1, C2,
C3, C4, C8
C6*
EV Kit Component List
QTY
5
1
4
8
8
1
1
1
1
1
1
1
1
4
1
1
1
DESCRIPTION
10µF 16V radial electrolytic
capacitors
22µF low-ESR radial electrolytic
capacitor
0.1µF ceramic capacitors
0.01µF ceramic capacitors
300Ω 5% resistors
10kΩ 9-resistor SIP
Maxim MAX186DCPP
Maxim ICL7660CPA
Maxim DG413DJ
Female 40-pin data connector
20-pin IC socket for U1
8-pin header
3.00in x 3.75in PCB
Rubber feet
MAX186 EV kit software on a
5 1/4in floppy disk
MAX186 data sheet
MAX186 EV kit manual
MAX186 EV System Quick Start
The MAX186 EV system includes a Maxim 80C32 module
and a MAX186 EV kit. The two connect through a 40-pin
data connector on adjoining edges of the boards. The EV
system then connects to an IBM-compatible computer
running software provided with the MAX186 EV kit.
The personal computer and the 80C32 module are con-
nected via a standard RS-232 serial communication
port. If the serial port on the personal computer has the
standard 9-pin connector, a straight through cable is
used to attach the board. Systems with a 25-pin serial
port connector need an adapter or adapter cable (D25
female to D9 male). Both the adapter and the cable are
available at most computer supply stores.
The steps for using the MAX186 EV system are outlined
as follows:
1) Visit www.maxim-ic.com/evkitsoftware to download
the latest version of the EV kit software. Save the EV
kit software to a temporary folder and uncompress
the file (if it is a .zip file).
2) Install the MAX186 EV kit software on your comput-
er by running the INSTALL.EXE program. The pro-
gram files are copied and icons are created for
them in the Windows
Start | Programs
menu.
3) Connect the MAX186 evaluation board to the 40-pin
data connector on the Maxim 80C32 module.
4) Connect an 8V to 16V source to the 2-pin power
connector on the 80C32 module. The positive lead
connects to the terminal marked VIN.
5) Connect a cable from the personal computer serial
connector to the 9-pin RS-232 connector on the
80C32 module.
6) Turn on the power to the 80C32 module. The switch
is located on one edge of the board. The LED indi-
cates power from the on-board regulator.
7) Start the MAX186 program by opening its icon in
the Windows
Start | Programs
menu.
C5, C7,
C9, C10
C11-C18
R1-R8
R9*
U1
U2
U3
J1
None
H1
None
None
None
None
None
*C6 and R9 are supplied with the kit but not mounted on the
PCB.
8) The 80C32 will transmit a logon message and RAM
test results when communications are initialized.
The MAX186 RAM resident program will then be
automatically downloaded.
9) Connect the analog inputs to the CH0-CH7 pads
and observe the readout on the screen.
MAX186 EV Kit Quick Start
This section applies only to use of the MAX186EVKIT-
DIP without the 80C32 module.
The MAX186 evaluation board can easily be configured
in the quick-look circuit of Figure 5 of the MAX186/
MAX188 data sheet. All of the necessary digital pins
are provided on the 8-pin header located along the bot-
tom edge of the board. Each pin function is indicated
by labels below the header.
2
_______________________________________________________________________________________
MAX186 Evaluation System/Evaluation Kit
1) Solder the 10-pin SIP resistor, provided with the kit,
in the R9 location on the EV kit board. The SIP resis-
tors act as pull-ups for the digital signals connected
to the 8-pin header. The marked end of R9 is pin 1.
2) Connect +5V and ground (GND) to the appropriate-
ly labeled pads on the evaluation board.
3) To operate the MAX186 in single-supply mode,
ground the header pin marked VSEL. Leaving the
pin open sets the MAX186 V
SS
pin to -5V (dual-sup-
ply operation).
4) Connect a clock signal (0.1MHz to 0.4MHz*) to the
header pin, labeled SCLK.
5) Ground the header pin, labeled
CS
.
6) Connect an analog input source to the channel 7
input pad, labeled CH7.
7) Connect an oscilloscope, as shown in Figure 5 of
the MAX186/MAX188 data sheet.
*
To run at clock frequencies up to 2MHz, an external
compensation capacitor must be connected to the
VREF pin. Install the 22µF capacitor supplied with the
kit in location C6, and cut the trace across jumper
JU2 to disable the MAX186 internal compensation.
P1.5
DOUT
Evaluates: MAX186
Table 1. Port 1 Bit Functions
BIT
P1.0
P1.1
P1.2
P1.3
P1.4
NAME
V
SS
SEL
SCLK
SHDN
–
SSTRB
FUNCTION
V
SS
select switches the MAX186 V
SS
pin between ground and -5V. Logic low,
V
SS
= 0V; logic high, V
SS
= -5V.
Serial clock for data transfer
Drives the MAX186
SHDN
pin. Cut
jumper JU2 to float the
SHDN
pin.
Not used
MAX186 SSTRB pin. Provides the busy
output during internal clock mode (see
MAX186/MAX188 data sheet).
MAX186 DOUT pin. Transfers conver-
sion data from the MAX186 to the
80C32.
MAX186
CS
pin. Enables serial com-
munications with the MAX186.
MAX186 DIN pin. Transfers data from
the 80C32 to the MAX186.
P1.6
CS
P1.7
DIN
Detailed Description
V
SS
Circuit
An ICL7660 +5V to -5V converter and a DG413 analog
switch (mounted on the MAX186 evaluation board) pro-
vide the means to switch the MAX186’s V
SS
voltage
between ground and -5V. The analog switch is not
required for most application circuits because the V
SS
voltage will be fixed at either -5V or ground. A negative
V
SS
supply is required only when the MAX186’s input is
expected to go below ground.
The ICL7660 provides a -5V source with minimal addi-
tional circuitry. The ICL7660 converter circuit on the
MAX186 EV kit is the standard circuit for +5V to -5V
conversion. Its 10mA output capacity is much more
than is needed by the MAX186, which requires only
50µA. The additional current is available for user cir-
cuits in the prototyping area. For applications where
the MAX186 is the only load, the 10µF capacitors may
be reduced to 0.1µF.
Serial Interface
The 80C32 and MAX186 communicate through the 8
bits of port 1 on the 80C32. Table 1 lists the function of
each bit. The 80C32 drives MAX186 input data on the
DIN bit and receives data from the MAX186 on the
DOUT bit. For the first eight clock cycles after chip-
select (
CS
) goes low, DIN data is clocked into the
MAX186 on the rising edge of the serial clock (SCLK)
signal. For the 12 data-output clock cycles, the
MAX186 updates DOUT data on the falling edge of
SCLK. See the MAX186 data sheet for complete infor-
mation concerning the serial interface; Figures 6-12 of
the MAX186/MAX188 data sheet are timing diagrams
for operating in the internal and external clock modes.
Note that the maximum conversion rate of the EV sys-
tem is limited to 5ksps, because of the speed limitation
of the 80C32. For evaluation at full speed, see the
MAX186 EV Kit Quick Start
section.
_______________________________________________________________________________________
3
MAX186 Evaluation System/Evaluation Kit
Evaluates: MAX186
The MAX186 digital signals are available on the 8-pin
header located on the bottom edge of the board. This
header provides convenient connections for scope
probes or a ribbon cable.
Jumper JU2 is in series with the
SHDN
pin of the
MAX186. Opening this jumper floats the
SHDN
pin, dis-
abling the internal compensation of the reference
buffer. The external compensation capacitor, C6, is
supplied with the kit but not mounted on the PCB. If you
wish to use external compensation, cut the trace across
JU2 and mount the 22µF capacitor, C6. The reference
settling delay must be increased. See the MAX186/
MAX188 data sheet for descriptions of internal and
external reference compensation.
Conversion Cycles
The MAX186 performs conversions on demand or at
preset intervals. The conversion sequence does not
vary with the two methods. If the device is in shutdown
mode, a dummy conversion brings it out of shutdown,
and the program delays to allow the reference voltage
to settle. Then, as many as eight conversions are per-
formed to collect data for a complete line of the screen
display. Finally, if shutdown mode is enabled, another
dummy conversion returns the MAX186 to the proper
shutdown state.
Evaluating External
Reference Voltages
The MAX186 can be operated with an external refer-
ence voltage if the internal reference is disabled.
Connecting the REFADJ pin to V
DD
will disable the
internal reference. Soldering a short piece of wire
across jumper JU3 will make this connection. The 22µF
capacitor should also be soldered into location C6
when using an external voltage. The reference voltage
is then applied to the pad labeled VREF.
To use the MAX188, which requires an external refer-
ence, install C6 and connect the reference source to
the VREF pad.
Jumper JU1 facilitates monitoring the MAX186 supply
current in the shutdown modes. The jumper allows the
insertion of a current meter in series with the MAX186
V
DD
supply. To monitor the current, cut the printed cir-
cuit trace between the two holes marked JU1. Then sol-
der two short leads in each hole and connect the amme-
ter. A short piece of wire can be soldered across the
jumper location to restore normal connections.
Shutdown Mode
The MAX186 has two shutdown levels. The FULL shut-
down mode completely disables the MAX186 reference
circuit and reduces supply current to 2µA. A delay of
300µs is required to activate from this shutdown state.
The delay must be greater when the external reference
compensation capacitor, C6, is installed. Be sure to set
the reference settling delay whenever the FULL shut-
down mode is used. Table 5 of the MAX186/MAX188
data sheet lists the reference settling times required for
different external capacitors.
The second shutdown level disables only the reference
output buffer. This drops the supply current to 30µA,
but requires a shorter delay (5µs with internal compen-
sation) between activation and conversion cycles. This
is referred to as the FAST shutdown mode.
On the MAX186 evaluation board, the
SHDN
pin (P1.2),
is programmed high so that it always enables the
MAX186 in normal operation. All modes are controlled
through software. In FAST or FULL shutdown mode, the
MAX186 is placed in shutdown between conversion
cycles and activated just before the conversions begin.
This reduces the average supply current but will
require a delay before the conversions. The
MAX186EVKIT Personal Computer Program
section has
information on varying the delay and controlling the
shutdown mode.
Analog Inputs
Each of the eight inputs has a 300Ω resistor in series.
These optional resistors were included as current-limiting
devices for input overvoltage conditions. There is also an
optional 0.01µF capacitor on each of the inputs. This pro-
vides the low source impedance required when the
channel is the low side of a differential input pair. The
input capacitors are not required on channels used as
single-ended inputs. Refer to the
Pseudo-Differential
Input
section of the data sheet.
4
_______________________________________________________________________________________
MAX186 Evaluation System/Evaluation Kit
Reference Adjustment
The MAX186 software assumes a reference voltage of
4.096V. This value is used for calculating the displayed
results after each conversion. The value can be altered
to reflect the exact reference voltage of the MAX186 or
to scale the displayed readings. Changing the indicated
value does not alter the MAX186’s reference voltage.
The MAX186’s internal 4.096V reference voltage can be
adjusted over a ±1.5% range by adding resistors R10
through R13, shown on the schematic. Refer to the
MAX186 data sheet for detailed information about the
reference voltage.
Saving Graphs to Disk
Data in the real-time graph and in sampled data graphs
may be saved to a file. Only the raw output codes are
saved, but voltages may be inferred, based on the ref-
erence voltage and the maximum code value.
Evaluates: MAX186
Scanning All Channels
To scan through all channels, select
SCAN
from the
INPUT
menu.
Reference Voltage
The evaluation software assumes a 4.096V reference
voltage, unless otherwise specified. Refer to the
MAX186 IC data sheet for more information. To override
this value, type the new reference voltage into the
Vref
edit box and click the
Set Vref
button.
Description of Software
The evaluation software’s main window controls the
active control word bits, serial clock speed, and sam-
ple rate. It displays the voltage and output code for
each active channel, as well as some statistics of the
input signal. A separate graph window shows the data
changing in real time. The update rate is limited to
about 10 samples per second due to COM port band-
width limitations.
RAM Resident Program
The 186RAM.MAX program is an 80C32 program that is
transferred from disk to the static RAM on the 80C32
module. It receives conversion commands from the
186EVKIT program running on the personal computer,
controls the conversion cycle, and returns the results. Its
operation is transparent to the user.
Controls
The control word is divided into several fields. To
change the active control word, drop down the appro-
priate field’s combo box and select the desired option.
EPROM Resident Program
In addition to the two programs supplied with the
MAX186 EV kit, a small 80C32 bootstrap program is
stored in the EPROM located on the 80C32 board. The
EPROM resident program initializes the 80C32, estab-
lishes communications over the RS-232 link, checks the
static RAM, and downloads the 186RAM program. Its
operation starts on power-up and whenever the reset
button is pressed. It transmits an identification banner
after receiving the first character and then tests the on-
board static RAM.
The last operation performed by the EPROM resident
program is downloading the 186RAM program and
storing it in the static RAM. Once the program is fully
loaded, control of the 80C32 is transferred to the RAM
resident 186RAM program.
Statistics
The
Minimum
and
Maximum
fields show the highest and
lowest readings acquired. The
Average
field shows a run-
ning mean based on the equation a
i
= (k)(x
i
) + (1 - k)
(a
i
-
1
). The
Clear
button resets the statistics. To remove
offset errors, first apply 0V to the active input channel,
clear statistics, acquire some samples, and then check
Tare.
This average offset voltage will now be subtracted
from all subsequent measurements.
Sampling
Choose the desired sampling rate (QSPI Clock), sam-
pling size (Sample! menu item), click
Begin Sampling!
(in Sample! pop-up window). Sample size is restricted
to a power of 2 to permit FFT processing once the data
is saved to a file. After the samples have been collect-
ed, the data is automatically uploaded to the host and
is graphed. Once displayed, the data can optionally be
saved to a file.
_______________________________________________________________________________________
5
Analogue and Mixed Signal
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