7) Apply input signals to the inputs labeled
CH1A–CH4A at the bottom edge of the MAX125/
MAX126 EV kit board. Observe the readout on the
screen.
Detailed Description of Software
The MAX125/MAX126 digitize up to four inputs from
either the A or the B input bank. Conversion time is
determined by the number of enabled inputs. The soft-
ware collects samples at a maximum throughput of
40ksps (one channel) and 26ksps (four channels). The
various program functions are grouped into dialog
boxes, which are accessible from the Window menu on
the main menu bar.
Keyboard Navigation
If a mouse or other pointing device is not available, use
the following keyboard shortcuts (Table 2):
• Press ALT+W to display the Window menu, and
then select a tool window.
• Press the TAB key to select controls within the
selected tool window.
• Activate buttons by pressing the spacebar.
• Use the up/down arrow keys for check boxes, radio
buttons, and combo boxes.
Scan Tool
You can automatically take readings at regular intervals
up to 10 samples per second from user-selected chan-
nels by selecting Scan Tool from the Window menu.
The “Channel Selection and Configuration” group con-
trols which channels will be scanned. The “Bipolar and
Differential” controls are disabled because the
MAX125/MAX126’s transfer function is bipolar.
The “Scan Rate” combo box controls the rate at which
measurements are made. Readings are displayed in
the “Recent Values” text area.
You may optionally record readings into a data-log file.
Click on the “New Log” button to begin or end data log-
ging. The “Log File Format” dialog box is displayed.
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 contains all enabled channels, separated by com-
mas, tabs, or spaces (previously selected in the “Log
File Format” dialog box). Once a log file has been
opened, it can be paused or resumed with the corre-
sponding Log menu commands. The program contin-
ues to write data to the log file until the “Stop Log”
button is clicked.
One-Shot Read Tool
The “One-Shot Read Tool” allows direct control of the
analog-to-digital converter (ADC) configuration. Select
the channel and mode of operation to update the
“Control Byte” display. Or, change the “Control Byte”
bits directly and observe the change in the “Channel
Selection” control. The “Read Now” button writes the
configuration information to the ADC and performs one
reading.
Power Cycling Tool
To reduce average supply current demand, the
MAX125/MAX126 can be shut down between conver-
sions. From the Window menu, select “Power Cycling
Tool.” The amount of power saved depends primarily
on how long the part is off between conversions.
Conversion accuracy depends on the power-up delay,
reference capacitor, and time in power-down. Adjust
the off-time with the “Delay Between Samples” com-
mand. Adjust the on-time with the “Power-Up Delay”
command.
Using an adequate power-up delay ensures that the
desired conversion accuracy is achieved during power-
cycling modes. The reference must be allowed enough
time to stabilize before the measurement is performed.
Start with zero power-up delay, and increase the delay
time until no further change in accuracy is observed. The
power-up delay requirement depends on the value of the
reference capacitor and the off-time (delay between
samples).
The MAX125/MAX126 EV kit software performs power-
up by writing a configuration word with the shutdown
bit cleared. After power-up, the power-up delay is exe-
cuted to allow time for the reference voltage to stabilize
so that an accurate measurement can be performed.
Evaluate: MAX125/MAX126
MAX125/MAX126 Evaluation
Systems/Evaluation Kits
_______________________________________________________________________________________ 3
Copies the image of the main window
onto the clipboard
ALT+PrintScreen
Clicks on the selected buttonSpacebar
System menu of child windowALT+minus
System menu of main program windowALT+space
Window menuALT+W
Selects next controlTAB
FUNCTIONKEY
Table 2. Keyboard-Navigation Shortcuts
