MAX5478EVKIT Maxim Integrated, MAX5478EVKIT Datasheet - Page 5

• Manufacturer Part Number: MAX5478EVKIT
• Description: Digital Potentiometer ICs Evaluation Kit/Evaluation System for the MAX5477/MAX5478/MAX5479
• Manufacturer: Maxim Integrated

Specifications of MAX5478EVKIT

• Resistance: 50 kOhms
• Number Of Pots: Dual
• Taps Per Pot: 256
• Wiper Memory: Non Volatile
• Digital Interface: Serial (2-Wire, I2C)
• Operating Supply Voltage: 5 V
• Supply Current: 15 uA
• Supply Voltage - Max: 5.25 V
• Supply Voltage - Min: 2.7 V

Note: Words in boldface are user-selectable features in
the software.
The user interface (shown in Figure 1) is easy to operate.
Use the mouse or press the tab key to navigate through
the GUI controls. The correct I
erated to update the internal memory registers of the
MAX5478 when any of these controls are used.
The software divides EV kit functions into logical blocks.
The Interface box indicates the Device Address, I
Clock Speed, EV kit Status, and the last write operation
Command Sent and Data Sent indicators. This data is
used to confirm proper device operation. The
Potentiometer A and Potentiometer B Control boxes
change the wiper position and transfer the data from the
volatile memory to the nonvolatile memory or vice-versa.
The MAX5478 EV kit software features additional func-
tions to simplify operation. Automatic Diagnostics con-
tinually probe the interface board and the MAX5478 EV
kit to make sure that all connections are maintained and
that all devices are working properly. These functions
create some activity on the I
Activity checkbox reduces I
MAX5478 EV kit to enable easy triggering of an oscillo-
scope. Checking the Wipers A and B checkbox issues
a command that sends the same data to both digital
potentiometers simultaneously and enables control of
both digital potentiometers together. The Factory Reset
button programs the volatile and nonvolatile memory of
both potentiometers to midscale (wiper position = 127).
The MAX5478 EV kit software automatically searches
for the CMODUSB command module and the MAX5478
EV kit during startup. The status indicator shows if the
interface board and the MAX5478 EV kit are opera-
tional. If the interface board is not found, verify that the
command module and the USB cable are connected
properly, power is applied to the EV kit, and click the
YES button on the retry-connection message box.
The nonfunctional GUI can be viewed by clicking the
NO button on the retry-connection message box when
attempting to start the software without the CMODUSB
command module being connected. Restart the soft-
ware with the command module and EV kit properly
connected for normal operation.
MAX5478 Evaluation Kit/Evaluation System
_______________________________________________________________________________________
Detailed Description
User-Interface Panel
2
2
C bus. The Silence I
C write operation is gen-
2
C bus activity to the
Software Startup
of Software
2
2
C
C
The trackbars in the Potentiometer A and B Control
boxes can be used to change the wiper position
between the H_ and L_ end points. Use the computer
mouse, arrow keys, or page-up/page-down keys to move
the trackbar between the 256 position points. The wiper
position can also be changed by entering the numerical
position (0 to 255) in the Volatile edit fields. A trackbar
or Volatile edit field change writes to the volatile memory
and the wiper position is updated with the data sent. The
data in the nonvolatile memory remains unchanged. The
wiper position is shown in the Volatile edit fields. The top
Volatile field shows the wiper position with respect to the
H_ end point and the bottom Volatile field shows the
wiper position with respect to the L_ end point. During
EV kit power-up, the data (wiper position) in the non-
volatile memory is transferred to the volatile memory and
the position of wipers A and B is updated. The Volatile
and Non-Volatile edit fields display “??” after initializing
the EV kit software because the MAX5478 does not
transmit data to the master.
The Non-Volatile edit fields can be used to program the
nonvolatile memory of the digital potentiometers. When
writing to the nonvolatile memory, the volatile memory
and the wiper position remain unchanged. The Non-
Volatile edit fields accept the numerical position from 0
to 255. The top Non-Volatile edit field shows the wiper
position with respect to the H_ end point and the bottom
Non-Volatile edit field shows the wiper position with
respect to the L_ end point.
The Potentiometer A and B Control boxes contain buttons
VREG->NVREG and NVREG->VREG that are used to
transfer data from the volatile memory to the nonvolatile
memory and the nonvolatile memory to the volatile mem-
ory. When the VREG->NVREG button is clicked, the data
present in the volatile memory is transferred to the non-
volatile memory. When the NVREG->VREG button is
clicked, the data present in the nonvolatile memory is
transferred to the volatile memory and the wiper posi-
tion is updated. When the VREG->NVREG and
NVREG->VREG buttons are clicked, the EV kit software
Data Sent indicator shows the last known data that is
being transferred. These commands do not send any
new data to the device because the commands trans-
ferred data already contained in the volatile or non-
volatile registers. See Table 3 for VREG and NVREG
behavior when WP is enabled and disabled.
Volatile/Nonvolatile Data Transfer
Nonvolatile Programming
Wipers A and B Position
5