Datasheet

General Troubleshooting
Problem: Software reports it cannot find the inter-
face circuit.
• Is the interface circuit power LED lit?
• Is the USB cable connected?
• Has Windows plug-and-play detected the board?
Bring up Control Panel->System->Device
Manager, and look at what device nodes are indi-
cated for USB. If there is an Unknown device node
attached to the USB, delete it—this forces plug-
and-play to try again.
• Are jumper JU1 and headers J1 and J2 properly
configured for USB operation? See Tables 2 and 3.
Detailed Description of Hardware
The MAX5422 EV kit is an assembled and tested PCB
that evaluates the MAX5422 256-tap, nonvolatile, linear
digital potentiometer. The MAX5422 has an end-to-end
resistance of 50kΩ and the wiper can be programmed
to one of 256 tap positions. The MAX5422 features an
internal, nonvolatile memory (EEPROM) used to store
the wiper position for initialization during power-up. The
MAX5422 EV kit provides an on-board SPI-compatible
serial interface to program the MAX5422.
The EV kit uses a MAX5422 IC in an 8-pin TDFN pack-
age on a proven two-layer PCB design. The MAX5422
EV kit provides two options to power the MAX5422 IC. It
can operate from the 3.3V supply generated from the
USB interface circuit, or from a user-supplied 2.7V to
5.25V external DC power supply. The logic level trans-
lators (U7, U8) provide proper SPI-interface operation
when using a 2.7V to 5.25V external power supply.
Evaluates: MAX5422/MAX5423/MAX5424
MAX5422 Evaluation Kit
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Figure 3. Simple Low-Level 3-Wire Interface