The MAX5471/MAX5472/MAX5474/MAX5475 contain a
resistor array with 31 resistive elements (Figures 2 and
3). The MAX5471/MAX5474 have a total end-to-end
resistance of 50kΩ, and the MAX5472/MAX5475 have
an end-to-end resistance of 100kΩ. The MAX5471/
MAX5472 wiper is connected to the high terminal, and
the low terminal is internally connected to ground, making
the device a variable resistor. The MAX5474/
MAX5475 allow access to the high, low, and wiper terminals
for a standard voltage-divider configuration.
The wiper is moved among the 32 tap points through a
simple 3-wire interface. Nonvolatile memory allows the
wiper position to be stored and recalled to the same
point upon power-up.
Digital Interface
Logic inputs CS, U/D, and INC control the wiper position
and store it in nonvolatile memory (see the Truth
Table). The chip-select (CS) input enables the serial
interface when low and disables the interface when
high. The position of the wiper is stored when CS transitions
from low to high and INC is high (see the Storing
Wiper Position section).