Datasheet

MCP4011/2/3/4
DS21978C-page 26 © 2006 Microchip Technology Inc.
3.6 Chip Select (CS)
The CS pin is the chip select input. Forcing the CS pin
to V
IL
enables the serial commands. These commands
can increment and decrement the wiper. Forcing the
CS pin to V
IHH
enables the high-voltage serial
commands. These commands can increment and
decrement the wiper and are compatibe with the
MCP402X devices. The wiper is saved to volatile
memory (RAM).
The CS
pin has an internal pull-up resistor. The resistor
will become “disabled” when the voltage on the CS pin
is below the V
IH
level. This means that when the CS pin
is “floating”, the CS pin will be pulled to the V
IH
level
(serial communication (the U/D pin) is ignored). And
when the CS
pin is driven low (V
IL
), the resistance
becomes very large to reduce the device current
consumption when serial commands are occurring.
See Figure 2-3 for additional information.
3.7 Increment/Decrement (U/D)
The U/D pin input is used to increment or decrement
the wiper on the digital potentiometer. An increment
moves the wiper one step toward terminal A, while a
decrement moves the wiper one step toward
terminal B.