Datasheet

MCP4011/2/3/4
DS21978C-page 30 © 2006 Microchip Technology Inc.
5.2.1 INCREMENT
This mode is achieved by initializing the U/D pin to a
high state (V
IH
) prior to achieving a low state (V
IL
) on the
CS pin. Subsequent rising edges of the U/D pin
increment the wiper setting toward terminal A. This is
shown in Figure 5-1.
After the wiper is incremented to the desired position,
the CS
pin should be forced to V
IH
to ensure that
“unexpected” transitions on the U/D
pin do not cause
the wiper setting to increment. Driving the CS pin to V
IH
should occur as soon as possible (within device
specifications) after the last desired increment occurs.
When the device voltage falls below the RAM retention
voltage of the device, the wiper state may be corrupted.
When the device returns to the operating range, the
wiper will be loaded with the default POR wiper setting.
After the CS
pin is driven to V
IH
(from V
IL
), any other
serial command may immediately be entered.
FIGURE 5-1: Increment.
Note: The wiper value will not overflow. That is,
once the wiper value equals 0x3F,
subsequent increment commands are
ignored.
U/D
CS
Wiper
1 2 3 4
X+1
X
X+2 X+3 X+4
V
IH
V
IH
5
6
V
IL
V
IL