Datasheet

© 2006 Microchip Technology Inc. DS21945E-page 39
MCP4021/2/3/4
5.2.10 WRITE WIPER SETTING TO
EEPROM AND DISABLE WiperLock
TECHNOLOGY
This mode is achieved by keeping the U/D pin static
(either at V
IL
or at V
IH
), while the CS pin is driven from
V
IH
to V
IHH
and then returned to V
IH
. When the falling
edge of the CS pin occurs (from V
IHH
to V
IH
), the wiper
value is written to EEPROM and the WiperLock
Technology is disabled (See Figure 5-10).
To ensure that “unexpected” transitions on the U/D
pin
do not cause the wiper setting to change, force the CS
pin to V
IH
as soon as possible (within device
specifications) after the CS
pin is forced to V
IHH
.
After the CS
pin is driven to V
IH
(from V
IHH
), all other
serial commands are ignored until the EEPROM write
cycle (t
WC
) completes.
FIGURE 5-10: Write Wiper Setting to EEPROM and Disable WiperLock™ Technology.
EEPROM
U/D
CS
Wiper
WiperLock™ Technology
X+4
X
X+4
WiperLock Technology Enable
WiperLock Technology Disable
V
IHH
V
IH
V
IL
V
IH
V
IH
t
WC