wms7121100s Winbond Electronics Corp America, wms7121100s Datasheet - Page 8

• Manufacturer Part Number: wms7121100s
• Description: Mixed Signal Winpot Digital Potentiomemter
• Manufacturer: Winbond Electronics Corp America

The WMS7120/7121 device has a 3-wire Up/Down Serial Interface consisting of CS , INC and U/ D
control signals. The key features of this interface include:
The wiper position can be changed either up or down by operating the CS , U/ D and INC control
signals.
When CS is LOW, the device is selected and the wiper can be moved by toggling the INC . As a
result, the wiper moves up when U/ D is HIGH and moves down when U/ D is LOW. The status of the
U/ D can be changed even though the CS remains LOW. This allows the system to enable the
device and then move the wiper position either up or down until the desired position is reached.
When the wiper is already at the lowest position, further Down operation won’t change the wiper
position. Similarly, when the wiper is at the highest position, further Up operation won’t change the
wiper position too.
The current wiper position can be automatically stored into the NVMEM0 each time the CS goes
from LOW to HIGH while the INC remains HIGH. Adversely, if the INC is LOW when the CS goes
HIGH, the wiper position cannot be stored. Meanwhile, the NVMEM0 content is automatically loaded
into the wiper during power on.
When the CS is held HIGH, the device enters into Standby mode and the wiper position cannot be
changed. Changing the CS to LOW exits the Standby mode and enables the device again.
The operating modes of Up/Down interface are summarized in the table below:
LOW to HIGH
LOW to HIGH
7.3. S
•
•
•
•
•
7.4. O
Note: x means don’t care
Enabling the device
Determining the moving direction of the wiper
Increment/Decrement operation on the wiper
Non-volatile storage of the present wiper position into the NVMEM0 for automatic recall at
power up
Entering into the standby mode
HIGH
LOW
LOW
CS
ERIAL
PERATION
D
ATA
O
I
VERVIEW
NTERFACE
HIGH
LOW
U/ D
x
x
x
HIGH to LOW
HIGH to LOW
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HIGH
LOW
INC
x
Store Current Wiper Position
No Store, Return to Standby
Move Wiper toward R
Move Wiper toward R
WMS7120 / 7121
Operation
Standby
A
B
/V
/V
A
B