wms7171 Winbond Electronics Corp America, wms7171 Datasheet - Page 7

• Manufacturer Part Number: wms7171
• Description: Non-volatile Digital Potentiometers With Up/down 3-wire Interface, 10kohm, 50kohm, 100kohm Resistance 100 Taps Without / With Output Buffer
• Manufacturer: Winbond Electronics Corp America

The WMS7170 device can operate as either a two-terminal variable resistor or a three-terminal
voltage divider without an output buffer. However, the WMS7171 can only operate in a three-terminal
voltage divider with an output buffer.
In the rheostat mode, the WMS7170 can be configured as a two-terminal resistive element, where one
terminal is connected to one end of the resistor (R
The moving direction of the wiper depends upon the setting of U/ D control signal. When the U/ D is
set to Up, then the wiper moves towards R
wiper moves towards R
signal from HIGH to LOW.
This configuration controls the resistance between the wiper and either end. The wiper resistance can
be adjusted by either changing the wiper position or loading a stored wiper position value from
NVMEM0 upon power up.
Additionally, the WMS7170 can also be configured as a voltage divider. With an input voltage applied
to one end (usually V
cannot exceed the V
to the wiper position with respect to the voltage difference between V
the wiper depends upon the setting of the U/ D control signal. When the U/ D is set to Up, then the
wiper moves towards V
V
LOW.
Nevertheless, the WMS7171 can only be configured as a voltage divider and operate similarly as the
WMS7170 device. The only difference is WMS7171 has an output buffer, but WMS7170 doesn’t have.
Besides, the resistance cannot be directly measured in this configuration.
The WMS7170/7171 has one NVMEM0 location available for storing the current wiper position via the
Up/Down serial interface. This stored value is automatically recalled and loaded into the tap register
upon power up.
B
. The wiper movement to either direction is controlled by toggling the INC signal from HIGH to
7. FUNCTIONAL DESCRIPTION
7.1. R
7.2. N
7.1.1. Rheostat Configuration
7.1.2. Divider Configuration
HEOSTAT
ON
-V
OLATILE
A
DD
A
ND
), the ground is connected to the other end (usually V
level or go below the V
A
B
. Conversely, when the U/ D is set to Down, then the wiper moves towards
. The wiper movement to either direction is controlled by toggling the INC
M
D
EMORY
IVIDER
O
(NVMEM0)
PERATIONS
A
. Conversely, when the U/ D is set to Down, then the
SS
- 7 -
level. The voltage on the wiper, V
A
or R
B
) and the other terminal is the wiper (R
A
Publication Release Date: July 2003
and V
WMS7170 / 7171
B
. The moving direction of
B
). These input voltages
W
, is proportional
Revision 1.0
W
).