X9251 Datasheet, PDF (5/25 Pages) Xicor Inc. – Quad Digitally-Controlled (XDCP) Potentiometer

X9251
PIN DESCRIPTIONS
Bus Interface Pins
SERIAL OUTPUT (SO)
SO is a serial data output pin. During a read cycle,
data is shifted out on this pin. Data is clocked out by
the falling edge of the serial clock.
SERIAL INPUT (SI)
SI is the serial data input pin. All opcodes, byte
addresses and data to be written to the device
registers are input on this pin. Data is latched by the
rising edge of the serial clock.
SERIAL CLOCK (SCK)
The SCK input is used to clock data into and out of the
X9251.
HOLD (HOLD)
HOLD is used in conjunction with the CS pin to select
the device. Once the part is selected and a serial
sequence is underway, HOLD may be used to pause
the serial communication with the controller without
resetting the serial sequence. To pause, HOLD must
be brought LOW while SCK is LOW. To resume
communication, HOLD is brought HIGH, again while
SCK is LOW. If the pause feature is not used, HOLD
should be held HIGH at all times.
DEVICE ADDRESS (A1–A0)
The address inputs are used to set the two least
significant bits of the slave address. A match in the
slave address serial data stream must be made with
the address input in order to initiate communication
with the X9251. Device pins A1-A0 must be tie to a
logic level which specify the internal address of the
device, see Figures 2, 3, 4, 5 and 6.
CHIP SELECT (CS)
When CS is HIGH, the X9251 is deselected and the
SO pin is at high impedance, and (unless an internal
write cycle is underway) the device is in the standby
state. CS LOW enables the X9251, placing it in the
active power mode. It should be noted that after a
power-up, a HIGH to LOW transition on CS is required
prior to the start of any operation.
Potentiometer Pins
R_H, R_L
The R_H and R_L pins are equivalent to the terminal
connections on a mechanical potentiometer. Since
there are 4 potentiometers, there are 4 sets of R_H and
R_L such that R_H0 and R_L0 are the terminals of DCP0
and so on.
R_W
The wiper pin are equivalent to the wiper terminal of a
mechanical potentiometer. Since there are 4
potentiometers, there are 4 sets of R_W such that R_W0
is the terminals of DCP0 and so on.
Supply Pins
SYSTEM SUPPLY VOLTAGE (V_CC) AND SUPPLY GROUND (V_SS)
The V_CC pin is the system supply voltage. The V_SS pin
is the system ground.
Other Pins
NO CONNECT
No connect pins should be left floating. This pins are
used for Xicor manufacturing and testing purposes.
HARDWARE WRITE PROTECT INPUT (WP)
The WP pin when LOW prevents non-volatile writes to
the Data Registers.
REV 1.3.3 2/10/04
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Characteristics subject to change without notice. 5 of 25