X9409 Xicor, X9409 Datasheet - Page 8

• Manufacturer Part Number: X9409
• Description: Quad Digitally Controlled Potentiometers
• Manufacturer: Xicor

X9409 – Preliminary Information
REV 1.6 1/30/03
DETAILED OPERATION
All XDCP potentiometers share the serial interface and
share a common architecture. Each potentiometer has
a Wiper Counter Register and 4 Data Registers. A
detailed discussion of the register organization and
array operation follows.
Wiper Counter Register
The X9409 contains four Wiper Counter Registers, one
for each XDCP potentiometer. The Wiper Counter
Register can be envisioned as a 6-bit parallel and serial
load counter with its outputs decoded to select one of
sixty-four switches along its resistor array. The contents
of the WCR can be altered in four ways: it may be
written directly by the host via the Write Wiper Counter
Register instruction (serial load); it may be written
indirectly by transferring the contents of one of the four
associated Data Registers via the XFR Data Register
instruction (parallel load); it can be modified one step at
a time by the Increment/ Decrement instruction. Finally,
it is loaded with the contents of its Data Register zero
(DR0) upon power-up.
The WCR is a volatile register; that is, its contents are
lost when the X9409 is powered-down. Although the
register is automatically loaded with the value in DR0
upon power-up, it should be noted this may be different
from the value present at power-down.
Data Registers
Each
Registers. These can be read or written directly by the
host and data can be transferred between any of the
four Data Registers and the Wiper Counter Register. It
should be noted all operations changing data in one of
these registers is a nonvolatile operation and will take a
maximum of 10ms.
potentiometer
has
four
nonvolatile
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Data
If the application does not require storage of multiple
settings for the potentiometer, these registers can be
used as regular memory locations that could possibly
store system parameters or user preference data.
Register Descriptions
Data Registers, (6-Bit), Nonvolatile:
Four 6-bit Data Registers for each XDCP. (sixteen 6-bit
registers in total).
– {D5~D0}: These bits are for general purpose not vol-
Wiper Counter Register, (6-Bit), Volatile:
One 6-bit Wiper Counter Register for each XDCP. (Four
6-bit registers in total.)
– {D5~D0}: These bits specify the wiper position of the
(MSB)
(MSB)
atile data storage or for storage of up to four different
wiper values. The contents of Data Register 0 are
automatically moved to the wiper counter register on
power-up.
respective XDCP. The Wiper Counter Register is
loaded on power-up by the value in Data Register R
The contents of the WCR can be loaded from any of
the other Data Register or directly by command. The
contents of the WCR can be saved in a DR.
WP5
NV
D5
V
WP4
D4
NV
V
Characteristics subject to change without notice.
WP3
NV
D3
V
WP2
NV
D2
V
WP1
NV
D1
V
(LSB)
(LSB)
WP0
NV
D0
V
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0
.