X9418 Xicor, X9418 Datasheet - Page 8

• Manufacturer Part Number: X9418
• Description: Dual Digitally Controlled Potentiometers
• Manufacturer: Xicor

X9418
DETAILED OPERATION
Both XDCP potentiometers share the serial interface
and share a common architecture. Each potentiometer
has a Wiper Counter Register and four Data Registers.
A detailed discussion of the register organization and
array operation follows.
Wiper Counter Register
The X9418 contains two 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
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 X9418 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.
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.
REV 1.1.5 7/23/02
potentiometer
has
four
nonvolatile
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Data
Register Descriptions
Data Registers, (6-Bit), Nonvolatile
Four 6-bit Data Registers for each XDCP. (eight 6-bit
registers in total).
– {D5~D0}: These bits are for general purpose not
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)
volatile 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 0.
The contents of the WCR can be loaded from any of
the other Data Register or directly. The contents of
the WCR can be saved in a DR.
WP5
NV
D5
V
WP4
NV
D4
V
Characteristics subject to change without notice.
WP3
NV
D3
V
WP2
NV
D2
V
WP1
NV
D1
V
(LSB)
(LSB)
WP0
NV
D0
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V