X9430 Datasheet, PDF (4/21 Pages) Xicor Inc. – Dual Digitally Controlled Potentiometer (XDCP™) with Operational Amplifier

X9430
Potentiometer/Array Description
The X9430 is comprised of two resistor arrays and two
operational amplifiers. Each array contains 63 discrete
resistive segments that are connected in series. The
physical ends of each array are equivalent to the fixed
terminals of a mechanical potentiometer (R_H and R_L).
At both ends of each array and between each resistor
segment is a CMOS switch connected to the wiper
(R_W) output. Within each individual array only one
switch may be turned on at a time. These switches are
controlled by a volatile wiper counter register (WCR).
The six bits of the WCR are decoded to select, and
enable, one of sixty-four switches.
The WCR may be written directly, or it can be changed
by transferring the contents of one of four associated
data registers into the WCR. These data registers and
the WCR can be read and written by the host system.
Operational Amplifier
The voltage operational amplifiers are CMOS rail-to-
rail output general purpose amplifiers. They are
designed to operate from dual (±) power supplies. The
amplifiers may be configured like any standard ampli-
fier. All pins are externally available to allow connec-
tion with the potentiometers or as stand alone
amplifiers.
HOLD V_CC
(DR0 - DR3)_{0,1 WCR0,1}
CS
SCK
SO
Control and
Memory
WCR0
SI
A1
WCR1
A0
+
(DR0 - DR3)_0,1
–
WP V_SS
V_{H (0,1)}
V_{L (0,1)}
V_{W (0,1)}
V_{INV (0,1)}
V_{N (0,1)}
V_{OUT (0,1)}
Detailed Block Diagram
(One of 2 Circuits)
Write in Process
The contents of the data registers are saved to nonvol-
atile memory when the CS pin goes from LOW to
HIGH after a complete write sequence is received by
the device. The progress of this internal write opera-
tion can be monitored by a write in process bit (WIP).
The WIP bit is read with a read status command.
INSTRUCTIONS AND PROGRAMMING
Identification (ID) Byte
The first byte sent to the X9430 from the host, follow-
ing a CS going HIGH to LOW, is called the identifica-
tion byte. The most significant four bits of the slave
address are a device type identifier, for the X9430 this
is fixed as 0101[B] (refer to Figure 1).
4
FN8198.0
March 11, 2005