X9111 Datasheet, PDF (5/21 Pages) Xicor Inc. – Single Digitally-Controlled Potentiometer

X9111 – Preliminary Information
Figure 1. Detailed Potentiometer Block Diagram
Serial Data Path
Serial
RH
From Interface
Circuitry
Bus
Input
Register 0
Register 1
C
(DR0)
(DR1)
O
U
10
10 Parallel
Bus
Input
N
T
E
R
Register 2
(DR2)
Register 3
(DR3)
Wiper
D
Counter
E
Register
C
(WCR)
O
D
E
If WCR = 000[HEX] then R_W = R_L
If WCR = 3FF[HEX] then R_W = R_H
RL
RW
These switches are controlled by a Wiper Counter
Register (WCR). The 10-bits of the WCR (WCR[9:0])
are decoded to select, and enable, one of 1024
switches.
Wiper Counter Register (WCR)
The X9111 contains a Wiper Counter Register (see
Table 1) for the XDCP potentiometer. The WCR is
equivalent to a serial-in, parallel-out register/counter
with its outputs decoded to select one of 1024 switches
along its resistor array. The contents of the WCR can
be altered in one of three ways: (1) it may be written
directly by the host via the write Wiper Counter
Register instruction (serial load); (2) it may be written
indirectly by transferring the contents of one of four
associated Data Registers via the XFR Data Register;
(3) it is loaded with the contents of its Data Register
zero (DR0) upon power-up.
The Wiper Counter Register is a volatile register; that
is, its contents are lost when the X9111 is powered-
down. Although the register is automatically loaded
with the value in R0 upon power-up, this may be
different from the value present at power-down. Power-
up guidelines are recommended to ensure proper
loadings of the R0 value into the WCR.
Data Registers (DR3 to DR0)
The potentiometer has four 10-bit non-volatile Data
Registers. These can be read or written directly by the
host. Data can also be transferred between any of the
four Data Registers and the Wiper Counter Register.
All operations changing data in one of the Data
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, the Data Registers can
be used as regular memory locations for system
parameters or user preference data.
A DR[9:0] is used to store one of the 1024 wiper
position (0 ~1023). Table 2.
Status Register (SR)
This 1-bit status register is used to store the system
status (see Table 3).
WIP: Write In Progress status bit, read only.
– When WIP=1, indicates that high-voltage write cycle
is in progress.
– When WIP=0, indicates that no high-voltage write
cycle is in progress.
REV 1.1.15 5/9/03
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Characteristics subject to change without notice. 5 of 21