X9111 Datasheet, PDF (7/21 Pages) Xicor Inc. – Single Digitally-Controlled Potentiometer

X9111 – Preliminary Information
Five of the seven instructions are four bytes in length.
These instructions are:
– Read Wiper Counter Register – read the current
wiper position of the selected pot,
– Write Wiper Counter Register – change current
wiper position of the selected pot,
– Read Data Register – read the contents of the
selected data register;
– Write Data Register – write a new value to the
selected data register.
– Read Status – This command returns the contents
of the WIP bit which indicates if the internal write
cycle is in progress.
The basic sequence of the four byte instructions is
illustrated in Figure 3. These four-byte instructions
exchange data between the WCR and one of the Data
Registers. A transfer from a Data Register to a WCR is
essentially a write to a static RAM, with the static RAM
controlling the wiper position. The response of the
wiper to this action will be delayed by t_WRL. A transfer
from the WCR (current wiper position), to a Data
Register is a write to nonvolatile memory and takes a
minimum of t_WR to complete. The transfer can occur
between the potentiometer and one of its associated
registers. The Read Status Register instruction is the
only unique format (see Figure 4).
Two instructions require a two-byte sequence to
complete (see Figure 2). These instructions transfer
data between the host and the X9111; either between
the host and one of the Data Registers or directly
between the host and the Wiper Counter Register.
These instructions are:
– XFR Data Register to Wiper Counter Register –
This transfers the contents of one specified Data
Register to the associated Wiper Counter Register.
– XFR Wiper Counter Register to Data Register –
This transfers the contents of the specified Wiper
Counter Register to the specified associated Data
Register.
See Instruction format for more details.
Write in Process (WIP bit)
The contents of the Data Registers are saved to
nonvolatile 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 operation
can be monitored by a Write In Process bit (WIP). The
WIP bit is read with a Read Status command (see
Figure 4).
Power Up and Down Requirements
There are no restrictions on the power-up condition of
V_CC and the voltages applied to the potentiometer pins
provided that the V_CC is always more positive than or
equal to the voltages at R_H, R_L, and R_W, i.e., V_CC ≥
R_H, R_L, R_W. There are no restrictions on the power-
down condition. However, the datasheet parameters
for the DCP do not apply until 1millisecond after V_CC
reaches its final value.
Figure 2. Two-Byte Instruction Sequence
CS
SCK
SI
0 1 0 10
0
00
ID3 ID2 ID1 ID0 0 A1 A0 R/W I2 I1 I0
RB RA 0 0
Device ID
Internal
Address
Instruction
Opcode
Register
Address
REV 1.1.15 5/9/03
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