REV.0
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may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
a
AD5231
*
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
Nonvolatile Memory,
1024-Position Digital Potentiometers
FUNCTIONAL BLOCK DIAGRAM
RDAC
REGISTER
EEMEM1
DIGITAL
REGISTER
EEMEM
CONTROL
28 BYTES
USER EEMEM
EEMEM2
AD5231
RDAC
DIGITAL
OUTPUT
BUFFER
CS
CLK
WP
PR
SDI
GND
SDO
RDY
SDO
SERIAL
INTERFACE
ADDR
DECODE
V
DD
V
SS
A
W
B
O1
O2
SDI
2
CODE – Decimal
100
75
0
0 1023256
R
WA
(D),
R
WB
(D) – P
e
r
cent of Nominal – % R
AB
512 768
50
25
R
WB
R
WA
Figure 1. R
WA
(D) and R
WB
(D) vs. Decimal Code
FEATURES
Nonvolatile Memory
1
Preset Maintains Wiper Settings
1024-Position Resolution
Full Monotonic Operation
10 kH9024, 50 kH9024, and 100 kH9024 Terminal Resistance
Permanent Memory Write-Protection
Wiper Settings Read Back
Linear Increment/Decrement
Log Taper Increment/Decrement
Push Button Increment/Decrement Compatible
SPI Compatible Serial Interface with Readback Function
3 V to 5 V Single Supply or H115502.5 V Dual Supply
28 Bytes User Nonvolatile Memory for Constant Storage
100 Year Typical Data Retention T
A
= 55H11543C
APPLICATIONS
Mechanical Potentiometer Replacement
Instrumentation: Gain, Offset Adjustment
Programmable Voltage to Current Conversion
Programmable Filters, Delays, Time Constants
Line Impedance Matching
Power Supply Adjustment
Low Resolution DAC Replacement
GENERAL DESCRIPTION
The AD5231 provides nonvolatile memory digitally controlled
potentiometers
2
with 1024-position resolution. These devices
perform the same electronic adjustment function as a mechanical
potentiometer. The AD5231’s versatile programming via a stan-
dard 3-wire serial interface allows 16 modes of operation and
adjustment, including scratch pad programming, memory stor-
ing and retrieving, increment/decrement, log taper adjustment,
wiper setting read back, and extra user-defined EEMEM.
In the scratch pad programming mode, a specific setting can be
programmed directly to the RDAC
2
register, which sets the resis-
tance at terminals W-A and W-B. The RDAC register can also
be loaded with a value previously stored in the EEMEM
1
regis-
ter. The value in the EEMEM can be changed or protected.
When changes are made to the RDAC register, the value of the
new setting can be saved into the EEMEM. Thereafter, such value
will be transferred automatically to the RDAC register during
system power ON. It is enabled by the internal preset strobe.
EEMEM can also be retrieved through direct programming and
external preset pin control.
Other operations include linear step increment and decrement
commands such that the setting in the RDAC register can be
moved UP or DOWN, one step at a time. For logarithmic changes
in wiper setting, a left/right bit shift command adjusts the level
in ±6 dB steps.
The AD5231 is available in thin TSSOP-16 package. All parts
are guaranteed to operate over the extended industrial tempera-
ture range of –40°C to +85°C.
NOTES
1
The terms Nonvolatile Memory and EEMEM are used interchangeably.
2
The terms Digital Potentiometer and RDAC are used interchangeably.
*Patent pending