REV.0
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a
AD5232
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2001
*
8-Bit Dual Nonvolatile Memory
Digital Potentiometer
FEATURES
Nonvolatile Memory Preset Maintains Wiper Settings
Dual Channel, 256-Position Resolution
Full Monotonic Operation DNL < 1 LSB
10 kH9024, 50 kH9024, 100 kH9024 Terminal Resistance
Linear or Log Taper Settings
Push-Button Increment/Decrement Compatible
SPI-Compatible Serial Data Input with Readback
Function
3 V to 5 V Single Supply or H115502.5 V Dual Supply
Operation
14 Bytes of User EEMEM Nonvolatile Memory for
Constant Storage
Permanent Memory Write Protection
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
DIP Switch Setting
GENERAL DESCRIPTION
The AD5232 device provides a nonvolatile, dual-channel,
digitally controlled variable resistor (VR) with 256-position
resolution. These devices perform the same electronic adjust-
ment function as a potentiometer or variable resistor. The
AD5232’s versatile programming via a microcontroller allows
multiple modes of operation and adjustment.
In the direct program mode a predetermined setting of the RDAC
register can be loaded directly from the microcontroller.
Another key mode of operation allows the RDAC register to be
refreshed with the setting previously stored in the EEMEM
register. When changes are made to the RDAC register to estab-
lish a new wiper position, the value of the setting can be saved
into the EEMEM by executing an EEMEM save operation.
Once the settings are saved in the EEMEM register these values
will be automatically transferred to the RDAC register to set the
wiper position at system power ON. Such operation is enabled
by the internal preset strobe and the preset can also be accessed
externally.
All internal register contents can be read out of the serial data
output (SDO). This includes the RDAC1 and RDAC2 registers,
the corresponding nonvolatile EEMEM1 and EEMEM2 regis-
ters, and the 14 spare USER EEMEM registers available for
constant storage.
*Patent pending.
FUNCTIONAL BLOCK DIAGRAM
RDAC1
REGISTER
EEMEM1
RDAC2
REGISTER
EEMEM
CONTROL
14 BYTES
USER EEMEM
EEMEM2
AD5232
RDAC1
RDAC2
CS
CLK
WP
PR
SDI
GND
SDO
RDY
SDO
SERIAL
INTERFACE
ADDR
DECODE
V
DD
V
SS
A1
W1
B1
A2
W2
B2
SDI
The basic mode of adjustment is the increment and decrement
command controlling the present setting of the Wiper position
setting (RDAC) register. An internal scratch pad RDAC register
can be moved UP or DOWN one step of the nominal terminal
resistance between terminals A and B. This linearly changes the
wiper to B terminal resistance (R
WB
) by one position segment of
the devices’ end-to-end resistance (R
AB
). For exponential/loga-
rithmic changes in wiper setting, a left/right shift command
adjusts levels in ±6 dB steps, which can be useful for audio and
light alarm applications.
The AD5232 is available in a thin TSSOP-16 package. All parts
are guaranteed to operate over the extended industrial tempera-
ture range of –40°C to +85°C. An evaluation board is available,
Part Number: AD5232EVAL.
CODE – Decimal
100
75
0
0 25664
PERCENT OF NOMINAL
END-T
O
-END RESIST
ANCE – % R
AB
128 192
50
25
R
WB
R
WA
Figure 1. Symmetrical RDAC Operation