PRELIMINARY TECHNICAL DATA
a
FEATURES
Dual, 1024 Position Resolution
25K, 250K Ohm Terminal Resistance with 50ppm/擄C Tempco
Nonvolatile Memory Preset
SPI Compatible Serial Data Input with Readback Function
Increment/Decrement Commands, Push Button Command
+3 to +5V Single Supply Operation
鹵2.5V Dual Supply Operation
30 bytes of general purpose nonvolatile memory
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
Nonvolatile Memory, Dual 1024
Position Digital Potentiometers
AD5235
FUNCTIONAL BLOCK DIAGRAMS
RDAC1
CS
CLK
SDI
SDO
SER IAL
IN P U T
R E G IS T E R
ADDRESS
DECODE
V DD
A1
W1
B1
RDAC1
REGISTER
EEMEM1
RDAC2
PR
PWR ON
PRESET
RDAC2
REGISTER
A2
W2
B2
WP
RDY
EEMEM
CONTROL
EEMEM2
V SS
G ND
SPARE
EEMEM
G ND
GENERAL DESCRIPTION
The AD5235 provides a dual channel, digitally controlled variable
resistor (VR) with resolutions of 1024 positions. These devices
perform the same electronic adjustment function as a potentiometer or
variable resistor. The AD5235鈥檚 versatile programming via a Micro
Controller 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 micro controller. 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 establish 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 transferred automatically 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.
An internal scratch pad RDAC register can be programmed by the
micro controller to set the resistance between terminals W-and-B.
Once the target value is achieved, the RDAC content register can be
placed in the non-volatile memory for automatic recall during Power
Up.
The AD5235 is available in the thin TSSOP-16 package. All parts are
guaranteed to operate over the extended industrial temperature range
of -40擄C to +85擄C.
REV PrD 6 Nov 2000
Information furnished by Analog Devices is believed to be accurate and reliable. However, no
responsibility is assumed by Analog Devices for its use; nor for any infringements of patents or
other rights of third parties which may result from its use. No license is granted by implication
or otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106,
Norwood, MA 02062-9106 U
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S
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A
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Tel: 781/329-4700
Fax:781/326-8703
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