AD5222 Datasheet, PDF (1/10 Pages) Analog Devices – Increment/Decrement Dual Digital Potentiometer

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FEATURES
128-Position, 2-Channel
Potentiometer Replacement
10 k⍀, 50 k⍀, 100 k⍀, 1 M⍀
Very Low Power: 40 ␮A Max
؎2.7 V Dual Supply Operation or
2.7 V to 5.5 V Single Supply Operation
Increment/Decrement Count Control
APPLICATIONS
Stereo Channel Audio Level Control
Mechanical Potentiometer Replacement
Remote Incremental Adjustment Applications
Instrumentation: Gain, Offset Adjustment
Programmable Voltage-to-Current Conversion
Line Impedance Matching
Increment / Decrement
Dual Digital Potentiometer
AD5222
FUNCTIONAL BLOCK DIAGRAM
V_DD AD5222
A1
U/D
UP/DOWN
COUNTER
DECODE
W1
B1
POR
CS
DAC
A2
MODE
DACSEL
SELECT
AND
UP/DOWN
COUNTER
DECODE
W2
CLK
ENABLE
B2
GND
V_SS
GENERAL DESCRIPTION
The AD5222 provides a dual channel, 128-position, digitally
controlled variable-resistor (VR) device. This device performs
the same electronic adjustment function as a potentiometer or
variable resistor. These products were optimized for instrument
and test equipment push-button applications. Choices between
bandwidth or power dissipation are available as a result of the
wide selection of end-to-end terminal resistance values.
The AD5222 contains two fixed resistors with wiper contacts that
tap the fixed resistor value at a point determined by a digitally
controlled up/down counter. The resistance between the wiper
and either end point of the fixed resistor provides a constant
resistance step size that is equal to the end-to-end resistance
divided by the number of positions (e.g., R _STEP = 10 kΩ/128 =
78 Ω). The variable resistor offers a true adjustable value of
resistance, between Terminal A and the wiper, or Terminal B
and the wiper. The fixed A-to-B terminal resistance of 10 kΩ,
50 kΩ, 100 kΩ, or 1 MΩ has a nominal temperature coefficient
of –35 ppm/°C.
The chip select CS, count CLK and U/D direction control inputs
set the variable resistor position. The MODE determines whether
both VRs are incremented together or independently. With
MODE at logic zero, both wipers are incremented UP or DOWN
without changing the relative settings between the wipers. Also,
the relative ratio between the wipers is preserved if either wiper
reaches the end of the resistor array. In the independent MODE
(Logic 1) only the VR determined by the DACSEL pin is changed.
DACSEL (Logic 0) changes RDAC 1. These inputs, which con-
trol the internal up/down counter, can be easily generated with
mechanical or push-button switches (or other contact closure
devices). This simple digital interface eliminates the need for
microcontrollers in front panel interface designs.
The AD5222 is available in the surface-mount (SO-14) package.
For ultracompact solutions, selected models are available in the
thin TSSOP-14 package. All parts are guaranteed to operate
over the extended industrial temperature range of –40°C to
+85°C. For 3-wire, SPI-compatible interface applications, see
the AD5203/AD5204/AD5206, AD7376, and AD8400/AD8402/
AD8403 products.
5V
V_DD
CS
A1
U/D
U/D
W1
CLK
B1
INCREMENT
A2
DACSEL
W2
MODE
B2
GND
V_SS
Figure 1. Typical Push-Button Control Application
REV. 0
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