EVAL-AD5143DBZ Analog Devices, EVAL-AD5143DBZ Datasheet - Page 25

• Manufacturer Part Number: EVAL-AD5143DBZ
• Description: Digital Potentiometer Development Tools EVALUATION BOARD I.C.
• Manufacturer: Analog Devices
• Series: AD5143r

Specifications of EVAL-AD5143DBZ

• Rohs: yes
• Product: Evaluation Boards
• Tool Is For Evaluation Of: AD5143
• Resistance: 10 kOhms/100 kOhms
• Operating Supply Voltage: 5.5 V
• Interface Type: I2C
• Maximum Operating Temperature: + 125 C
• Factory Pack Quantity: 1

Data Sheet
RDAC ARCHITECTURE
To achieve optimum performance, Analog Devices, Inc., has
patented the RDAC segmentation architecture for all the digital
potentiometers. In particular, the
three-stage segmentation approach, as shown in Figure 36. The
AD5123/AD5143
gate CMOS topology and with the gate voltage derived from
V
Top Scale/Bottom Scale Architecture
In addition, the
reduce the resistance between terminals. These positions are
called bottom scale and top scale. At bottom scale, the typical
wiper resistance decreases from 130 Ω to 60 Ω (R
At top scale, the resistance between Terminal A and Terminal W is
decreased by 1 LSB, and the total resistance is reduced to 60 Ω
(R
PROGRAMMING THE VARIABLE RESISTOR
Rheostat Operation—±8% Resistor Tolerance
The
terminals are used as a variable resistor. The unused terminal can
be floating, or it can be tied to Terminal W, as shown in Figure 37.
DD
AB
7-BIT/8-BIT
ADDRESS
DECODER
and V
AD5123/AD5143
= 100 kΩ).
A
B
SS
Figure 36.
.
W
Figure 37. Rheostat Mode Configuration
AD5123/AD5143
wiper switch is designed with the transmission
AD5123/AD5143
A
B
operate in rheostat mode when only two
A
B
R
R
R
R
H
H
H
H
W
AD5123/AD5143
Simplified RDAC Circuit
include new positions to
R
R
R
R
M
M
M
M
A
B
S
S
R
R
TS
BS
L
L
AB
W
= 100 kΩ).
employ a
W
Rev. A | Page 25 of 28
The nominal resistance between Terminal A and Terminal B,
R
the wiper terminal. The 7-bit/8-bit data in the RDAC latch is
decoded to select one of the 128/256 possible wiper settings. The
general equations for determining the digitally programmed
output resistance between Terminal W and Terminal B are
AD5123:
AD5143:
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
R
R
In potentiometer mode, similar to the mechanical potentiometer,
the resistance between Terminal W and Terminal A also produces
a digitally controlled complementary resistance, R
gives a maximum of 8% absolute. R
resistance value and decreases as the data loaded into the latch
increases. The general equations for this operation are
AD5123:
AD5143:
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
R
R
If the part is configured in linear gain setting mode, the resistance
between Terminal W and Terminal A is directly proportional
to the code loaded in the associate RDAC register. The general
equations for this operation are
AD5123:
AD5143:
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
R
R
AB
AB
W
AB
W
AB
W
, is 10 kΩ or 100 kΩ, and has 128/256 tap points accessed by
is the wiper resistance.
is the wiper resistance.
is the wiper resistance.
is the end-to-end resistance.
is the end-to-end resistance.
is the end-to-end resistance.
R
R
R
R
R
R
WB
WB
AW
AW
AW
AW
(
(
(
(
(
(
D
D
D
D
D
D
)
)
)
)
)
)






128
256
128
256
128
D
256
D
D
D
128
256






R
R
D
D
R
R
AB
AB
AB

AB

R

R



AB
AB
R
R
R
W
R
W
W


W
R
R
W
W
WA
AD5123/AD5143
starts at the maximum
From 0x00 to 0x7F
From 0x00 to 0xFF
From 0x00 to 0x7F
From 0x00 to 0xFF (4)
From 0x00 to 0x7F (5)
From 0x00 to 0xFF (6)
WA
. R
WA
also
(1)
(2)
(3)