Electronic Components Datasheet Search
  English  ▼

Delete All
ON OFF
ALLDATASHEET.COM

X  

Preview PDF Download HTML

AD5122 Datasheet(PDF) 27 Page - Analog Devices

Part No. AD5122
Description  Dual Channel, 128-/256-Position, SPI, Nonvolatile Digital Potentiometer
Download  32 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  AD [Analog Devices]
Direct Link  http://www.analog.com
Logo AD - Analog Devices

AD5122 Datasheet(HTML) 27 Page - Analog Devices

Back Button AD5122_17 Datasheet HTML 23Page - Analog Devices AD5122_17 Datasheet HTML 24Page - Analog Devices AD5122_17 Datasheet HTML 25Page - Analog Devices AD5122_17 Datasheet HTML 26Page - Analog Devices AD5122_17 Datasheet HTML 27Page - Analog Devices AD5122_17 Datasheet HTML 28Page - Analog Devices AD5122_17 Datasheet HTML 29Page - Analog Devices AD5122_17 Datasheet HTML 30Page - Analog Devices AD5122_17 Datasheet HTML 31Page - Analog Devices Next Button
Zoom Inzoom in Zoom Outzoom out
 27 / 32 page
background image
Data Sheet
AD5122/AD5142
Rev. C | Page 27 of 32
RDAC ARCHITECTURE
To achieve optimum performance, Analog Devices, Inc., uses a
proprietary RDAC segmentation architecture for all the digital
potentiometers. In particular, the AD5122/AD5142 employ a
three stage segmentation approach, as shown in Figure 42. The
AD5122/AD5142 wiper switch is designed with the transmission
gate CMOS topology and with the gate voltage derived from
VDD and VSS.
7-BIT/8-BIT
ADDRESS
DECODER
RL
W
RL
A
RH
RH
RM
RM
B
RM
RM
RH
RH
STS
SBS
Figure 42. AD5122/AD5142 Simplified RDAC Circuit
Top Scale/Bottom Scale Architecture
In addition, the AD5122/AD5142 include new positions to
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 (RAB = 100 kΩ).
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
(RAB = 100 kΩ).
PROGRAMMING THE VARIABLE RESISTOR
Rheostat Operation—±8% Resistor Tolerance
The AD5122/AD5142 operate in rheostat mode when only two
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 43.
A
W
B
A
W
B
A
W
B
Figure 43. Rheostat Mode Configuration
The nominal resistance between Terminal A and Terminal B, RAB,
is 10 kΩ or 100 kΩ, and has 128/256 tap points accessed by 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
AD5122:
W
AB
WB
R
R
D
D
R
128
)
(
From 0x00 to 0x7F
(1)
AD5142:
W
AB
WB
R
R
D
D
R
256
)
(
From 0x00 to 0xFF
(2)
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
RAB is the end-to-end resistance.
RW is the wiper resistance.
In potentiometer mode, similar to the mechanical potentiometer,
the resistance between Terminal W and Terminal A also produces
a digitally controlled complementary resistance, RWA. RWA also
gives a maximum of 8% absolute resistance error. RWA starts at the
maximum resistance value and decreases as the data loaded into
the latch increases. The general equations for this operation are
AD5122:
W
AB
AW
R
R
D
D
R
128
128
)
(
From 0x00 to 0x7F
(3)
AD5142:
W
AB
AW
R
R
D
D
R
256
256
)
(
From 0x00 to 0xFF (4)
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
RAB is the end-to-end resistance.
RW is the wiper resistance.
If the device 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
AD5122:
W
AB
AW
R
R
D
D
R
128
)
(
From 0x00 to 0x7F (5)
AD5142:
W
AB
AW
R
R
D
D
R
256
)
(
From 0x00 to 0xFF (6)
where:
D is the decimal equivalent of the binary code in the 7-bit/8-bit
RDAC register.
RAB is the end-to-end resistance.
RW is the wiper resistance.


Html Pages

1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31  32 


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   Link Exchange   |   Manufacturer List
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn