Datenblatt-pdf.com


AD5280 Schematic ( PDF Datasheet ) - Analog Devices

Teilenummer AD5280
Beschreibung +15V/ I2C Compatible Digital Potentiometers
Hersteller Analog Devices
Logo Analog Devices Logo 




Gesamt 10 Seiten
AD5280 Datasheet, Funktion
PRELIMINARY TECHNICAL DATA
a
+15V, I2C Compatible
Digital Potentiometers
Preliminary Technical Data
AD5280/AD5282
FEATURES
256 Position
AD5280 – 1-Channel
AD5282 – 2-Channel (Independently Programmable)
Potentiometer Replacement
20K, 50K, 200K Ohm with TC < 50ppm/ºC
Internal Power ON Mid-Scale Preset
+5 to +15V Single-Supply; ±5.5V Dual-Supply Operation
I2C Compatible Interface
APPLICATIONS
Multi-Media, Video & Audio
Communications
Mechanical Potentiometer Replacement
Instrumentation: Gain, Offset Adjustment
Programmable Voltage to Current Conversion
Line Impedance Matching
GENERAL DESCRIPTION
The AD5280/AD5282 provides a single/dual channel, 256 position
digitally-controlled variable resistor (VR) device. These devices
perform the same electronic adjustment function as a
potentiometer, trimmer or variable resistor. Each VR offers a
completely programmable value of resistance, between the A
terminal and the wiper, or the B terminal and the wiper. The fixed
A-to-B terminal resistance of 20, 50 or 200K ohms has a 1%
channel-to-channel matching tolerance with a nominal temperature
coefficient of 30 ppm/°C.
Wiper Position programming defaults to midscale at system power
ON. Once powered the VR wiper position is programmed by a I2C
compatible 2-wire serial data interface. Both parts have two
programmable logic outputs available to drive digital loads, gates,
LED drivers, analog switches, etc.
FUNCTIONAL BLOCK DIAGRAMS
A1 W1 B1
O1 O2
SHDN
VDD
VSS
VL
SCL
SDA
GND
RDAC1 REGISTER
R
RDAC2 REGISTER
R
ADDRESS
DECODE
AD5280
PWR ON
RESET
8
SERIAL INPUT REGISTER
AD0 AD1
A1 W1 B1
A2 W2 B2
O1
SHDN
VDD
VSS
VL
SCL
SDA
GND
RDAC1 REGISTER
R
RDAC2 REGISTER
R
ADDRESS
DECODE
AD5282
PWR ON
RESET
8
SERIAL INPUT REGISTER
OUTPUT
REGISTER
R
AD0 AD1
The AD5280/AD5282 are available in ultra compact surface mount
thin TSSOP-14/-16 packages. 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
AD5203/AD5204/AD5206/AD7376/AD8400/AD8402/AD8403/
AD5260/AD5262/AD5200/AD5201 products.
Model
AD5280BRU20
AD5280BRU50
AD5280BRU200
ORDERING GUIDE
Kilo
Ohms Temp
Package
Description
20 -40/+85°C TSSOP-14
50 -40/+85°C TSSOP-14
200 -40/+85°C TSSOP-14
Package
Option
RU-14
RU-14
RU-14
AD5282BRU20
AD5282BRU50
AD5282BRU200
20
50
200
-40/+85°C
-40/+85°C
-40/+85°C
TSSOP-16
TSSOP-16
TSSOP-16
RU-16
RU-16
RU-16
The AD5280/AD5282 die size is 75 mil X 120 mil, 9,000 sq. mil.
Contains xxx transistors. Patent Number xxx applies.
REV PrE 12 MAR 02
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.S.A.
Tel: 781/329-4700
www.analog.com
Fax: 781/326-8703
©Analog Devices, Inc., 2002






AD5280 Datasheet, Funktion
PRELIMINARY TECHNICAL DATA
AD5280/AD5282
SCL
1
91
SDA
START BY
M AS TE R
0 1 0 1 1 AD1 AD0 R/ W
D7 D6 D5
FRAME 1
Slave Address Byte
ACK. BY
AD5280
Figure 3. Reading Data from a Previously Selected RDAC Register
D4 D3 D2 D1
FRAME 2
Data From Select ed
RDAC Regis ter
9
D0
NO ACK.
BY MASTER
STO P BY
M A STE R
OPERATION
The AD5280/AD5282 provides a single/dual channel, 256-
position digitally-controlled variable resistor (VR) device. The
terms VR and RDAC are used interchangeably throughout this
documentation. To program the VR settings, refer to the Digital
Interface section. Both parts have an internal power ON preset
that places the wiper in mid scale during power on, which
simplifies the fault condition recovery at power up. In addition,
the shutdown SHDN pin of AD5280/AD5282 places the RDAC
in a zero power consumption state where terminal A is open
circuited and the wiper W is connected to terminal B, resulting
in only leakage currents being consumed in the VR structure. In
shutdown mode the VR latch settings are maintained, so that,
returning to operational mode from power shutdown, the VR
settings return to their previous resistance values.
SHDN
D7
D6
D5
D4
D3
D2
D1
D0
RS
RS
RS
Ax
Wx
for data 02H and so on. Each LSB data value increase moves the
wiper up the resistor ladder until the last tap point is reached at
19982[RAB–1LSB+RW]. The wiper does not directly connect
to the B terminal. See Figure 4 for a simplified diagram of the
equivalent RDAC circuit.
The general equation determining the digitally programmed
output resistance between W and B is:
RWB (D)
=
D
256
R AB
+RW
eqn.1
where D is the decimal equivalent of the binary code which is
loaded in the 8-bit RDAC register, and RAB is the nominal end-
to-end resistance.
For example, RAB=20K, when VB = 0V and A–terminal is open
circuit, the following output resistance values RWB will be set for
the following RDAC latch codes. Result will be the same if
terminal A is tied to W:
D RWB
(DEC) (Ω)
Output State
RDAC
LATCH
&
DECODER RS
Bx
256 19982Full-Scale (RAB - 1LSB + RW)
128 10060Mid-Scale
1 1381 LSB
0 60Zero-Scale (Wiper contact resistance)
Figure 4. AD5280/AD5282 Equivalent RDAC Circuit
PROGRAMMING THE VARIABLE RESISTOR
Rheostat Operation
Note that in the zero-scale condition a finite wiper resistance of
60is present. Care should be taken to limit the current flow
between W and B in this state to a maximum current of no more
than 5mA. Otherwise, degradation or possible destruction of the
internal switch contact can occur.
The nominal resistance of the RDAC between terminals A and B
are available in 20K, 50K, and 200K. The final three
digits of the part number determine the nominal resistance
value, e.g. 20K= 20; 50K= 50; 200K= 200. The
nominal resistance (RAB) of the VR has 256 contact points
accessed by the wiper terminal, plus the B terminal contact. The
eight bit data in the RDAC latch is decoded to select one of the
256 possible settings. Assume a 20Kpart is used, the wiper's
first connection starts at the B terminal for data 00H. Since there
is a 60wiper contact resistance, such connection yields a
minimum of 60resistance between terminals W and B. The
second connection is the first tap point corresponds to 138
(RWB = RAB/256 + RW = 78+60) for data 01H. The third
connection is the next tap point representing 216(78x2+60)
Similar to the mechanical potentiometer, the resistance of the
RDAC between the wiper W and terminal A also produces a
digitally controlled resistance RWA. When these terminals are
used the B–terminal should be let open or tied to the wiper
terminal. Setting the resistance value for RWA starts at a
maximum value of resistance and decreases as the data loaded in
the latch is increased in value. The general equation for this
operation is:
RWA (D)
=
256 D
256
R AB
+
RW
eqn. 2
6 REV PrE 12 MAR 02
Information contained in this Product Concept Data Sheet describes a product in the early definition stage. There is no guarantee that the information contained here will become a final
product in its present form. For latest information contact Walt Heinzer/Analog Devices, Santa Clara, CA. TEL 408 382-3107; FAX 408 382-2721; email; [email protected]

6 Page







SeitenGesamt 10 Seiten
PDF Download[ AD5280 Schematic.PDF ]

Link teilen




Besondere Datenblatt

TeilenummerBeschreibungHersteller
AD5280+15V/ I2C Compatible Digital PotentiometersAnalog Devices
Analog Devices
AD5282+15V/ I2C Compatible Digital PotentiometersAnalog Devices
Analog Devices

TeilenummerBeschreibungHersteller
CD40175BC

Hex D-Type Flip-Flop / Quad D-Type Flip-Flop.

Fairchild Semiconductor
Fairchild Semiconductor
KTD1146

EPITAXIAL PLANAR NPN TRANSISTOR.

KEC
KEC


www.Datenblatt-PDF.com       |      2020       |      Kontakt     |      Suche