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Teilenummer | AD5262 |
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Beschreibung | 2-Channel/ 256-Position Digital Potentiometer | |
Hersteller | Analog Devices | |
Logo | ||
Gesamt 16 Seiten a
FEATURES
256-Position, 2-Channel
Potentiometer Replacement
10 k⍀, 50 k⍀, 100 k⍀
Power Shut-Down, Less than 5 A
2.7 V to 5.5 V Single Supply
؎2.7 V Dual Supply
3-Wire SPI-Compatible Serial Data Input
Midscale Preset During Power-On
APPLICATIONS
Mechanical Potentiometer Replacement
Stereo Channel Audio Level Control
Instrumentation: Gain, Offset Adjustment
Programmable Voltage-to-Current Conversion
Programmable Filters, Delays, Time Constants
Line Impedance Matching
Automotive Electronics Adjustment
2-Channel, 256-Position
Digital Potentiometer
AD5207
FUNCTIONAL BLOCK DIAGRAM
A1 W1 B1
A2 W2 B2
SHDN
VDD
VSS
CS
CLK
SDI
DGND
RDAC1 REGISTER
R
RDAC2 REGISTER
R
LOGIC
AD5207
POWER-
ON
RESET
8
SERIAL INPUT REGISTER
SDO
GENERAL DESCRIPTION
The AD5207 provides dual channel, 256-position, digitally
controlled variable resistor (VR) devices that perform the same
electronic adjustment function as a potentiometer or variable
resistor. Each channel of the AD5207 contains a fixed resistor with
a wiper contact that taps the fixed resistor value at a point
determined by a digital code loaded into the SPI-compatible
serial-input register. The resistance between the wiper and either
end point of the fixed resistor varies linearly with respect to the
digital code transferred into the VR latch. The variable resistor
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 10 kΩ, 50 kΩ or 100 kΩ
has a ± 1% channel-to-channel matching tolerance with a nomi-
nal temperature coefficient of 500 ppm/°C. A unique switching
circuit minimizes the high glitch inherent in traditional switched
resistor designs and avoids any make-before-break or break-
before-make operation.
Each VR has its own VR latch, which holds its programmed
resistance value. These VR latches are updated from an internal
serial-to-parallel shift register, which is loaded from a standard
3-wire serial-input digital interface. Ten bits, to make up the
data word, are required and clocked into the serial input register.
The first two bits are address bits. The following eight bits are
the data bits that represent the 256 steps of the resistance value.
The reason for two address bits instead of one is to be compatible
with similar products such as AD8402 so that drop-in replacement
is possible. The address bit determines the corresponding VR
latch to be loaded with the data bits during the returned positive
edge of CS strobe. A serial data output pin at the opposite end
of the serial register allows simple daisy chaining in multiple
VR applications without additional external decoding logic.
An internal reset block will force the wiper to the midscale posi-
tion during every power-up condition. The SHDN pin forces an
open circuit on the A Terminal and at the same time shorts the
wiper to the B Terminal, achieving a microwatt power shutdown
state. When SHDN is returned to logic high, the previous latch
settings put the wiper in the same resistance setting prior to
shutdown. The digital interface remains active during shutdown;
code changes can be made to produce new wiper positions when
the device is resumed from shutdown.
The AD5207 is available in 1.1 mm thin TSSOP-14 package,
which is suitable for PCMCIA applications. All parts are guaran-
teed to operate over the extended industrial temperature range
of –40°C to +125°C.
REV. 0
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 that
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., 2001
AD5207
45
VDD = 5.5V
40
35
30
25
20
15
10
5
0
–40 –20 0
20 40 60 80 100 120
TEMPERATURE – ؇C
TPC 7. Shutdown Current vs. Temperature
160
140
120
100
80 VDD = 3V
60
VDD = 5V
40
20
0
0 12345
VSUPPLY – V
TPC 8. Wiper ON Resistance vs. VSUPPLY
6
1000
900
CODE FFH
800
700
600
500 ISS @ VDD/VSS = ؎2.5V
400 IDD @ VDD/VSS = ؎2.5V
300
IDD @ VDD/VSS = 5V/0V
200
IDD @ VDD/VSS = 3V/0V
100
0
10k
100k
1M
FREQUENCY – Hz
10M
TPC 9. 10 kΩ Supply Current vs. Clock Frequency
1000
900
800
700
600
CODE 55H
ISS @ VDD/VSS = ؎2.5V
500 IDD @ VDD/VSS = ؎2.5V
400
300 IDD @ V DD/VSS = 5V/0V
200
IDD @ VDD/VSS = 3V/0V
100
0
10k
100k
1M
FREQUENCY – Hz
10M
TPC 10. 10 kΩ Supply Current vs. Clock Frequency
80
CODE = 80H, VA = VDD, VB = 0V
+PSRR @ VDD = 5V DC ؎10% p-p AC
60
40
+PSRR @ VDD = 3V DC ؎10% p-p AC
20
–PSRR @ VDD = 3V DC ؎10% p-p AC
0
100
1k 10k 100k
FREQUENCY – Hz
1M
TPC 11. Power Supply Rejection Ratio vs. Frequency
0
–6 DATA = 80H
DATA = 40H
–12
–18 DATA = 20H
–24 DATA = 10H
DATA = 08H
–30
DATA = 04H
–36
DATA = 02H
–42 DATA = 01H
–48 VDD = +2.7V
VA
VSS = –2.7V
–54 VA = 100mV rms
–60 TA = 25؇C
OP42
1k 10k 100k
FREQUENCY – Hz
1M
TPC 12. 10 kΩ Gain vs. Frequency vs. Code
–6– REV. 0
6 Page AD5207
TEST CIRCUITS
Figures 10 to 18 define the test conditions used in product
Specification table.
DUT
A
V+ = VDD
1 LSB = V+/2N
V+ W
B VMS
Figure 10. Potentiometer Divider Nonlinearity Error Test
Circuit (INL, DNL)
NO CONNECT
DUT
A
W
B
IW
VMS
Figure 11. Resistor Position Nonlinearity Error (Rheostat
Operation; R-INL, R-DNL)
VMS2
DUT
A
W
B
IW = VDD/RNOMINAL
VW
VMS1
RW = [VMS1 – V MS2]/IW
Figure 12. Wiper Resistance Test Circuit
VA
VDD A
V+ W V+ = VDD ؎10%
⌬VMS
B PSRR (dB) = 20 LOG ⌬VDD
VMS PSS (%/%) = ⌬VMS%
⌬VDD%
Figure 13. Power Supply Sensitivity Test Circuit
(PSS, PSSR)
A
VIN
OFFSET
GND
DUT B
W
5V
OP279
OFFSET BIAS
VOUT
Figure 14. Inverting Gain Test Circuit
5V
OP279
VIN
W
OFFSET
GND
A DUT B
OFFSET BIAS
VOUT
Figure 15. Noninverting Gain Test Circuit
OFFSET
GND
VIN
A
DUT
B
W
2.5V
+15V
OP42
–15V
VOUT
Figure 16. Gain vs. Frequency Test Circuit
DUT
W
B
RSW =
0.1V
ISW
CODE = ٠٠H
+
ISW 0.1V
–
VSS TO VDD
Figure 17. Incremental ON Resistance Test Circuit
NC
VDD
DUT
VSS GND
A
W
B
ICM
VCM
NC
NC = NO CONNECT
Figure 18. Common-Mode Leakage Current Test Circuit
–12–
REV. 0
12 Page | ||
Seiten | Gesamt 16 Seiten | |
PDF Download | [ AD5262 Schematic.PDF ] |
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