AD5547 Просмотр технического описания (PDF) - Analog Devices
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AD5547 Datasheet PDF : 20 Pages
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AD5547/AD5557
Data Sheet
REFERENCE SELECTION
When selecting a reference for use with the AD55xx series of
current output DACs, pay attention to the output voltage,
temperature coefficient specification of the reference. Choosing
a precision reference with a low output temperature coefficient
minimizes error sources. Table 10 lists some of the references
available from Analog Devices, Inc., that are suitable for use
with this range of current output DACs.
AMPLIFIER SELECTION
The primary requirement for the current-steering mode is an
amplifier with low input bias currents and low input offset voltage.
Because of the code-dependent output resistance of the DAC,
the input offset voltage of an op amp is multiplied by the variable
gain of the circuit. A change in this noise gain between two
adjacent digital fractions produces a step change in the output
voltage due to the amplifier’s input offset voltage. This output
voltage change is superimposed upon the desired change in output
between the two codes and gives rise to a differential linearity error,
which, if large enough, can cause the DAC to be nonmonotonic.
The input bias current of an op amp also generates an offset at
the voltage output because of the bias current flowing in the
feedback resistor, RFB.
Common-mode rejection of the op amp is important in voltage-
switching circuits because it produces a code-dependent error
at the voltage output of the circuit.
Provided that the DAC switches are driven from true wideband
low impedance sources (VIN and AGND), they settle quickly.
Consequently, the slew rate and settling time of a voltage-switching
DAC circuit is determined largely by the output op amp. To obtain
minimum settling time in this configuration, minimize capacitance
at the VREF node (the voltage output node in this application) of
the DAC. This is done by using low input capacitance buffer
amplifiers and careful board design.
Analog Devices offers a wide range of amplifiers for both precision
dc and ac applications, as listed in Table 11 and Table 12.
Table 10. Suitable Analog Devices Precision References
Maximum Temperature
Part No. Output Voltage (V) Initial Tolerance (%) Drift (ppm/°C)
ADR01 10
0.05
3
ADR01 10
0.05
9
ADR02 5.0
0.06
3
ADR02 5.0
0.06
9
ADR03 2.5
0.1
3
ADR03 2.5
0.1
9
ADR06 3.0
0.1
3
ADR06 3.0
0.1
9
ADR420 2.048
0.05
3
ADR421 2.50
0.04
3
ADR423 3.00
0.04
3
ADR425 5.00
0.04
3
ADR431 2.500
0.04
3
ADR435 5.000
0.04
3
ADR391 2.5
0.16
9
ADR395 5.0
0.10
9
ISS (mA)
1
1
1
1
1
1
1
1
0.5
0.5
0.5
0.5
0.8
0.8
0.12
0.12
Output Noise (µV p-p)
20
20
10
10
6
6
10
10
1.75
1.75
2
3.4
3.5
8
5
8
Package(s)
SOIC-8
TSOT-5, SC70-5
SOIC-8
TSOT-5, SC70-5
SOIC-8
TSOT-5, SC70-5
SOIC-8
TSOT-5, SC70-5
SOIC-8, MSOP-8
SOIC-8, MSOP-8
SOIC-8, MSOP-8
SOIC-8, MSOP-8
SOIC-8, MSOP-8
SOIC-8, MSOP-8
TSOT-5
TSOT-5
Table 11. Suitable Analog Devices Precision Op Amps
Part No.
VOS Maximum IB Maximum
Supply Voltage (V) (µV)
(nA)
OP97
±2 to ±20
25
0.1
OP1177
±2.5 to ±15
60
2
AD8675
±5 to ±18
75
2
AD8671
±5 to ±15
75
12
ADA4004-1 ±5 to ±15
125
90
AD8603
1.8 to 5
50
0.001
AD8607
1.8 to 5
50
0.001
AD8605
2.7 to 5
65
0.001
AD8615
2.7 to 5
65
0.001
AD8616
2.7 to 5
65
0.001
0.1 Hz to 10 Hz
Noise (µV p-p)
0.5
0.4
0.1
0.077
0.1
2.3
2.3
2.3
2.4
2.4
Supply Current (µA)
600
500
2300
3000
2000
40
40
1000
2000
2000
Package(s)
SOIC-8 , PDIP-8
MSOP-8, SOIC-8
MSOP-8, SOIC-8
MSOP-8, SOIC-8
SOIC-8, SOT-23-5
TSOT-5
MSOP-8, SOIC-8
WLCSP-5, SOT-23-5
TSOT-5
MSOP-8, SOIC-8
Rev. D | Page 18 of 20
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