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參數(shù)資料
| 型號(hào)： | ADR293FR |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Low Noise Micropower Precision Voltage Reference |
| 中文描述： | 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 5 V, PDSO8 |
| 封裝： | MS-012AA, SOIC-8 |
| 文件頁(yè)數(shù)： | 9/11頁(yè) |
| 文件大?。?/td> | 159K |
| 代理商： | ADR293FR |
ADR293
REV. 0
–9–
APPLICATIONS
A Negative Precision Reference without Precision Resistors
In many current-output CMOS DAC applications where the
output signal voltage must be of the same polarity as the refer-
ence voltage, it is often required to reconfigure a current-
switching DAC into a voltage-switching DAC through the use
of a 1.25 V reference, an op amp and a pair of resistors. Using
a current-switching DAC directly requires the need for an
additional operational amplifier at the output to reinvert the
signal. A negative voltage reference is then desirable from the
point that an additional operational amplifier is not required
for either reinversion (current-switching mode) or amplifica-
tion (voltage-switching mode) of the DAC output voltage. In
general, any positive voltage reference can be converted into a
negative voltage reference through the use of an operational
amplifier and a pair of matched resistors in an inverting configu-
ration. The disadvantage to that approach is that the largest single
source of error in the circuit is the relative matching of the resis-
tors used.
The circuit illustrated in Figure 20 avoids the need for tightly
matched resistors with the use of an active integrator circuit.
In this circuit, the output of the voltage reference provides the
input drive for the integrator. The integrator, to maintain circuit
equilibrium, adjusts its output to establish the proper relation-
ship between the reference’s V
OUT
and GND. One caveat with
this approach should be mentioned: although rail-to-rail output
amplifiers work best in the application, these operational ampli-
fiers require a finite amount (mV) of headroom when required
to provide any load current. The choice for the circuit’s negative
supply should take this issue into account.
ADR293
1
m
F
4
6
2
V
IN
GND
V
OUT
100k
V
1
m
F
–V
REF
A
1
–5V
+5V
100
V
1k
V
A
1
= 1/2 OP291,
1/2 OP295
Figure 20. A Negative Precision Voltage Reference Uses
No Precision Resistors
A Precision Current Source
Many times in low power applications, the need arises for a preci-
sion current source that can operate on low supply voltages. As
shown in Figure 21, the ADR293 is configured as a precision
current source. The circuit configuration illustrated is a floating
current source with a grounded load. The reference’s output
voltage is bootstrapped across R
SET
, which sets the output current
into the load. With this configuration, circuit precision is main-
tained for load currents in the range from the reference’s supply
current, typically 15
μ
A to approximately 5 mA.
ADR293
4
6
2
V
IN
GND
V
OUT
R
L
1
m
F
I
OUT
6
P
1
R
1
R
SET
I
SY
ADJUST
Figure 21. A Precision Current Source
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| ADR293FR-REEL | 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Noise Micropower Precision Voltage Reference |
| ADR293FR-REEL7 | 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Noise Micropower Precision Voltage Reference |
| ADR293FRZ | 制造商:Analog Devices 功能描述:V-Ref Precision 5V 5mA 8-Pin SOIC N Tube 制造商:Rochester Electronics LLC 功能描述:LOW NOISE, MICROPWR PRECISION VOLT. REF. - Bulk |
| ADR293GBC | 制造商:AD 制造商全稱:Analog Devices 功能描述:Low Noise Micropower Precision Voltage Reference |
| ADR293GR | 制造商:Analog Devices 功能描述:V-Ref Precision 5V 5mA 8-Pin SOIC N Tube 制造商:Rochester Electronics LLC 功能描述:LOW NOISE, MICROPWR PRECISION VOLT. REF. - Bulk 制造商:Analog Devices 功能描述:IC VOLT REF |
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