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參數資料
| 型號： | ADR380 |
| 廠商： | Analog Devices, Inc. |
| 英文描述： | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| 中文描述： | 精密低漂移2.048 V/2.500 V SOT - 23封裝電壓基準 |
| 文件頁數： | 11/12頁 |
| 文件大小： | 316K |
| 代理商： | ADR380 |
REV. A
ADR380/ADR381
–11–
reference is then desirable from the point that an additional
operational amplifier is not required for either reinversion
(current-switching mode) or amplification (voltage-switching
mode) of the DAC output voltage. In general, any positive
voltage reference can be converted into a negative voltage refer-
ence through the use of an operational amplifier and a pair of
matched resistors in an inverting configuration. The disadvan-
tage to this approach is that the largest single source of error in
the circuit is the relative matching of the resistors used.
The circuit in Figure 3 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 relationship between
the reference’s V
OUT
and GND. Thus, any negative output
voltage desired can be chosen by simply substituting for the
appropriate reference IC. A precaution should be noted with
this approach: although rail-to-rail output amplifiers work best
in the application, these operational amplifiers 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.
GND
3
V
OUT
U1
ADR380
V
IN
C2
0.1 F
+5V
–V
REF
V
IN
R4
1k
C1
1 F
C3
1 F
2
R3
100k
A1
1
C4
1 F
U2
–5V
OP195
R5
100
–V
+V
Figure 3. A Negative Precision Voltage Reference
Uses No Precision Resistors
Precision Current Source
Many times in low power applications, the need arises for a pre-
cision current source that can operate on low supply voltages.
As shown in Figure 4, the ADR380/ADR381 can be 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
(R1 + P1), which sets
the output current into the load. With this configuration, circuit
precision is maintained for load currents in the range from the
reference’s supply current, typically 90
μ
A to approximately 5 mA.
GND
V
OUT
V
IN
U1
ADR380
C2
0.1 F
3
V
IN
C1
1 F
C3
1 F
2
R1
1
R
L
P1
I
OUT
I
SY
ADJUST
Figure 4. A Precision Current Source
Precision High Current Voltage Source
In some cases, the user may want higher output current delivered
to a load and still achieve better than 0.5% accuracy out of the
ADR380/ADR381. The accuracy for a reference is normally
specified on the data sheet with no load. However, the output
voltage changes with load current.
The circuit in Figure 5 provides high current without compro-
mising the accuracy of the ADR380/ADR381. By op amp action,
V
O
follows V
REF
with very low drop in R1. To maintain circuit
equilibrium, the op amp also drives the N-Ch MOSFET Q1 into
saturation to maintain the current needed at different loads. R2
is optional to prevent oscillation at Q1. In such an approach, hun-
dreds of milliamps of load current can be achieved and the current
is limited by the thermal limitation of Q1. V
IN
= V
O
+ 300 mV.
GND
3
V
OUT
U1
ADR380/
ADR381
V
IN
V
O
2
R2
100
1
C1
0.001 F
Q1
2N7002
+8 –15V
R1
100k
R
L
V
IN
A1
–V
+V
AD820
Figure 5. ADR380/ADR381 for Precision High
Current Voltage Source
相關PDF資料 |
PDF描述 |
|---|---|
| ADR380ART-R2 | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| ADR380ARTZ-REEL7 | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| ADR381ART-R2 | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| ADR381ARTZ-REEL7 | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| ADR380ART-REEL | Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
相關代理商/技術參數 |
參數描述 |
|---|---|
| ADR380ART | 制造商:Analog Devices 功能描述:Voltage Reference, Fixed, 2.048V, 3 Pin, Plastic, TO-236 |
| ADR380ART-R2 | 制造商:Analog Devices 功能描述:V-Ref Precision 2.048V 5mA 3-Pin SOT-23 T/R 制造商:Rochester Electronics LLC 功能描述:2.048 VOLTAGE REFERENCE - Bulk 制造商:Analog Devices 功能描述:IC VOLT REF |
| ADR380ART-REEL | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Low-Drift 2.048 V/2.500 V SOT-23 Voltage References |
| ADR380ART-REEL7 | 制造商:Analog Devices 功能描述:V-Ref Precision 2.048V 5mA 3-Pin SOT-23 T/R |
| ADR380ARTZ | 制造商:Analog Devices 功能描述:VREF PREC LP 2.048V SOT-23 制造商:Analog Devices 功能描述:VREF, PREC, LP, 2.048V, SOT-23 制造商:Analog Devices 功能描述:VREF, PREC, LP, 2.048V, SOT-23; Input Voltage Max:12V; Reference Voltage:2.048V; Reference Voltage Tolerance:5mV; Voltage Reference Case Style:SOT-23; No. of Pins:3; Temperature Coefficient:25ppm/C; MSL:MSL 1 - Unlimited; SVHC:No ;RoHS Compliant: Yes 制造商:Analog Devices 功能描述:ADR380ARTZ |
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