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參數資料
| 型號： | ADR293GBC |
| 廠商： | ANALOG DEVICES INC |
| 元件分類： | 基準電壓源/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, UUC4 |
| 文件頁數： | 8/11頁 |
| 文件大小： | 159K |
| 代理商： | ADR293GBC |
ADR293
REV. 0
–8–
Device Power Dissipation Considerations
The ADR293 is guaranteed to deliver load currents to 5 mA
with an input voltage that ranges from 5.5 V to 15 V. When this
device is used in applications with large input voltages, care
should be exercised to avoid exceeding the published specifica-
tions for maximum power dissipation or junction temperature
that could result in premature device failure. The following
formula should be used to calculate a device’s maximum junc-
tion temperature or dissipation:
P
T
T
D
A
A
=
J
J
θ
In this equation,
T
J
and
T
A
are the junction and ambient tem-
peratures, respectively, P
D
is the device power dissipation, and
θ
J
A
is the device package thermal resistance.
Basic Voltage Reference Connections
References, in general, require a bypass capacitor connected
from the V
OUT
pin to the GND pin. The circuit in Figure 19
illustrates the basic configuration for the ADR293. Note that
the decoupling capacitors are not required for circuit stability.
ADR293
1
2
3
4
8
7
6
5
NC
NC
NC
NC
NC
OUTPUT
0.1
m
F
10
m
F
0.1
m
F
+
INPUT
NC = NO CONNECT
Figure 19. Basic Voltage Reference Configuration
Noise Performance
The noise generated by the ADR293 is typically less than
15
μ
Vp-p over the 0.1 Hz to 10 Hz band. The noise measure-
ment is made with a bandpass filter made of a 2-pole high-pass
filter with a corner frequency at 0.1 Hz and a 2-pole low-pass
filter with a corner frequency at 10 Hz.
Turn-On Time
Upon application of power (cold start), the time required for the
output voltage to reach its final value within a specified error
band is defined as the turn-on settling time. Two components
normally associated with this are; the time for the active circuits
to settle, and the time for the thermal gradients on the chip to
stabilize. Figure 13 shows the typical turn-on time for the
ADR293.
THEORY OF OPERATION
The ADR293 uses a new reference generation technique known
as XFET,
which yields a reference with low noise, low supply
current and very low thermal hysteresis.
The core of the XFET reference consists of two junction field-
effect transistors one of which has an extra channel implant to
raise its pinch-off voltage. By running the two JFETS at the
same drain current, the difference in pinch-off voltage can be
amplified and used to form a highly stable voltage reference.
The intrinsic reference voltage is around 0.5 V with a negative
temperature coefficient of about –120 ppm/K. This slope is
essentially locked to the dielectric constant of silicon and can be
closely compensated by adding a correction term generated in
the same fashion as the proportional-to-temperature (PTAT)
term used to compensate bandgap references. The big advan-
tage over a bandgap reference is that the intrinsic temperature
coefficient is some thirty times lower (therefore less correction is
needed) and this results in much lower noise since most of the
noise of a bandgap reference comes from the temperature com-
pensation circuitry.
The simplified schematic below shows the basic topology of the
ADR293. The temperature correction term is provided by a
current source with value designed to be proportional to abso-
lute temperature. The general equation is:
V
V
R
R
R
R
I
R
OUT
P
PTAT
=
+
+
+
(
)(
)
1
2
1
3
3
where
V
P
is the difference in pinch-off voltage between the two
FETs and
I
PTAT
is the positive temperature coefficient correction
current.
The process used for the XFET reference also features vertical
NPN and PNP transistors, the latter of which are used as output
devices to provide a very low drop-out voltage.
R1
R3
R2
R1
R3
I
1
I
1
I
PTAT
V
OUT
R1
R2
R3
D
V
P
*
EXTRA CHANNEL IMPLANT
1
*
V
OUT
5
1
3D
V
P
1
I
PTAT
3
GND
V
IN
Figure 18. Simplified Schematic
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相關代理商/技術參數 |
參數描述 |
|---|---|
| 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 |
| ADR293GR-REEL | 制造商:Rochester Electronics LLC 功能描述:- Tape and Reel |
| ADR293GR-REEL7 | 制造商:Analog Devices 功能描述:V-Ref Precision 5V 5mA 8-Pin SOIC N T/R 制造商:Rochester Electronics LLC 功能描述:LOW NOISE, MICROPWR PRECISION VOLT. REF. - Tape and Reel |
| ADR293GRU | 制造商:Analog Devices 功能描述:V-Ref Precision 5V 5mA 8-Pin TSSOP Tube 制造商:Rochester Electronics LLC 功能描述:LOW NOISE, MICROPWR PRECISION VOLT. REF. - Bulk |
| ADR293GRU-REEL | 制造商:Analog Devices 功能描述:V-Ref Precision 5V 5mA 8-Pin TSSOP T/R 制造商:Rochester Electronics LLC 功能描述:LOW NOISE, MICROPWR PRECISION VOLT. REF. - Tape and Reel |
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