參數(shù)資料
型號: ADR291GR-REEL
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 References
中文描述: 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PDSO8
封裝: MS-012AA, SOIC-8
文件頁數(shù): 14/15頁
文件大?。?/td> 199K
代理商: ADR291GR-REEL
REV. B
ADR290/ADR291/ADR292
–14–
A1
1 F
100k
V
OUT
GND
V
IN
ADR29x
+V
SENSE
A1 = 1/2 OP295
V
IN
R
LW
R
L
R
LW
+V
OUT
FORCE
Figure 6. Advantage of Kelvin Connection
Low Power, Low Voltage Reference For Data Converters
The ADR29x family has a number of features that makes it
ideally suited for use with A/D and D/A converters. The low
supply voltage required makes it possible to use the ADR290
and ADR291 with today
s converters that run on 3 V supplies
without having to add a higher supply voltage for the reference.
The low quiescent current (12
μ
A max) and low noise, tight
temperature coefficient, combined with the high accuracy of
the ADR29x makes it ideal for low power applications such
as hand-held, battery operated equipment.
One such ADC for which the ADR291 is well suited is the
AD7701. Figure 7 shows the ADR291 used as the reference for
this converter. The AD7701 is a 16-bit A/D converter with on-
chip digital filtering intended for the measurement of wide
dynamic range, low frequency signals such as those representing
chemical, physical or biological processes. It contains a charge
balancing (sigma-delta) ADC, calibration microcontroller with
on-chip static RAM, a clock oscillator and a serial communica-
tions port.
This entire circuit runs on
±
5 V supplies. The power dissipation
of the AD7701 is typically 25 mW and, when combined with
the power dissipation of the ADR291 (60
μ
W), the entire circuit
still consumes about 25 mW.
BP/
UP
CAL
V
REF
A
IN
AGND
AV
SS
AV
DD
DV
DD
SLEEP
MODE
DRDY
SCLK
SDATA
CS
CLKIN
CLKOUT
SC1
SC2
DGND
DV
SS
0.1 F
DATA
READY
READ
(TRANSMIT)
SERIAL
CLOCK
SERIAL
CLOCK
0.1 F
10 F
0.1 F
5V
ANALOG
SUPPLY
ANALOG
GROUND
ANALOG
INPUT
CALIBRATE
RANGES
SELECT
0.1 F
ADR291
GND
0.1 F
V
IN
V
OUT
+5V
ANALOG
SUPPLY
10 F
0.1 F
AD7701
Figure 7. Low Power, Low Voltage Supply Reference for
the AD7701
Voltage Regulator For Portable Equipment
The ADR29x family of references is ideal for providing a stable,
low cost and low power reference voltage in portable equipment
power supplies. Figure 8 shows how the ADR290/ADR291/
ADR292 can be used in a voltage regulator that not only has
low output noise (as compared to switch mode design) and
low power, but also a very fast recovery after current surges.
Some precautions should be taken in the selection of the out-
put capacitors. Too high an ESR (Effective Series Resistance)
could endanger the stability of the circuit. A solid tantalum
capacitor, 16 V or higher, and an aluminum electrolytic capacitor,
10 V or higher, are recommended for C1 and C2, respectively.
Also, the path from the ground side of C1 and C2 to the ground
side of R1 should be kept as short as possible.
ADR29x
V
OUT
GND
V
IN
0.1 F
LEAD-ACID
BATTERY
+
6V
CHARGER
INPUT
R1
402k
1%
R2
402k
1%
+C2
1000 F
ELECT
C1
68 F
TANT
+
5V, 100mA
IRF9530
R3
510k
OP20
TEMP
Figure 8. Voltage Regulator for Portable Equipment
相關(guān)PDF資料
PDF描述
ADR291GR-REEL7 Low Noise Micropower Precision Voltage References
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ADR291GT9 Low Noise Micropower Precision Voltage References
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