參數(shù)資料
型號(hào)： REF192ESZ
廠商： ANALOG DEVICES INC
元件分類： 基準(zhǔn)電壓源/電流源
英文描述： Precision Micropower, Low Dropout Voltage References
中文描述： 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 2.5 V, PDSO8
封裝： ROHS COMPLIANT, MS-012AA, SOIC-8
文件頁(yè)數(shù)： 23/28頁(yè)
文件大?。?/td> 407K
代理商： REF192ESZ
REF19x Series
In applications where these devices are configured as low
dropout voltage regulators, these wiring voltage drops can
become a large source of error. To circumvent this problem,
force and sense connections can be made to the reference
through the use of an operational amplifier, as shown in Figure 29.
This method provides a means by which the effects of wiring
resistance voltage drops can be eliminated. Load currents flowing
through wiring resistance produce an I-R error (I
LOAD
× R
WIRE
) at
the load. However, the Kelvin connection overcomes the problem
by including the wiring resistance within the forcing loop of the
op amp. Because the op amp senses the load voltage, op amp
loop control forces the output to compensate for the wiring
error and to produce the correct voltage at the load. Depending
on the reference device chosen, operational amplifiers that can
be used in this application are the OP295, OP292, and OP183.
V
IN
Rev. I | Page 23 of 28
2
3
1
+V
SENSE
+V
FORCE
R
LW
1μF
100k
R
L
REF19x
GND
4
V
IN
V
OUT
A1 = 1/2 OP295
1/2 OP292
OP183
6
2
SLEEP
V
IN
R
LW
A1
3
0
Figure 29. A Low Dropout, Kelvin-Connected Voltage Reference
FAIL-SAFE 5 V REFERENCE
Some critical applications require a reference voltage to be
maintained at a constant voltage, even with a loss of primary
power. The low standby power of the REF19x series and the
switched output capability allow a fail-safe reference
configuration to be implemented rather easily. This reference
maintains a tight output voltage tolerance for either a primary
power source (ac line derived) or a standby (battery derived)
power source, automatically switching between the two as the
power conditions change.
The circuit in Figure 30 illustrates this concept, which borrows
from the switched output idea of Figure 28, again using the
REF19x device family output wire-OR capability. In this case,
since a constant 5 V reference voltage is desired for all
conditions, two REF195 devices are used for U1 and U2, with
their on/off switching controlled by the presence or absence of
the primary dc supply source, V
S
. V
BAT
is a 6 V battery backup
source that supplies power to the load only when V
S
fails. For
normal (V
S
present) power conditions, V
BAT
sees only the 15 μA
(maximum) standby current drain of U1 in its off state.
In operation, it is assumed that for all conditions, either U1 or
U2 is on, and a 5 V reference output is available. With this
voltage constant, a scaled down version is applied to the
Comparator IC U3, providing a fixed 0.5 V input to the negative
input for all power conditions. The R1 to R2 divider provides
a signal to the U3 positive input proportionally to V
S
, which
switches U3 and U1/U2, dependent upon the absolute level of
V
S
. In Figure 30, Op Amp U3 is configured as a comparator
with hysteresis, which provides clean, noise-free output
switching. This hysteresis is important to eliminate rapid
switching at the threshold due to V
S
ripple. Furthermore, the
device chosen is the AD820, a rail-to-rail output device. This
device provides HI and LO output states within a few mV of V
S
,
ground for accurate thresholds, and compatible drive for U2 for
all V
S
conditions. R3 provides positive feedback for circuit
hysteresis, changing the threshold at the positive input as
a function of the output of U3.
R5
100k
R6
100
R3
10M
AD820
C4
0.1μF
R2
100k
R1
1.1M
Q1
2N3904
+V
BAT
V
, V
COMMON
V
COMMON
C2
0.1μF
C1
0.1μF
5.000V
C3
1μF
U1
REF195
(SEE TABLE)
2
3
4
U2
(SEE TABLE)
2
3
4
+
6
6
+V
S
R4
900k
4
2
7
6
3
+
–
0
Figure 30. A Fail-Safe 5 V Reference
相關(guān)PDF資料
PDF描述
REF192ESZ-REEL Precision Micropower, Low Dropout Voltage References
REF192ESZ-REEL7 Precision Micropower, Low Dropout Voltage References
REF192FS-REEL Precision Micropower, Low Dropout Voltage References
REF192FS-REEL7 Precision Micropower, Low Dropout Voltage References
REF192FSZ Precision Micropower, Low Dropout Voltage References
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
REF192ESZ 制造商:Analog Devices 功能描述:Voltage Reference
REF192ESZ 制造商:Analog Devices 功能描述:VOLTAGE REFERENCE 2.5V
REF192ESZ-REEL 功能描述:IC VREF SERIES PREC 2.5V 8-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準(zhǔn) 系列:REF19 產(chǎn)品培訓(xùn)模塊:Voltage Reference Basics 標(biāo)準(zhǔn)包裝:100 系列:- 基準(zhǔn)類型:旁路，精度 輸出電壓:4.096V 容差:±0.075% 溫度系數(shù):50ppm/°C 輸入電壓:- 通道數(shù):1 電流 - 陰極:1µA 電流 - 靜態(tài):- 電流 - 輸出:10mA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:管件
REF192ESZ-REEL7 功能描述:IC VREF SERIES PREC 2.5V 8-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準(zhǔn) 系列:REF19 產(chǎn)品培訓(xùn)模塊:Voltage Reference Basics 標(biāo)準(zhǔn)包裝:100 系列:- 基準(zhǔn)類型:旁路，精度 輸出電壓:4.096V 容差:±0.075% 溫度系數(shù):50ppm/°C 輸入電壓:- 通道數(shù):1 電流 - 陰極:1µA 電流 - 靜態(tài):- 電流 - 輸出:10mA 工作溫度:0°C ~ 70°C 安裝類型:表面貼裝 封裝/外殼:8-SOIC（0.154"，3.90mm 寬） 供應(yīng)商設(shè)備封裝:8-SOIC 包裝:管件
REF192FS 功能描述:IC VREF SERIES PREC 2.5V 8-SOIC RoHS:否 類別:集成電路 (IC) >> PMIC - 電壓基準(zhǔn) 系列:REF19 標(biāo)準(zhǔn)包裝:3,000 系列:- 基準(zhǔn)類型:旁路，精度 輸出電壓:5V 容差:±0.5% 溫度系數(shù):100ppm/°C 輸入電壓:- 通道數(shù):1 電流 - 陰極:80µA 電流 - 靜態(tài):- 電流 - 輸出:15mA 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:TO-236-3，SC-59，SOT-23-3 供應(yīng)商設(shè)備封裝:SOT-23-3 包裝:帶卷 (TR) 其它名稱:LM4040CIM3-5.0MLTRLM4040CIM3-5.0MLTR-ND
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