參數(shù)資料
型號： REF195GS-REEL7
廠商： ANALOG DEVICES INC
元件分類： 基準電壓源/電流源
英文描述： Precision Micropower, Low Dropout Voltage References
中文描述： 1-OUTPUT THREE TERM VOLTAGE REFERENCE, 5 V, PDSO8
封裝： MS-012AA, SOIC-8
文件頁數(shù)： 21/28頁
文件大?。?/td> 407K
代理商： REF195GS-REEL7
REF19x Series
One caveat to this approach is that 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.
Rev. I | Page 21 of 28
100
1μF
1k
1μF
–V
REF
REF19x
GND
4
V
IN
V
OUT
100k
SLEEP
TTL/CMOS
A1 = 1/2 OP295,
1/2 OP291
V
IN
10k
2N3906
3
6
2
SLEEP
10k
+5V
–5V
A1
0
Figure 24. Negative Precision Voltage Reference Uses No Precision Resistors
STACKING REFERENCE ICS FOR
ARBITRARY OUTPUTS
Some applications may require two reference voltage sources
that are a combined sum of standard outputs. The circuit shown
in Figure 25 shows how this stacked output reference can be
implemented.
R1
3.9k
(SEE TEXT)
C1
0.1μF
+VS
V
S
> V
OUT2
+ 0.15V
V
COMMON
V
COMMON
OUTPUT TABLE
U1/U2
REF192/REF192
REF192/REF194
REF192/REF195
V
OUT1
(V)
2.5
2.5
2.5
V
OUT2
(V)
5.0
7.0
7.5
+V
OUT2
C2
1μF
C3
0.1μF
+V
OUT1
C4
1μF
U2
(SEE TABLE)
2
6
3
4
U1
REF19x
(SEE TABLE)
2
6
3
4
+
+
V
O
(U2)
V
O
(U1)
0
Figure 25. Stacking Voltage References with the REF19x
Two reference ICs are used, fed from a common unregulated
input, V
S
. The outputs of the individual ICs are connected in
series, as shown in Figure 25, which provide two output
voltages, V
OUT1
and V
OUT2
. V
OUT1
is the terminal voltage of U1,
while V
OUT2
is the sum of this voltage and the terminal voltage
of U2. U1 and U2 are chosen for the two voltages that supply
the required outputs (see Output Table in Figure 25). If, for
example, both U1 and U2 are REF192s, the two outputs are 2.5 V
and 5.0 V.
While this concept is simple, some cautions are needed. Since
the lower reference circuit must sink a small bias current from
U2 (50 μA to 100 μA), plus the base current from the series
PNP output transistor in U2, either the external load of U1 or
R1 must provide a path for this current. If the U1 minimum
load is not well defined, Resistor R1 should be used, set to a
value that conservatively passes 600 μA of current with the
applicable V
OUT1
across it. Note that the two U1 and U2
reference circuits are locally treated as macrocells, each having
its own bypasses at input and output for best stability. Both U1
and U2 in this circuit can source dc currents up to their full
rating. The minimum input voltage, V
S
, is determined by the
sum of the outputs, V
OUT2
, plus the dropout voltage of U2.
A related variation on stacking two 3-terminal references is
shown in Figure 26, where U1, a REF192, is stacked with a
2-terminal reference diode, such as the AD589. Like the
3-terminal stacked reference above, this circuit provides two
outputs, VOUT1 and VOUT2, which are the individual terminal
voltages of D1 and U1, respectively. Here this is 1.235 V and 2.5 V,
which provides a V
OUT2
of 3.735 V. When using 2-terminal
reference diodes, such as D1, the rated minimum and maximum
device currents must be observed, and the maximum load
current from V
OUT1
can be no greater than the current setup by
R1 and V
O
(U1). When V
O
(U1) is equal to 2.5 V, R1 provides a
500 μA bias to D1, so the maximum load current available at
V
OUT1
is 450 μA or less.
D1
AD589
R1
4.99k
(SEE TEXT)
C1
0.1μF
+V
V
S
> V
OUT2
+ 0.15V
V
COMMON
V
COMMON
+V
3.735V
C2
1μF
+V
1.235V
C3
1μF
U1
REF192
2
6
3
4
+
+
V
O
(U1)
V
O
(D1)
0
Figure 26. Stacking Voltage References with the REF192
PRECISION CURRENT SOURCE
In low power applications, the need often arises for a precision
current source that can operate on low supply voltages. As shown
in Figure 27, any one of the devices in the REF19x family of
references can be configured as a precision current source.
The circuit configuration illustrated is a floating current source
with a grounded load. The output voltage of the reference is
bootstrapped across R
SET
, 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 30 μA) to approximately 30 mA. The low dropout
voltage of these devices maximizes the current source’s output
voltage compliance without excess headroom.
相關(guān)PDF資料
PDF描述
REF195GSZ Precision Micropower, Low Dropout Voltage References
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
REF195GSZ 功能描述:IC VREF SERIES PREC 5V 8-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準 系列:REF19 標準包裝:3,000 系列:- 基準類型:旁路，精度 輸出電壓:3V 容差:±0.5% 溫度系數(shù):100ppm/°C 輸入電壓:- 通道數(shù):1 電流 - 陰極:82µA 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:6-TSSOP（5 引線），SC-88A，SOT-353 供應商設備封裝:SC-70-5 包裝:帶卷 (TR) 其它名稱:296-20888-2
REF195GSZ 制造商:Analog Devices 功能描述:Voltage Reference IC
REF195GSZ-REEL 功能描述:IC VREF SERIES PREC 5V 8-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準 系列:REF19 產(chǎn)品培訓模塊:Voltage Reference Basics 標準包裝:100 系列:- 基準類型: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） 供應商設備封裝:8-SOIC 包裝:管件
REF195GSZ-REEL7 功能描述:IC VREF SERIES PREC 5V 8-SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 電壓基準 系列:REF19 產(chǎn)品培訓模塊:Voltage Reference Basics 標準包裝:100 系列:- 基準類型: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） 供應商設備封裝:8-SOIC 包裝:管件
REF196 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Micropower, Low Dropout Voltage References
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