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參數(shù)資料
| 型號： | REF193GP |
| 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, 3 V, PDIP8 |
| 封裝： | PLASTIC, DIP-8 |
| 文件頁數(shù)： | 20/23頁 |
| 文件大?。?/td> | 238K |
| 代理商： | REF193GP |
REF19x Series
–20–
REV. D
Switched Output 5 V/3.3 V Reference
Applications often require digital control of reference voltages,
selecting between one stable voltage and a second. With the
sleep feature inherent to the REF19x series, switched output
reference configurations are easily implemented with relatively
little additional hardware.
The circuit of Figure 22 illustrates the general technique, which
takes advantage of the output “wire-OR” capability of the
REF19x device family. When OFF, a REF19x device is effec-
tively an open circuit at the output node with respect to the
power supply. When ON, a REF19x device can source current
up to its current rating, but sink only a few
μ
A (essentially just
the relatively low current of the internal output scaling divider).
As a result, for two devices wired together at their common
outputs, the output voltage is simply that of the ON device.
The OFF state device will draw a small standby current of
15
μ
A (max), but otherwise will not interfere with operation of
the ON device, which can operate to its full current rating.
Note that the two devices in the circuit conveniently share
both input and output capacitors, and with CMOS logic
drive, it is power efficient.
Using dissimilar REF19x series devices with this configuration
allows logic selection between the U1/U2 specified terminal
voltages. For example, with U1 (a REF195) and U2 (a REF196),
as noted in the table, changing the CMOS compatible V
C
logic
control voltage from HI to LO selects between a nominal output
of 5.000 V and 3.300 V and vice versa. Other REF19x family
units can also be used for U1/U2, with similar operation in a
logic sense, but with outputs as per the individual paired devices
(see table, again). Of course, the exact output voltage tolerance,
drift and overall quality of the reference voltage will be consis-
tent with the grade of individual U1 and U2 devices.
U1
(SEE TABLE)
C1
0.1
m
F
+V
S
= 6V
V
IN
COMMON
V
COMMON
+V
OUT
C2
1
m
F
U2
(SEE TABLE)
3
4
1
2
U3B
74HC04
U3A
74HC04
V
C
OUTPUT TABLE
V
OUT
(V)
5.0
3.3
4.5
5.0
V
C
*
HI
LO
HI
LO
U1/U2
REF195/
REF196
REF194/
REF195
* CMOS LOGIC LEVELS
Figure 22. Switched Output Reference
U1
REF192
R1
(SEE TEXT)
C1
0.1
m
F
+V
S
V
S
> V
OUT2
+0.15V
V
IN
COMMON
V
COMMON
+V
3.735V
V
O
(U1)
C2
1
m
F
D1
AD589
V
O
(D1)
C3
1
m
F
+V
1.235V
Figure 20. Stacking Voltage References with the REF19x
A Precision Current Source
Many times, in low power applications, the need arises for a
precision current source that can operate on low supply volt-
ages. As shown in Figure 21, 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 reference’s output
voltage is bootstrapped across R
SET
, which sets the output cur-
rent into the load. With this configuration, circuit precision is
maintained for load currents in the range from the reference’s
supply current (typically, 30
μ
A) to approximately 30 mA. The
low dropout voltage of these devices maximizes the current
source’s output voltage compliance without excess headroom.
1
m
F
REF19x
V
IN
GND
V
REF
SLEEP
V
IN
I
SY
ADJUST
R1
P1
R
L
R
SET
I
OUT
V
IN
I
OUT
R
L
(MAX) + V
SY
(MIN)
OUT
I
OUT
= V
SY
(REF19x)
R
SET
V
OUT
>> I
SY
R
SET
E.G. REF195 : V
OUT
= 5V
I
= 5mA
R1 = 953
V
P1 = 100
V
, 10-TURN
Figure 21. A Low Dropout, Precision Current Source
The circuit’s governing equations are:
V
IN
=
I
OUT
×
R
L
(
max
)
+
V
SY
(
min
,
REF
19
x
)
I
OUT
=
V
OUT
R
SET
V
OUT
R
SET
+
I
SY
(
REF
19
x
)
I
SY
(
REF
19
x
)
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| REF195GBC | Precision Micropower, Low Dropout, Voltage References |
| REF196GBC | Precision Micropower, Low Dropout, Voltage References |
| REF196GP | Precision Micropower, Low Dropout, Voltage References |
| REF198GRU | Precision Micropower, Low Dropout, Voltage References |
| REF198GS | Precision Micropower, Low Dropout, Voltage References |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| REF193GRU | 制造商:AD 制造商全稱:Analog Devices 功能描述:Precision Micropower, Low Dropout, Voltage References |
| REF193GRU4 | 制造商:未知廠家 制造商全稱:未知廠家 功能描述:REF19x Series: Precision Micropower. Low Dropout. Low Voltage References Data Sheet (Rev. E. 1/03) |
| REF193GS | 制造商:Analog Devices 功能描述:V-Ref Precision 3V 30mA 8-Pin SOIC N Tube 制造商:Rochester Electronics LLC 功能描述:MICROPOWER VOLTAGE REF - Bulk 制造商:Analog Devices 功能描述:Voltage Regulator IC Voltage Regulator T |
| REF193GS-REEL | 制造商:Analog Devices 功能描述:V-Ref Precision 3V 30mA 8-Pin SOIC N T/R |
| REF193GS-REEL7 | 制造商:Analog Devices 功能描述:V-REF PRECISION 3V 30MA 8SOIC N - Tape and Reel |
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