廬
APPLICATION BULLETIN
By R. Mark Stitt, (602) 746-7445
Mailing Address: PO Box 11400 鈥?Tucson, AZ 85734 鈥?Street Address: 6730 S. Tucson Blvd. 鈥?Tucson, AZ 85706
Tel: (602) 746-1111 鈥?Twx: 910-952-111 鈥?Telex: 066-6491 鈥?FAX (602) 889-1510 鈥?Immediate Product Info: (800) 548-6132
Make a 鈥?0V to +10V Adjustable Precision Voltage Source
Many situations require a precision voltage source which
can be adjusted through zero to both positive and negative
output voltages. An example is a bipolar power supply.
Have you ever adjusted your unipolar lab supply down to
0V, then swapped the output leads and adjusted it back up to
get a negative voltage output? What happened to your circuit
when the input from the low impedance source went open
circuit? Were you able to actually adjust the output to 0V, or
did a small voltage offset limit the range? This precision
bipolar voltage source can solve these problems.
Perhaps the most obvious implementation of a bipolar volt-
age source would be to use a bipolar voltage reference.
However, a simpler solution is to use a single voltage
reference and a precision unity-gain inverting amplifier. If
you use a precision difference amplifier for the unity-gain
inverting amplifier, the circuit requires just two chips and a
potentiometer.
To understand how the circuit works, first consider the 鈥?/div>
1.0V/V to +1.0V/V linear gain control amplifier shown in
Figure 1. An INA105 difference amplifier is used in a unity-
gain inverting amplifier configuration. A potentiometer is
connected between the input and ground. The slider of the
pot is connected to the noninverting input of the unity-gain
inverting amplifier. (The noninverting input of a unity-gain
inverting amplifier would normally be connected to ground.)
With the slider at the bottom of the pot, the circuit is a
normal precision unity-gain inverting amplifier with a gain
of 鈥?.0V/V
鹵0.01%
max. With the slider at the top of the
pot, the circuit is a normal precision voltage follower with a
gain of +1.0V/V
鹵0.001%
max. With the slider in the center,
there is equal positive and negative gain for a net gain of 0V/
V. The accuracy between 鈥?.0V/V and +1.0V/V will nor-
mally be limited by the accuracy of the pot. Precision 10-
turn pots are available with 0.01% linearity.
The 鈥?.0V/V to +1.0V/V linear gain control amplifier has
many applications. With the addition of a precision +10.0V
reference as shown in Figure 2, it becomes a 鈥?0V to +10V
adjustable precision voltage source.
INA105
Difference Amp
V
IN
2
R
1
25k鈩?/div>
R
3
25k鈩?/div>
R
2
25k鈩?/div>
6
V
OUT
=
+V
IN
to 鈥揤
IN
5
10k鈩?/div>
Linear
3
1
R
4
25k鈩?/div>
V
OUT
= +V
IN
, Slider at Top of Pot.
V
OUT
= 0V, Slider at Center of Pot.
V
OUT
= 鈥揤
IN
, Slider at Bottom of Pot.
FIGURE 1. 鈥?.0V/V to +1.0V/V Linear Gain Control Am-
plifier.
+V
S
2
V+
REF102
10V 6
Out
2
R
1
25k鈩?/div>
R
3
25k鈩?/div>
R
2
25k鈩?/div>
6
V
OUT
=
+10V to 鈥?0V
INA105
Difference Amp
5
Gnd
4
10k鈩?/div>
Linear
3
1
V
OUT
= +10V, Slider at Top of Pot.
V
OUT
= 0V, Slider at Center of Pot.
V
OUT
= 鈥?0V, Slider at Bottom of Pot.
R
4
25k鈩?/div>
FIGURE 2. 鈥?0V to +10V Adjustable Precision Voltage Source.
漏
1990 Burr-Brown Corporation
AB-006
Printed in U.S.A. April, 1990
AB-006相關(guān)型號(hào)PDF文件下載
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英文版
AB-001 - INCREASING INA117 DIFFERENTIAL INPUT RANGE
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AB-002 - MAKE A PRECISION CURRENT SOURCE OR CURRENT SINK
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AB-003 - VOLTAGE-REFERENCE FILTERS
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英文版
AB-004 - MAKE A PRECISION -10V REFERENCE
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AB-005 - Make A Precision -10V Reference
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AB-006 - Make a -10V to +10V Adjustable Precision Voltage So...
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AB-008 - AC COUPLING INSTRUMENTATION AND DIFFERENCE AMPLIFIE...
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AB-009 - SINGLE-SUPPLY OPERATION OF ISOLATION AMPLIFIERS
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AB-010 - -200V DIFFERENCE AMPLIFIER WITH COMMON-MODE VOLTAGE...
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AB-012 - BOOST ISO120 BANDWIDTH TO MORE THAN 100kHz
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AB-013 - INCREASING ADC603 INPUT RANGE
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AB-014 - INPUT OVERLOAD PROTECTION FOR THE RCV420 4-20mA CUR...
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AB-015 - EXTENDING THE COMMON-MODE RANGE OF DIFFERENCE AMPLI...
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AB-016 - BOOST AMPLIFIER OUTPUT SWING WITH SIMPLE MODIFICATI...
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AB-017 - Sallen-Key Low-Pass Filter Design Program
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AB-018 - 0 TO 20mA RECEIVER USING RCV420
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AB-019 - USING THE ADS7800 12 BIT ADC WITH UNIPOLAR INPUT SI...
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AB-020 - BURR-BROWN SPICE BASED MACROMODELS. REV. F
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