Download APPLICATION BULLETIN

Survey
yes no Was this document useful for you?
   Thank you for your participation!

* Your assessment is very important for improving the work of artificial intelligence, which forms the content of this project

Transcript
APPLICATION BULLETIN
®
Mailing Address: PO Box 11400 • Tucson, AZ 85734 • Street Address: 6730 S. Tucson Blvd. • Tucson, AZ 85706
Tel: (602) 746-1111 • Twx: 910-952-111 • Telex: 066-6491 • FAX (602) 889-1510 • Immediate Product Info: (800) 548-6132
LEVEL SHIFTING SIGNALS
WITH DIFFERENTIAL AMPLIFIERS
by David Jones, (602) 746-7696
The INA105 is a unity gain differential amplifier consisting
of a premium grade operational amplifier and an on-chip
precision resistor network. The self-contained INA105 makes
it ideal for many applications. One such application is
precision level shifting.
“Ref” input. Therefore, VREF may take on any arbitrary value
that will not saturate the INA105 amplifier’s output. In the
case of the circuit in Figure 1, VREF = VSHIFT, yielding an
output of EO = E2 – E1 +VSHIFT.
Precision fixed level shifting can be easily accomplished by
the use of a voltage reference source such as the REF102. A
REF102 used with an additional INA105 can be used to
provide an accurate, low drift, +5V reference to drive the
“Ref” pin of the differentially connected INA105 as shown
in Figure 2. If, for example, the input signal is a bipolar ±5V
signal, the output will be level shifted to a unipolar 0-10V
signal. The same reference circuit also has –5V available
and may thus be used for the opposite conversion from
unipolar 0-10V to bipolar ±5V signals. (Request PDS-1018
for INA105 and PDS-900 for REF102.)
Figure 1 shows a general case of a unity gain differential
amplifier that performs a signal level shift proportional to
the voltage VSHIFT appearing on pin 3 of the OPA27. An
operational amplifier is used to drive the INA105’s “Ref”
pin (pin 1) with a low impedance source to preserve true
differential operational of the INA105.
A basic understanding of the circuit operation can be gained
by considering the INA105 as a three input summing amplifier. The voltage transfer function is then EOUT = E2 – E1 +
VREF. As this relation shows, the output will respond to a
difference signal and algebraically add the voltage at the
E1
2
E1
5
2
5
–
6
6
E2
3
EO
E2
3
EO
+
+VCC
2
2
VSHIFT
3
2
OPA27
6 1
6 1
INA105
REF102
INA105
1kΩ
FIGURE 1. Level Shifting Circuit Using the INA105’s VREF
Pin.
5
4
–5V
–
6
+
INA105
1
3
FIGURE 2. Precision Level Shift Circuit from a Fixed Voltage Reference.
©
SBOA038
1994 Burr-Brown Corporation
www.BDTIC.com/TI
AB-087
Printed in U.S.A. January, 1994
IMPORTANT NOTICE
Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue
any product or service without notice, and advise customers to obtain the latest version of relevant information
to verify, before placing orders, that information being relied on is current and complete. All products are sold
subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those
pertaining to warranty, patent infringement, and limitation of liability.
TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in
accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent
TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily
performed, except those mandated by government requirements.
Customers are responsible for their applications using TI components.
In order to minimize risks associated with the customer’s applications, adequate design and operating
safeguards must be provided by the customer to minimize inherent or procedural hazards.
TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent
that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other
intellectual property right of TI covering or relating to any combination, machine, or process in which such
semiconductor products or services might be or are used. TI’s publication of information regarding any third
party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.
Copyright  2000, Texas Instruments Incorporated
www.BDTIC.com/TI
Document related concepts

Mains electricity wikipedia, lookup

Public address system wikipedia, lookup

Buck converter wikipedia, lookup

Switched-mode power supply wikipedia, lookup

Opto-isolator wikipedia, lookup

Alternating current wikipedia, lookup

Voltage optimisation wikipedia, lookup

Power electronics wikipedia, lookup

Voltage regulator wikipedia, lookup

Schmitt trigger wikipedia, lookup

Resistive opto-isolator wikipedia, lookup

Rectifier wikipedia, lookup

Stray voltage wikipedia, lookup

Current source wikipedia, lookup

Pulse-width modulation wikipedia, lookup

Variable-frequency drive wikipedia, lookup

Islanding wikipedia, lookup

Wien bridge oscillator wikipedia, lookup

Amplifier wikipedia, lookup

Tube sound wikipedia, lookup

Heterodyne wikipedia, lookup

Regenerative circuit wikipedia, lookup

Audio power wikipedia, lookup

Ground loop (electricity) wikipedia, lookup

Two-port network wikipedia, lookup

Analog-to-digital converter wikipedia, lookup

Oscilloscope history wikipedia, lookup

Dynamic range compression wikipedia, lookup

Scattering parameters wikipedia, lookup

Signal-flow graph wikipedia, lookup

Negative feedback wikipedia, lookup