Understanding and Selecting Isolation Transformers
Isolation Transformer Circuit
What is an isolation transformer?
Isolation / data transformers are used for isolation and voltage scaling in data line and power supply applications. Isolation transformers typically serve three main purposes:
Connecting circuits with grounds at different potentials – to prevent ground loops
Galvanic isolation – to prevent the flow of direct current (DC) between sections of circuits
Voltage transformation – to step up or step down from one voltage to another
Isolation transformers may be also be described as power-supply transformers, signal transformers, data-line transformers, communications transformers, interface transformers, data-interface transformers, industrial-communications transformers, and miniature transformers. This article discusses isolation / data transformers and the wide range of applications in which Coilcraft off-the-shelf isolation / data transformers can be used.
In what applications are isolation transformers used?
Isolation transformers are very versatile and well suited for many commercial and industrial power supply and data communications applications, including:
Low voltage (3.3 to 24 V) isolated DC-DC power supplies up to 7.2 Watts
Low-noise RS-485, RS-422, and RS-232 isolated serial communications data interfaces
PCMCIA thin card drivers up to 750 mW
Industrial and building automation and control systems
Multipoint data transmission systems
Isolated CAN interfaces
Isolated 4 – 20 mA current loops for process control
Transducer and actuator controls
Data acquisition (DAQ) systems
Isolated analog to digital conversion (ADC)
Serial Peripheral interfaces (SPI)
Inter-integrated Circuit (I2C) interfaces
Half-bridge, Full-bridge, and Push-pull low voltage isolated DC-DC power supplies
A high noise immunity serial communications standard such as RS-485 is best used in industrial environments. Unlike Ethernet, which has no built-in method of packet collision avoidance, the master / slave topology of RS-485 leads to more reliable behavior by avoiding data packet collisions and maintaining data integrity, which is crucial in noisy industrial environments.
Click to view all of Coilcraft's Isolation Transformers
What range of isolation transformers does Coilcraft manufacture?
Coilcraft has a variety of off-the-shelf isolation transformers with:
Input voltages of 3.3 to 24 Volts
Power ratings up to 7.2 Watts
Turns ratios from 1:1 to 1:5
Volt-time capabilities from 8.64 to 134 Vµs
Inductance from 16 to 1000 µH
Isolation from 1500 to 5000 Vrms
How do I select the Coilcraft isolation transformer that best fits my application requirements?
Coilcraft has developed a large selection of isolation transformers for the applications discussed above and in the many IC reference documents listed in the section below.
Find your Coilcraft isolation transformer here to match it with the IC for your application.