DRV401-Q1 Datasheet, PDF (24/39 Pages) Texas Instruments – DRV401-Q1 Sensor Signal Conditioning Device for Closed-Loop Magnetic Current Sensor

DRV401-Q1
SBOS814 – DECEMBER 2016
8 Application and Implementation
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NOTE
Information in the following applications sections is not part of the TI component
specification, and TI does not warrant its accuracy or completeness. TI’s customers are
responsible for determining suitability of components for their purposes. Customers should
validate and test their design implementation to confirm system functionality.
8.1 Application Information
8.1.1 Functional Principle of Closed-Loop Current Sensors with Magnetic Probe Using the DRV401-Q1
Device
Closed-loop current sensors measure current over wide frequency ranges, including dc. These types of devices
offer a contact-free method and an excellent galvanic isolation performance combined with high resolution,
accuracy, and reliability.
At dc and in low-frequency ranges, the magnetic field induced from the current in the primary winding is
compensated by a current flowing through a compensation winding. A magnetic field probe, located in the
magnetic core loop, detects the magnetic flux. This probe delivers the signal to the amplifier that drives the
current through the compensation coil, bringing the magnetic flux back to zero. This compensation current is
proportional to the primary current, relative to the winding ratio.
In higher-frequency ranges, the compensation winding acts as the secondary winding in the current transformer,
while the H-bridge compensation driver is rolled off and provides low output impedance.
A difference amplifier senses the voltage across a small shunt resistor that is connected to the compensation
loop. This difference amplifier generates the output voltage that is referenced to REF_IN and is proportional to the
primary current. The Functional Block Diagram shows the DRV401-Q1 device used as a compensation current
sensor.
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