DRV421_15 Datasheet, PDF (27/44 Pages) Texas Instruments – DRV421 Integrated Magnetic Fluxgate Sensor for Closed-Loop Current Sensing

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8 Application and Implementation
DRV421
SBOS704A – MAY 2015 – REVISED JULY 2015
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 Magnetic Core Design
The high sensitivity, low offset, and low noise of the DRV421 fluxgate sensor enable a high-performance closed-
loop current sensor module. For good module performance, an appropriate magnetic core design is required.
Table 3 lists the DRV421 and magnetic core specifications with relation to the overall current module
specifications.
Table 3. Current-Sensor Module Performance versus DRV421 Specifications and Magnetic Core
Performance
CURRENT SENSOR MODULE
PARAMETER
Offset and offset drift
Offset on start-up and after
overload condition
Noise
Linearity error
Gain error
Measurement range
Neighbor-current rejection
(crosstalk)
Bandwidth and gain flatness
Common-mode current rejection
(for fault current sensors)
PERFORMANCE DETERMINED BY:
DRV421 fluxgate sensor front-end: offset and offset drift
Magnetic core: magnetization (see the Magnetic Core Demagnetization section)
DRV421 fluxgate sensor front-end: noise
DRV421 fluxgate sensor front-end: AC open-loop gain
Magnetic core: Permeability, geometry, and actual number of compensation coil windings
1) DRV421 fluxgate sensor front-end: H-bridge peak current
2) Compensation coil: number of windings and resistance
3) Value of the external shunt resistor
Magnetic core: permeability, sensor gap design, and magnetic shielding
1) DRV421 fluxgate sensor front-end: AC open-loop gain setting
2) Magnetic core: high-frequency behavior of the core and inductance of the compensation coil
3) Value of the external shunt resistor
Magnetic core: permeability, actual position of the primary current conductors, and magnetic shielding
For further details, see also application report SLOA223, Designing with the DRV421: Closed Loop Current
Sensor Specifications.
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV421
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