DRV401-Q1 Datasheet, PDF (17/39 Pages) Texas Instruments – DRV401-Q1 Sensor Signal Conditioning Device for Closed-Loop Magnetic Current Sensor

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DRV401-Q1
SBOS814 – DECEMBER 2016
Feature Description (continued)
If the core material is magnetized in one direction, a long and a short charge time result because the probe
current through the inductors generates a field that subtracts or adds to the flux in the probe core, driving the
probe core out of saturation or further into saturation, as shown in Figure 38. The current into the probe is limited
by the voltage drops across the probe driver resistors.
B
H
V (IS1)
V (PWM)/10
500 ns/div
An external magnetic flux (H) generated from the primary current (I_PRIM) shifts the hysteresis curve of the magnetic
field probe in the H-axis and the probe loop generates a nonsymmetrical duty cycle.
Figure 38. Magnetic Probe, Hysteresis, and Duty Cycle With External Magnetic Field
The DRV401-Q1 device continuously monitors the logic magnetic flux polarity state. In the case of distortion
noise and excessive overload that can fully saturate the probe, the overload control circuit recovers the probe
loop. During an overload condition, the probe oscillation frequency increases to approximately 1.6 MHz until
limited by the internal timing control.
In an overload condition, the compensation current (I_COMP) driver cannot deliver enough current into the sensor
secondary winding, so the magnetic flux in the sensor main core becomes uncompensated.
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