DRV425 Datasheet, PDF (27/37 Pages) Texas Instruments – DRV425 Fluxgate Magnetic-Field Sensor

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DRV425
SBOS729 – OCTOBER 2015
8.2.2.1 Design Requirements
In order to measure the field gradient in the busbar, two DRV425 sensors are placed inside the hole at a well-
defined distance by mounting them on opposite sides of a PCB that is inserted in the hole. The measurement
range and resolution of this solution depends on the following factors:
• Busbar geometry: a wider busbar means a larger measurement range and lower resolution.
• Size of the hole: a larger diameter means a larger measurement range and lower resolution.
• Distance between the two DRV425 sensors: a smaller distance increases the measurement range and
resolution.
Each of these factors can be optimized to create the desired measurement range for a particular application.
Measurement ranges of ±250 A to ±1500 A are achievable with this approach. Larger currents are supported
with large busbar structures and minimized distance between the two DRV425 sensors. Use the parameters
listed in Table 3 as a starting point of the design.
DESIGN PARAMETER
Current range
Supply voltage, VDD
Reference voltage, V_REFIN
Table 3. Design Parameters
Up to ±1500 A
3.0 V to 5.5 V
VDD / 2
EXAMPLE VALUE
8.2.2.2 Detailed Design Procedure
Figure 73 shows the schematic diagram of a differential gradient field measurement circuit.
VDD
DRV2
DRV1
AINP
AINN
COMP1
U1
DRV425
VOUT
REFIN
REFOUT
OR
ERROR
VCM
COMP2
DRV2
DRV1
AINP
AINN
COMP1
COMP2
U2
DRV425
VOUT
REFIN
REFOUT
OR
ERROR
VDIFF
1 µF 1 µF
VDD
VDD
10 k:
10 k:
1 µF
+
±
U3
OPA320
R1
5.1 :
R2
5.1 :
R3
10 :
VREF
1 µF
1 µF
VDD
Figure 73. Schematic of a DRV425-Based Busbar Current-Sensing Circuit
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