DRV425 Datasheet, PDF (21/37 Pages) Texas Instruments – DRV425 Fluxgate Magnetic-Field Sensor

www.ti.com
DRV425
SBOS729 – OCTOBER 2015
Feature Description (continued)
Both the ERROR and OR pins are open-drain outputs that require an external pullup resistor. Connect both pins
together with a single pullup resistor to provide a single diagnostic flag, if desired.
Based on the DRV425 System Parameter Calculator, SLOC331, for a design for a ±2-mT magnetic field input
range with a supply of 5 V (±5%), a shunt resistor value of 22 Ω is selected and Figure 63 shows the status of
the diagnostic flags in the resulting three operation ranges.
Sensor Saturation: B > 3.6 mT
(OR = 0, ERROR = 0)
4
3
Magnetic Overrange: 2 mT < ^3.6 mT
(OR = 0, ERROR = 1)
2
1
0
Designated Operating Range: 2 2%^^2 mT
(OR = 1, ERROR = 1)
1
2
Magnetic Overrange: 3.6 2%^< 2 mT
3
(OR = 0, ERROR = 1)
4
Sensor Saturation: B < 3.6 mT
(OR = 0, ERROR = 0)
Figure 63. Magnetic Field Range of the DRV421 (VDD = 5 V and R_SHUNT = 22 Ω)
With the proper R_SHUNT value, the differential amplifier output rails and activates the overrange flag (OR = 0)
when the magnetic field exceeds the designated operating range. For fields that exceed the measurement range
of the DRV425 by ≥ 1.6 mT, the fluxgate is permanently saturated and the ERROR pin is pulled low. In this
condition, the fluxgate sensor does not provide a valid output value and, therefore, the output VOUT of the
DRV425 must be ignored. In applications where the ERROR pin cannot be separately monitored, combining the
VOUT and ERROR outputs is recommended (as shown in Figure 64) to indicate a magnetic field outside of the
sensor range by pulling the output of the DRV425 to ground.
5V
RSHUNT
DRV2
DRV1
AINP
AINN
COMP1
COMP2
Device
VOUT
REFIN
REFOUT
OR
ERROR
1 k:
1 µF 1 µF
5V
Figure 64. Field Overrange Detection Using a Combined VOUT and ERROR Pin
Copyright © 2015, Texas Instruments Incorporated
Product Folder Links: DRV425
Submit Documentation Feedback
21