SBOS704B May 2015 – March 2016 DRV421
PRODUCTION DATA.
The DRV421 unique, integrated fluxgate has a very high sensitivity to magnetic fields in order to enable design of a closed-loop current sensor with best-in-class precision and linearity. Observe proper PCB layout techniques because any current-conducting wire in the direct vicinity of the DRV421 generates a magnetic field that may distort measurements. Common passive components and some PCB plating materials contain ferromagnetic materials that are magnetizable. For best performance, use the following layout guidelines:
Ferrite beads in series to the power-supply connection reduce interaction with other circuits powered from the same supply voltage source. However, to prevent influence of the magnetic fields if ferrite beads are used, do not place them next to the DRV421.
The reference output (REFOUT pin) refers to GND. Use a low-impedance and star-type connection to reduce the driver current and the fluxgate sensor current modulating the voltage drop on the ground track. The REFOUT and VOUT outputs are able to drive some capacitive load, but avoid large direct capacitive loading because of increased internal pulse currents. Given the wide bandwidth of the shunt sense amplifier, isolate large capacitive loads with a small series resistor.
Solder the exposed PowerPAD, on the bottom of the package to the ground layer because the PowerPAD is internally connected to the substrate that must be connected to the most-negative potential.
Figure 71 illustrates a generic layout example that highlights the placement of components that are critical to the DRV421 performance. For specific layout examples, see SLOU409, DRV421EVM Users Guide, and TIDUA92, TIPD196 Design Guide.