link to page 18 link to page 18 link to page 18 Coreless, High Precision, Hall-Effect Current Sensor ICACS37612with Common-Mode Field Rejection and High Bandwidth (240 kHz)APPLICATION INFORMATIONTypical Application – Busbar SensingFigure 18: Busbar current sensing application – reference busbar design The ACS37612 is ideal for busbar current sensing applications. evaluation board designed to measure ±1000 A. For a given current flowing through the busbar, the magnitude of Note: Comparing the busbar described in Figure 18 to a bare bus- the differential magnetic field sensed by the IC will depend on bar (without notch), the busbar with the 3 mm notch increased the the air gap between the busbar and the IC. overall impedance by less than 1 µΩ, increasing busbar tempera- Adding a notch (width reduction) to the busbar at the location ture by only few degrees during testing. where the sensor is placed significantly increases the magnitude Skin Effect Consideration of the magnetic field, improving SNR. Keeping the notch length short (2 to 3 mm) results in virtually no increase in the resistance Skin effect in the conductor will tend to reduce the magnitude of the busbar or degradation of its thermal performance. of the differential magnetic field measured by the IC at high frequencies (coupling factor) and therefore will influence the Different busbar and notch dimensions can be used to optimize bandwith of the system and response time to transient current. system performance and respond to application constraints. Skin effect will depend on busbar dimensions, sensor mounting Figure 18 and Table 1 highlight the dimensions of an Allegro orientation, and distance between the busbar and the IC. Table 1: Current range based on reference busbar design:Busbar ApplicationMaximum Current (A) Coupling Factor at 2.5 mm Crystal Air Gap [1] Differential Field (G) IC Sensitivity (mV/G) 18 × 3 mm Busbar + 3 mm Notch ±1000 0.19 ±190 10 [1] Crystal air gap is defined as the distance from the busbar surface to the device sensing elements (considering active area depth). 18 Allegro MicroSystems 955 Perimeter Road Manchester, NH 03103-3353 U.S.A. www.allegromicro.com