PRODUCTDESCRIPTION

Using Allegro Current Sensors in Current Divider Configurations for Extended Measurement Range

INTRODUCTION The central element of all Allegro current sensors is a precision linear Hall-effect-based magnetic field sensor circuit. For standard sensors, the cir- cuit is bidirectional, as shown in figure 1, allow- ing current flow in either direction. The magnetic field generated by the current is sensed by the integrated Hall IC and converted by Richard Dickinson and Andreas Friedrich ABSTRACT Allegro

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current sensors are characterized by innovative packaging technologies that integrate a low-resistance copper primary current conduc- tion path into the package. While this enhances the performance of the application in many ways, there are current level limitations imposed by packaging considerations. This application note describes simple meth-ods for increasing the measurable current range. These methods involve splitting the path of the current being sensed. Various options of devices and circuits are described.

Figure 1. Current Divider Configurations. The Allegro current sensor primary conductor terminals can be con-nected directly to a bus bar for higher-current applications. Panel A shows this configuration, with the ACS75x– PSF current sensor package option used. For lower current applications, the current sensor can be connected to printed circuit board traces. Panel B shows this configuration, using the ACS75x–PFF package option. For standard sensors, current can be passed in either direction.(A) Higher Current Applications(B) Lower Current Applications

AN295036, Rev. 1