IC transducer for AC and DC isolated current measurement to 100 KHz

Minisens integrates, within one mixed signal ASIC, Hall-effect sensors with a magnetic concentrator to allow direct current measurement without the need for an additional magnetic core. The non-contact measurement enables an almost unlimited current level as it eliminates the need for current to flow through the device. The only limiting factor is the thermal capacities of the primary conductor. The current can be carried either by a track (or tracks) located on a PCB underneath the Minisens, or by a cable or bus bar under or above the IC. The unlimited design possibilities for the primary conductor allow current measurement up to 70 A or even higher.



Many parameters of the ASIC can be configured by on-chip non-volatile memory: adjustment of the transducer’s gain, offset, polarity, temperature drift and gain algorithm (proportional to, or independent of VDD). Two outputs are available: one filtered, to limit the noise bandwidth; and one unfiltered, which has a response time of less than 3 microseconds.



The degree of electrical isolation and output sensitivity can be increased by the PCB design – for example, a primary track on the opposite side of the IC gives best isolation; a track on the same side gives the highest sensitivity. Mounted as part of a standard PCB assembly process, manufacturing costs are minimized.

The Minisens operates from a single 5V supply. To minimise power consumption an optional input pin can be used to switch the Minisens into standby mode. The transducer is manufactured with a CMOS process and assembled in a SO8-IC package.



The combination of different IC configurations and flexible PCB designs results in very versatile and attractively priced current transducer solutions. This opens up opportunities for applications such as white goods or air conditioning to benefit from isolated current measurement, which previously was not feasible. Minisens will also enable enhanced motor control to produce energy savings where other methods such as the shunt have traditionally been used.