The current sensing can be done with a current transformer, hall sensor and also with analogue optocoupler and a shunt. The current sensing solution with a shunt and analog optocoupler can not be affected by magnetic fields. Also it is a very cost-effective solution which saves space on your pcb. This solution can be used for several applications with different currents without redesign.

Avago offers special developed optocoupler for current sensing. Some of them have additional features.

The output voltage of the HCPL-7510 is linear to the voltage at the shunt. It scales between 0V and the reference voltage. This gives the possibility for an easy adaption. This device is available in Dip8- package.

The HCPL-788J is available in an SO16-package. This device provides additional a fast short-circuit detection and also an overload fault detection. Different phases can be connected together to realize a very fast shutdown during a fault.

The required supply voltage on the power side in most cases can be taken from the gatedrive optocoupler.

For both products free evalboards are available.