STEVAL-ISF003V1 Low standby losses power front-end with inrush current-limitation

The STEVAL-ISF003V1 evaluation board allows the inrush-current which charges a DC bus capacitor to be limited to comply with the IEC 61000-3-3 standard. This inrush-current limitation is based on a soft-start procedure of the mixed bridge diodes and SCRs rectifier using progressive phase control at board start-up.

This solution can also drastically reduce standby losses as the DC bus can be totally disconnected from the AC mains when it does not have to operate. DC bus deactivation is simply achieved by turning off SCRs, without requiring an additional relay to open the circuit in standby.

The steady-state losses are also reduced, thanks to the removal of the NTC / PTC resistor traditionally used to limit inrush-current. Therefore, no relay is required to bypass this resistor as it is no longer used.