What different between Istart and Inrush current for ADM1272?

Hi ADI Expert,

I am confused about this.  What different between Istart and Inrush current for ADM1272?

Thanks.

Andy Yang.

    •  Analog Employees 
    on Jan 7, 2020 4:26 PM 10 months ago

    Hi Andy,

    Inrush current is the amount of current that flows to the load during the startup voltage ramp. It is usually only the capacitor charging current (C*dv/dt), though sometimes there is a resistive load as well. Inrush is normally controlled by the capacitor on the DVDT pin of the ADM1272, which limits the dv/dt of the FET gate and source pins. ISTART is the current limit set by the ISTART pin. If inrush current exceeds this limit he ADM1272 will control the gate of the FET during startup to prevent more than this limit from flowing. Most of the time, however we place a suitably large capacitor on the DVDT pin to keep inrush current less than 1/2 of the ISTART limit. ISTART is only engaged during a fault situation, like startup into a short circuit.

    Thanks!

    -Nathan