DGD0506

Document number: DS38740 Rev. 8 - 3

12 of 14

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June 2021

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DGD0506

Application Information (continued)

Pre-Bias Resistor between Vs and COM

This technique eliminates the inrush current, altogether, by pre-charging the capacitor to a value close to VCC before the DGD0506 is enabled and

an input signal is applied. By pre-charging the capacitor to VCC only a small steady state current flows through the internal diode eliminating the

need for any external diode. The recommended range for the Rs is 10kΩ to 100kΩ.

External Diode and Resistor

To enable appropriate current sharing and limit the internal bootstrap current to less than 400mA, a Schottky diode must be used as an external

diode. The voltage drop across the external diode and resistor must be limited to 2.4V, to limit the internal diode’s current share to <400mA. Hence

it is important to choose an appropriate external diode and resistor combination. At any observed inrush current peak, it is important that the

combined voltage drop of the external resistor and diode is less than 2.4V.

For internal diode current to be <400mA; (IINRUSH * REXT) + (VfEXT @ IINRUSH) < 2.4V.

Figure 30. Current into the boost-strap capacitance is

shared between the external diode and the internal Diode

Figure 29. Inrush current is greatly limited by pre-

charging the boost-strap Capacitor through Rs