DocID023386 Rev 5

9/14

A6387

Bootstrap driver

14

For example: using a power MOS with a total gate charge of 30 nC, the drop on the

bootstrap DMOS is about 1 V, if the Tcharge is 5 s. In fact:

Equation 3

Vdrop should be taken into account when the voltage drop on CBOOT is calculated: if this drop

is too high, or the circuit topology doesn’t allow a sufficient charging time, an external diode

can be used.

Figure 5. Bootstrap driver

Vdrop

30nC

5

s

--------------- 125

 0.8V





=