L6386AD
Bootstrap driver
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 µs. In fact:
Vdrop =
3----0----n---C---
5µs
⋅
125Ω ∼0.8V
Vdrop has to 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 4. Bootstrap driver
DBOOT
VS
HVG
LVG
a
VBOOT
H.V.
VOUT
VS
CBOOT
TO LOAD
HVG
LVG
b
VBOOT
H.V.
VOUT
CBOOT
TO LOAD
D99IN1056
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