Bootstrap driver

L6390

18/22

Equation 3

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

Equation 4

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

can be used.

Figure 7.

Bootstrap driver

V

drop

I

ch

e

V

drop

→

Q

gate

T

ch

e

arg

------------------R

dson

==

V

drop

30nC

5

µs

---------------

120

Ω 0.7V

∼

⋅

=

TO LOAD

D99IN1067

H.V.

HVG

ab

LVG

HVG

LVG

TO LOAD

H.V.

BOOT

V

CC

OUT

OUT

BOOT