L6390_12 STMICROELECTRONICS [STMicroelectronics], L6390_12 Datasheet - Page 19

• Manufacturer Part Number: L6390_12
• Description: High-voltage high/low-side driver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

L6390
where Q
the bootstrap DMOS and T
For example: using a Power MOSFET with a total gate charge of 30 nC, the drop on the
bootstrap DMOS is about 1 V, if the T
Equation 4
V
is too high, or the circuit topology doesn’t allow a sufficient charging time, an external diode
can be used.
Figure 10. Bootstrap driver
drop
V
CC
should be taken into account when the voltage drop on C
gate
D
is the gate charge of the external Power MOSFET, R
BOOT
a
HVG
LVG
charge
BOOT
OUT
Doc ID 14493 Rev 7
V
H.V.
is the charging time of the bootstrap capacitor.
drop
charge
=
C
TO LOAD
BOOT
30nC
-------------- -
5μs
is 5 μs. In fact:
V
⋅
CC
120Ω 0.7V
∼
b
HVG
LVG
BOOT
dson
is calculated: if this drop
is the on-resistance of
BOOT
OUT
Bootstrap driver
H.V.
D99IN1067
C
TO LOAD
BOOT
19/26