L6398 STMICROELECTRONICS [STMicroelectronics], L6398 Datasheet - Page 12

• Manufacturer Part Number: L6398
• Description: High voltage high and low side driver
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

Bootstrap driver
12/16
where Q
bootstrap DMOS and T
For example: using a power MOS with a total gate charge of 30nC 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 6.
Figure 7.
drop
has to be taken into account when the voltage drop on C
gate
is the gate charge of the external power MOS, R
Bootstrap driver with high voltage fast recovery diode
Bootstrap driver with internal charge pump
V
V
CC
CC
charge
charge
V
is the charging time of the bootstrap capacitor.
Doc ID 18199 Rev 3
drop
D
BOOT
is 5 μs. In fact:
=
HVG
LVG
HVG
30nC
-------------- - 120Ω
LVG
5μs
⋅
BOOT
OUT
BOOT
OUT
∼
H.V.
H.V.
0.7V
dson
BOOT
C
C
TO LOAD
TO LOAD
is the on resistance of the
BOOT
BOOT
is calculated: if this drop
L6398