ISL6209 INTERSIL [Intersil Corporation], ISL6209 Datasheet - Page 8

• Manufacturer Part Number: ISL6209
• Description: High Voltage Synchronous Rectified Buck MOSFET Driver
• Manufacturer: INTERSIL [Intersil Corporation]

Power Dissipation
Package power dissipation is mainly a function of the
switching frequency and total gate charge of the selected
MOSFETs. Calculating the power dissipation in the driver for
a desired application is critical to ensuring safe operation.
Exceeding the maximum allowable power dissipation level
will push the IC beyond the maximum recommended
operating junction temperature of 125°C. The maximum
allowable IC power dissipation for the SO-8 package is
approximately 800mW. When designing the driver into an
application, it is recommended that the following calculation
be performed to ensure safe operation at the desired
frequency for the selected MOSFETs. The power dissipated
by the driver is approximated as:
where f
and V
and Q
MOSFET selection and any external capacitance added to
the gate pins. The I
of the driver and is typically negligible.
P
=
f
sw
L
L
sw
(
represent the upper and lower gate rail voltage. Q
is the upper and lower gate charge determined by
1.5V
is the switching frequency of the PWM signal. V
U
Q
U
+
V
VCC
L
Q
L
V
)
+
CC
I
VCC
product is the quiescent power
8
V
CC
U
U
ISL6209
1000
900
800
700
600
500
400
300
200
100
0
FIGURE 7. POWER DISSIPATION vs FREQUENCY
0
Q
Q
U
L
200
= 200nC
=100nC
400
600
Q
Q
U
L
FREQUENCY (kHz)
=100nC
=50nC
800 1000 1200
1400
1600
Q
Q
Q
Q
U
L
U
L
=50nC
=50nC
=20nC
=50nC
1800 2000