FAN3268TMX Fairchild Semiconductor, FAN3268TMX Datasheet - Page 13

• Manufacturer Part Number: FAN3268TMX
• Description: IC BRIDGE DVR P/N-CH 2A 8SOIC
• Manufacturer: Fairchild Semiconductor

Specifications of FAN3268TMX

• Configuration: Half Bridge
• Input Type: Inverting and Non-Inverting
• Delay Time: 14ns
• Current - Peak: 3A
• Number Of Configurations: 1
• Number Of Outputs: 2
• Voltage - Supply: 4.5 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Operating Temperature (max): 125C
• Operating Temperature (min): -40C
• Pin Count: 8
• Mounting: Surface Mount
• Package Type: SOIC N
• Case Length: 5(Max)mm
• Case Height: 1.5(Max)mm
• Screening Level: Automotive
• Product: Half-Bridge Drivers
• Rise Time: 22 ns
• Fall Time: 17 ns
• Propagation Delay Time: 25 ns
• Supply Voltage (max): 18 V
• Supply Voltage (min): 4.5 V
• Supply Current: 1.2 mA
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Bridge Type: Half Bridge
• Minimum Operating Temperature: - 40 C
• Output Current: 2.4 A
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• High Side Voltage - Max (bootstrap): -
• Lead Free Status / Rohs Status: Compliant
• Other names: FAN3268TMXTR

© 2009 Fairchild Semiconductor Corporation
FAN3268 • Rev. 1.0.1
Thermal Guidelines
Gate drivers used to switch MOSFETs and IGBTs at
high frequencies can dissipate significant amounts of
power. It is important to determine the driver power
dissipation and the resulting junction temperature in the
application to ensure that the part is operating within
acceptable temperature limits.
The total power dissipation in a gate driver is the sum of
two components, P
Once the power dissipated in the driver is determined,
the driver junction rise with respect to circuit board can
be evaluated using the following thermal equation,
assuming 
design (heat sinking and air flow):
P
Gate Driving Loss: The most significant power loss
results from supplying gate current (charge per unit
time) to switch the load MOSFET on and off at the
switching frequency. The power dissipation that
results from driving a MOSFET at a specified gate-
source voltage, V
switching frequency, f
P
where n is the number of driver channels in use
(1 or 2).
Dynamic Pre-drive / Shoot-through Current: A
power
consumption under dynamic operating conditions,
including pin pull-up / pull-down resistors, can be
obtained using the “I
graphs in Typical Performance Characteristics to
determine the current I
under actual operating conditions:
P
T
where:
T

T
J
J
B
TOTAL
GATE
DYNAMIC
JB
=P
=driver junction temperature
=(psi) thermal characterization parameter relating
=board temperature in location defined in
=Q
=P
temperature rise to total power dissipation
Note 1 under Thermal Resistance table.
TOTAL
JB
=I
G
loss
GATE
DYNAMIC
• V
was determined for a similar thermal
• 
GS
+ P
GATE
resulting
JB
• f
DYNAMIC
• V
+ T
SW
and P
GS
DD
• n
SW
B
, with gate charge, Q
DD
• n
, is determined by:
DYNAMIC
(No-Load) vs. Frequency”
DYNAMIC
from
:
drawn from V
internal
current
G
(1)
(2)
(3)
(4)
, at
DD
13
As an example of a power dissipation calculation,
consider an application driving two MOSFETs with a
gate charge of 60nC with V
frequency of 500kHz, the total power dissipation is:
The
characterization parameter of 
application, the localized temperature around the device
is a function of the layout and construction of the PCB
along with airflow across the surfaces. To ensure
reliable operation, the maximum junction temperature of
the device must be prevented from exceeding the
maximum rating of 150°C; with 80% derating, T
be limited to 120°C. Rearranging Equation 4 determines
the board temperature required to maintain the junction
temperature below 120°C:
P
P
P
T
T
GATE
DYNAMIC
TOTAL
B
B
=T
=120°C – 0.46W • 43°C/W=100°C
SOIC-8
J
=60nC • 7V • 500kHz • 2=0.42W
=0.46W
- P
=3mA • 7V • 2=0.042W
TOTAL
has
• 
JB
a
junction-to-board
GS
=V
JB
DD
=43°C/W. In a system
=7V. At a switching
www.fairchildsemi.com
thermal
J
would
(5)
(6)
(7)
(8)
(9)