2ED100E12-F2_EVAL Infineon Technologies, 2ED100E12-F2_EVAL Datasheet - Page 11

• Manufacturer Part Number: 2ED100E12-F2_EVAL
• Description: Power Management IC Development Tools Eval Driver Board EconoDual
• Manufacturer: Infineon Technologies

3.3
The IGBT switching frequency is limited by the available power and by PCB temperature. According to
theory the power losses generated in gate resistors are a function of gate charge, voltage step at the driver
output and switching frequency. The energy is dissipated mainly through the PCB and raises the
temperature around the gate resistors. When the available power of the DC/DC converter is not exceeded,
the limiting factor for the switching frequency is the absolute maximum temperature for the FR4 material. The
allowed operation temperature is 105 °C.
Generally the power losses generated in the gate resistors can be calculated according to formula (1):
In this formula
value can be approximately calculated from the datasheet value by multiplying by 0.8.
Most of the losses are shared between the internal –
Negligible losses are also in the driver IC itself. Due to the PCB temperature criteria the power dissipated in
external gate resistors
takeing relevant thermal resistances of this part of the board into account.
Based on experimentally determined board temperatures the following thermal resistances have been
calculated using an equivalent circuit diagram as given in Figure 7:
Gate resistors to baseplate:
Gate resistors to ambient:
Figure 7
Application Note
P
dis
PCB
is the dissipated power,
T
T
T
BASE
G
A
Maximum switching frequency
Thermal equivalent circuit
f
R
R
s
resembles the switching frequency,
thR-A
thB-G
AIR
IGBT
P
Rgext
P
R
gext
Q
is to be considerd for the thermal design. Temperatures can be calculated
R
R
ge
R
thB-G
thR-A
thB
is the IGBT gate charge value corresponding to -8/+16V operation. This
R
thR
G
P
= 45 K/W
= 39 K/W
( *
dis
A
Driver board for EconoDUAL™3 and EconoPACK™+
T
BASE
R
P
thB
Rgext
G
T
A
)
11
V
P
out
Rg
P
represents the voltage step at the driver output
int
Rg
int
and the external –
V
out
f
s
R
R
thR-A
Q
thB-G
ge
P
Rgext
Application Note
gate resistors.
V1.2, 2009-08
AN2008-02
P
Rgext
(1)