TLE6281G_07 INFINEON [Infineon Technologies AG], TLE6281G_07 Datasheet - Page 10

• Manufacturer Part Number: TLE6281G_07
• Description: H-Bridge Driver IC Adjustable dead time with shoot through protection
• Manufacturer: INFINEON [Infineon Technologies AG]

tors. This means, that the bootstrap capacitor needs a minimum charging time of about 1µs,
if the highside switch is operated in PWM mode (e.g. with 20kHz a maximum duty cycle of
96% can be reached). The exact value for the upper limit is given by the RC time formed by
the impedance of the internal bootstrap diode and the capacitor formed by the external Mos-
fet (C
MOSFET the driver IC has to drive. Usually the bootstrap capacitor is about 10-20 times big-
ger than C
The charge pump is active when the highside switch is “ON” and the voltage level at the SHx
is higher than 4V. Only under these conditions the bootstrap capacitor is charged by the
charge pump.
Estimation of power loss within the Driver IC
The power loss within the Driver IC is strongly dependent on the use of the driver and the
external components. Nevertheless a rough estimation of the worst case power loss is pos-
sible.
Worst case calculation is:
P
With:
P
f
Q
n
const = Constant considering some leakage current in the driver (about 1.2)
I
V
P
This value can be reduced dramatically by usage of external gate resistors.
Conditions :
Data Sheet
PWM
VS(open)
Loss
Loss
VS
RGate
gate
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
= (Q
Mosfet
0
Estimated Power Loss P
= Power loss within the Driver IC
= Switching freqency
= Total gate charge of used MOSFETs at 10V V
= Number of switched MOSFETs
= Voltage at Vs
= Power dissipation in the external gate resistors
Junction temperature T
Number of switched MOSFET n = 2
Power dissipation in the external gate resistors P
0
= Current consumption of driver without connected Mosfets during switching
gate
=Q
Mosfet
10
for different supply voltages V
*n*const* f
Gate
at Q
Vs = 8V
Vs = 14V
Vs = 18V
PWM Frequency (kHz)
. External components at the Vs Pin have to be considered, too.
G
20
= 100nC @ V
/ V
GS
30
LOSS
). The size of the bootstrap capacitor has to be adapted to the external
PWM
within the Driver IC
GS
40
= 10V
+ I
50
j
VS(open)
s
= 25
60
o
C
)* V
Vs
- P
10
RGate
GS
RGate
0,8
0,7
0,6
0,5
0,4
0,3
0,2
0,1
0
0
= 0,2*P
Estimated Power Loss P
Data Sheet TLE 6281G
10
Loss
for different gate charges Q
PWM Frequency (kHz)
at supply voltage V
Q
Q
Q
20
G
G
G
= 50nC
= 100nC
= 200nC
Rev 2.3 2007-01-11
30
LOSS
within the Driver IC
40
s
= 14V
50
G
60