IXTP70N075T2 데이터 시트보기 (PDF) - IXYS CORPORATION
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IXTP70N075T2 Datasheet PDF : 11 Pages
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DC to DC Synchronous Converter Design
Abdus Sattar, IXYS Corporation
IXAN0068
We can write as:
PBD = Ptd1 + Ptd 2
(12)
Where Ptd1 is the body diode loss during dead time td1 and Ptd2 is the body diode loss
during dead time td2.
Ptd1
=
Pcd1
+ Prr1
=Vf
•
⎜⎛
⎝
I
O
−
ΔI L
2
⎟⎞ • td1•
⎠
fS
+
1
2
•
Vin
• I rr
• trr
•
fS
(13)
Ptd 2
=
( Pcd 2 Prr 2
=
0) = Vf
•
⎜⎛
⎝
I
O
+
ΔI L
2
⎟⎞ • td 2 •
⎠
fS
(14)
PWM Gate Driver Power loss: [1]
The power dissipation in the driver is defined by,
PDRIVER = QG(onl) • VDD • f S
(15)
where Qg(onl) is the total gate charge of the MOSFET and VDD is the driver power supply.
The gate “point of voltage” is,
VSP
= VTH
+
IO
g fs
The driver current is,
I = R V − V + R DRIVER(L−H )
DD
SP
DRIVER( PULL−UP )
Gate
I = R V − V + R DRIVER(H −L)
DD
SP
DRIVER( PULL−DOWN )
Gate
(16)
(17)
(18)
The rise time is,
t = I Q t(on)
G ( on )
DRIVER( L−H )
The fall time is,
t = I Q t(off )
G (on)
DRIVER( H −L)
(19)
(20)
If an external Schottky diode (D1) is used across Q2, the Schottky’s capacitance needs to
be charged during Q1 turn-on. The power loss to charge the Schottky’s capacitance is,
PC (SCHOTTKY )
=
CSCHOTTKY • VIN2
2
•
fS
(21)
6
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