IXTA200N055T2 Ver la hoja de datos (PDF) - IXYS CORPORATION
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IXTA200N055T2 Datasheet PDF : 11 Pages
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DC to DC Synchronous Converter Design
Abdus Sattar, IXYS Corporation
IXAN0068
The power dissipation in the driver is defined by,
PDRIVER
= TJ − Ta
RthJC
= QG(total) • VDD •
f SW
where VDD = 10V and fS = 200 kHz (assume for this case)
The estimated driver power dissipation, PD ≈ 42 •10−9 •10 • 200 •103 = 84mW
Dead-Time Power Loss: [3]
The dead-time is defined as the time required when both the MOSFETs are off in order to
prevent shoot-through. In this period, the Schottky diode (or integral body diode is
forward-biased and provided a power loss defined by,
Driver IXS839 provides delay time in the datasheet,
tDelay _ Time (nS ) = CDelay ( pF ) • (0.5nS / pF )
(22)
Assume, td1 = td 2 = 100nS , which provides CDelay ( pF ) = 200 pF
The Delay-Time loss is define in (11-13) as
Ptd1
=
Pcd1 + Prr1
=Vf
•
⎜⎛
⎝
I
O
−
ΔI L
2
⎟⎞ • td1•
⎠
fS
+
1
2
•
Vin
• I rr
• trr
•
fS
= 0.85 • ⎜⎛12 − 0.528 ⎟⎞ •100x10−9 • 200x103 + 1 •12 • 2.2 • 37x10−9 • 200x103
⎝
2⎠
2
= 0.19905+0.09768= 0.297W= 297mW
Ptd 2
=
( Pcd 2 Prr 2
=
0) = Vf
•
⎜⎛
⎝
I
O
+
ΔI L
2
⎟⎞ • td 2 •
⎠
fS
= 0.85 • ⎜⎛12 + 0.528 ⎟⎞ •100x10−9 • 200x103 =0.208W= 208mW
⎝
2⎠
PBD = Ptd1 + Ptd 2 = 297mW + 208mW = 505mW
Synchronous Converter Efficiency:
If we neglect inductor’s DC power loss and capacitor’s ESR loss then the total
estimated power loss, Ploss= 1337mW+1007mW+84mW+505mW=2933mW= 2.933W
Given output power, Po = Vo*Io = 3.3*12= 39.6W
Estimated input power, Pin= 39.6+2.933=42.6W
The efficiency is defined as, η = VoIo = Po
(23)
Vin • Iin Pin
10
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