ICE2QS03G_16 Datasheet, PDF (9/28 Pages) Infineon Technologies AG – 45 W adapter demo board

45 W adapter demo board
Using the new 800 V CoolMOS™ P7 and ICE2QS03G quasi-resonant PWM controller
Design considerations
5
Design considerations
5.1
800 V MOSFET
The 800 V P7 CoolMOS™ provides several benefits for charger and adapter applications. An 800 V breakdown
voltage allows a higher combination of bus voltage, reflected voltage, and snubber voltage than can be achieved
with a 600 V or 650 V device. By allowing a higher reflected voltage and snubber voltage the system power losses
can be reduced while maintaining higher breakdown voltage margins.
Figure 11 MOSFET V_DS during turn off in the Infineon 45 W adapter
In this specific design the reflected voltage was increased from the Infineon 35 W adaptor which used a 600 V
device. This section will compare the Infineon 35 W adapter design using a 600 V MOSFET with the Infineon 45 W
adapter using an 800 V MOSFET to show the difference in performance between the two designs.
The reflected voltage determines the trough (valley) voltage during DCM ringing where the switch turns on in the
QR flyback converter. By allowing a higher reflected voltage there is a resulting lower trough in the ringing
waveform. This allows the converter to switch at a lower V_DS voltage and reduce the system's switching losses
especially at high line (265 V_AC) operation.
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Table 4
Parameter
Transformer primary turns
Transformer secondary turns
Output voltage
Diode forward voltage
Transformer reflected voltage
Application Note
Symbol
N_P
N_S
V_output
V_forward
V_reflected
600 V design
66 turns
11 turns
19 V
0.55 V
117 V
9
800 V P7 design
87 turns
8 turns
19 V
0.4 V
211 V
Revision 1.0
2016-06-27