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Design Information
(9)
The parallel sense resistor combination (R30||R31) has to dissipate the maximum power:
(10)
Switching Diode
The main switching diode (D10) should be sized to block the maximum reverse voltage , operate at the
maximum average current, and dissipate the maximum power:
(11)
Definitions
n – Primary to Secondary Turns Ratio
V
OUT
– Regulated Output Voltage
V
IN
– Nominal AC Input Voltage
V
IN-PK
– Peak Input Voltage
V
IN-PK-MAX
– Maximum Peak Input Voltage
I
P-PK
– Peak Primary Current
I
S-PK
– Peak Secondary Current
I
IN-PK
– Peak Input Current
I
LIM
– Peak Current Limit
D
MIN
– Minimum Duty Cycle over Line Cycle
V
R
– Output Voltage Reflected to Primary
V
R-MAX
– Maximum Tolerable Reflected Voltage
V
T-DES-MAX
– Maximum Tolerable MosFET Voltage
V
T-MAX
– Maximum MosFET Blocking Voltage
I
T-RMS-MAX
– Maximum MosFET RMS Current
I
T-PK-MAX
– Maximum MosFET Peak Current
P
T-MAX
– Maximum MosFET Power Dissipation
V
RD-MAX
– Maximum Diode Blocking Voltage
I
D-MAX
– Maximum Diode Average Current
I
D-PK-MAX
– Maximum Diode Peak Current
P
D-MAX
– Maximum Diode Power Dissipation
9.4
Transformer
Primary Inductance
11
SNVA485B – June 2011 – Revised May 2013
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