Datasheet

n Lp
toff Ipk
Vo Vf
·
= ·
+
Lp
ton Ipk
Vin
= ·
Vin di
Lp dt
=
t
on
t
off
T
p
Ns
Naux
VoutVaux x
The peak Primary Current
The Auxillary
Winding voltage
Np
Naux
VinVaux x
td
The peak Secondary Current
0V
0.35V
T
OVP
LM5023
www.ti.com SNVS961D –APRIL 2013–REVISED JANUARY 2014
Figure 11. QR Converter Typical Waveforms
Quasi Resonant Operating Frequency
When the primary side Flyback MOSFET turns on, the current ramps up until the peak primary current exceeds
the feedback compensation error voltage. When this occurs the PWM comparator resets the output drive, turning
off the MOSFET. The current ramps up with a slope of:
The t
ON
time of the switch is calculated by:
When the primary side Flyback MOSFET is turned off, the energy stored in the primary inductance is transfer to
the secondary inductance, the off time to transfer all of the energy is:
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