TRANSITION-MODE SINGLE STAGE PFC LED POWER
The iP7302 operates on fly-back circuit after
rectifier diode, so the waveform of input current
follows that of input voltage. It is a peak current
mode fly-back PFC controller, with valley turn-on
/Quasi Resonant mode (QR), so very high
efficiency is easily achieved.
iP7302 is different from iP7300 in the connections
of inputs of error amplifier between pin1 and pin2.
The Pin1 is connected to positive input and pull up
50KΩ resistor to internal supply of 5V. The
negative input is connected to output to form unity
gain buffer. Pin2 is non connected. This
modification is specially made to suit single stage
LED power supply which requires PFC.
The structure of single stage LED power supply
with PFC offers several advantages: high PF, no
need of bulk electrolytic capacitor, output isolates
from line input, reasonable size and cost. The
disadvantage is that the output contains
120/100Hz ripple. But with iP7700, the average
current may be controlled very well.
With output clamp at 18V, the iP7302 has a wide
VDD operation range. The turn-on delay of soft-
drive facilitates valley voltage switching, and the
soft drive itself minimizes turn-on current spike.
Thus higher efficiency could be achieved.
The iP7302 is packaged with small size SOP-8,
and it is easy to use with few external components.
It is also equipped with under voltage lock out
( UVLO ) with very small start-up current.
Wide VDD operation range with internal
output voltage clamp at 18V
UVLO with low standby current
Soft drive for minimizing turn-on current
Zero current with valley voltage switching
Low operating current
SOP-8L packaging with few external
High power factor with low THD
4. Pin Assignments