FA5550 Fuji Electric holdings CO.,Ltd, FA5550 Datasheet - Page 11

• Manufacturer Part Number: FA5550
• Description: Power Factor Correction Converter
• Manufacturer: Fuji Electric holdings CO.,Ltd

(3) No. 3 pin (MUL pin)
Function:
(a) Input of input voltage waveform (sine-wave)
(b) Detection of brownout
How to use:
(a) Input of input voltage waveform (sine-wave).
・ How to connect:
・ Operation
(b) Brownout
・ How to connect:
・ Operation
(4) No.4 pin (IS pin)
Function:
(a) Detection of MOSFET current value
How to use:
(a) Detection of MOSFET current value
・ How to connect:
・ Operation
・ Supplementary explanations
Rev.1 Feb-2008
surge current due to discharge from parasitic capacities in
thecircuit may run through the current detection resistor Rs. The
large surge current may result in malfunction and distortion of
the input current waveform. CR filters are usually connected as
the measure.
Input rectified voltage of AC input with its voltage in
resistance-divided. In addition, connect C between MUL and
GND.
The rectified voltage input to MUL pin and ERRAMP output are
inputted into the multiplier (MUL), and a near-sinusoidal wave is
outputted from the multiplier. The output of the multiplier is set
as a reference of the comparator, and the comparator controls
the input voltage in the form of sine waves. In addition, because
the rectified voltage of AC input contains much noise
components due to the switching of Q1, a capacitor is normally
connected as a filter.
Brownout function stops the output pulses when AC input
voltage drops below programmed voltage. (See page 14)
Connect a current detecting resistor Rs between the source pin
of MOSFET and GND, and input the current signal of MOSFET
generated with this resistor.
When output voltage of the multiplier and voltage of IS pin are
inputted into the comparator and IS pin voltage becomes larger
than the output of the multiplier, the comparator turns over its
output signal to turn OFF the OUT output.
The overcurrent limiting function limits the maximum threshold
voltage of IS pin within 1V.
When MOSFET turns on, gate driving current of MOSFET and
The same method as the control of the input current in the form
of the sine-wave
FA5550 / 51
11
Fuji Electric Device Technology
IS
IS
4
Fig.8 MUL pin circuit
4
Fig.9 IS pin circuit
Fig.10 Filters of IS pin
MUL
3
MUL
ERRAMP
CUR.comp