MP44011 – BOUNDARY-MODE PFC CONTROLLER WITH HARMONIC INJECTION

MP44011 Rev. 1.01

www.MonolithicPower.com

13

1/12/2012

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The turn ratio is:

R

OUT

V

n=

=3

V

P

PKp

RMSp

94

pe

w

max

c

LI

I

A =A A =

1.27 10 mm

BK j











Where:

design;

j is the current density of the wire, which is

The primary inductor turn number is:

pPKp

p

max

e

LI

N110

BA







The needed air gap is:

2

pe

4

P

NA

6.08 10 m

L



 







And the secondary winding turn number is:

p

s

N

N36

n



6. MOSFET

The maximum drain voltage is:

DSmax

PKmax

R

V=V

V

ΔV=685V



The maximum RMS MOSFET current is:

Qrms_max

RMSp

I

=I

And the pulse-drain current is:

Q_pulse

PKp

I>I

The FQPF8N80C (800V/8A) meets the power

requirement of the design.

7. Secondary Diode

The maximum RMS current of the output diode is:

Drms_max

RMSs

I

=I

=1.03A

And the maximum reverse voltage is:

PKmax

Dmax

OUT

V

V=

V

194V

n



UF3004 (400V/3A) meets the design criteria.

8. Output Capacitor

The output capacitor is selected only based on

output voltage ripple

OUT

V

OUT

3

LV

O

I

F4(K )

1

C=

K

38 F

2 π fF2(K ) ΔV











The cap (47μF/100V) is selected as the bus

capacitor.

9. Sense Resistor

on the multiplier input, the peak value at the

minimum

line

voltage

is

85/265=0.8V which is multiplied by the maximum

slope of the multiplier, 1.62, giving a 1.32V peak

on the current sense. So the sense resistor will

not exceed:

sen

PKp

1.32

R0.87

I





Considering the power consumption, select a

0.4Ω sense resistor.

The first stage of flyback PFC design is complete.

Our evaluation board adds two channels of

DC/DC using the MP4689 to constitute a system

for the LED driver. For MP4689 applications,

please find MP4689 datasheet for details.

Figure 8 shows the application schematic with

power stage design. The typical performance and

circuit waveforms are shown in the typical

performance characteristics section. For more

possible applications of this device, please refer

to related Evaluation Board Datasheets.