MP4088GS datasheet(15/20 Pages) MPS

15 / 20 page

MP4088 – NON

MP4088 Rev. 1.0

11/23/2015

MPS Proprietary Information

APPLICATION INFORMATI

Selecting the Inductor

The MP4088 has a minimum off-tim

inductor current ripple at CCM is de

the inductor value and the minim

limit. The current ripple is limited

achieve a tradeoff between the p

and the dimming performance. The

value can be calculated with Equatio

OUT

OFF _ MIN

PEAK

0.8 I

If the inductance value is too larg

switching frequency is low and

performance is good. However,

dimming performance is poor in this

the inductance value is too small,

dimming performance is good, but

may work in an open-loop condition

current consistency poor. Therefore

must be made.

Freewheeling Diode

The diode should have a maximu

voltage rating greater than the max

voltage. The current rating of th

determined by the output current, w

be larger than 1.5 to 2 times the outp

Slow diodes cause excessive and

leading edge current spikes during

long reverse-recovery time of the f

diode can affect efficiency and circu

as well. An ultrafast diode (trr < 75n

WUGC10JH or ES1G, is recommen

Over-Voltage Protection (OVP) Po

A feedback resistor is used to dete

voltage

condition.

Figure

connection of the feedback resistor.

The

MP4088

employs

protection (OVP). When OVP is tr

maximum output voltage can be cal

Equation (5):

OUT _ OVP

OVP

R2 R3

=⋅

−

Where VD is the freewheeling dio

voltage drop.

N-ISOLATED, TRIAC DIMMABLE PFC LED DR

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n. Patent Protected. Unauthorized Photocopy and Duplication Pro

ION

me limit. The

etermined by

mum off-time

to 80% to

power factor

e inductance

on (4):

(4)

ge, then the

d the EMI

the TRIAC

condition. If

the TRIAC

the system

, making the

e, a tradeoff

um reverse-

ximum input

he diode is

which should

put current.

d unwanted

g start-up. A

freewheeling

uit operation

ns), such as

ded.

oint Set

ect an over-

shows

the

over-voltage

iggered, the

lculated with

−

(5)

ode forward

Figure 7: Feedback Res

The upper feedback resis

larger than 100kΩ to a

reduction in the applicatio

type is recommended to

protection.

Dummy Load

The dummy load is used to

transferred to the output c

occurs. The IC works in h

any power consumption.

Normally, a dummy load

recommended. This does

system efficiency but can

over-voltage protection.

Surge

Place an appropriate RCD

diode

rectifier

bridge

performance.

For

most

1µF/400V electrolytic capa

diode is recommended. Th

large as 1MΩ to reduce

normal operation.

RIVER FOR 230VAC

ohibited.

istor Connection

stor (R3) should be

avoid an efficiency

on. A 1% tolerance

o achieve accurate

o consume the power

capacitor when OVP

hiccup mode without

less than 1mA is

not deteriorate the

n guarantee normal

snubber beside the

for

optimal

surge

applications,

acitor with a 1000V

e resistor can be as

power loss during

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