White LED Set-up Converter

EC4501

Page 8 of 10

3F27N-Rev.P001

Function Description

Driving Capability

Inductor Selections

Capacitor Selection

The small size of ceramic capacitors makes them ideal for

EC4501 applications. X5R and X7R types are recommended

because they retain their capacitance over wider voltage

and temperature ranges than other types such as Y5V or

Z5U. A 1μF input capacitor and a 0.22 μF output capacitor

are sufficient for most EC4501 applications.

Diodes Selection

Schottky diodes, with their low forward voltage drop and

fast reverse recovery, are the ideal choices for EC4501

applications. The forward voltage drop of a Schottky diode

represents the conduction losses in the diode, while the

For diode selection, both forward voltage drop and diode

capacitance need to be considered. Schottky diodes with

higher current ratings usually have lower forward voltage

drop and larger diode capacitance, which can cause

significant switching losses at the 1.25MHz switching

frequency of the EC4501. A Schottky diode rated at 100mA to

200mA is sufficient for most EC4501 applications. Some

recommended Schottky diodes are listed in the following

table:

L

LED Current Control

The LED current is controlled by the feedback resistor. The

feedback reference is 104mV. The LED current is 104mV/Rfb.

In order to have accurate LED current, precision resistors are

preferred (1% is recommended). The formula and table for

RFB selection are shown below

Open Circuit Protection

Open circuit protection will shut off the EC4501 if the output

voltage goes too high when the OV pin is tied to the output.

In some cases an LED may fail, which will result in the

feedback voltage always being zero. The EC4501 will then

switch at its maximum duty cycle boosting the output voltage

higher and higher. By connecting the OV pin to the top of the

LED string the EC4501 checks this condition and if the output

ever exceeds 20V, the EC4501 will shut down. The part will

not switch again until the power is recycled.

PARTNUMBER

DCR

（

Ω）

CURRENT RATING

（mA）

MANUFACTURER

LQH3C220

0.71

250

MURATA

CDRH3D16

‐220

0.53

350

SUMIDA

LB2012B220M

1.7

75

TAIYO YUDEN

LEM2520

‐220

5.5

125

TAIYO YUDEN

EJPC220KF

4.0

160

PANASONIC

5

20.8

10

10.4

15

6.93

20

5.1

PART

NUMBER

FORWARD

CURRENT

（mA）

VOLTAGE DROP

（V）

DIODE

CAPACITAN

CE

MANUFACTURER

CMDSH

‐3

100

0.58@100mA

7.0@10V

Central

CMDSH2

‐3

200

0.49@200mA

15@10v

Central

BAT54

200

0.53@100mA

10@25v

Zetex