WS3620 datasheet(4/7 Pages) WINSEMI

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WS3620 Product Description

WIN SEM I

M ICROELECTRON ICS

WIN SEM I

M ICROELECTRON ICS

WIN SEM I

M ICROELECTRON ICS

WIN SEM I

M ICROELECTRON ICS

WIN SEM I

M ICROELECTRON ICS

Function

Function Description

Description

Output

Output Current

Current

Current Setting

Setting

Output current can be set by Rext Resistor, the formula is:

Iout

REXT

Efficiency

Efficiency Design

Design

Below shows the application circuit efficiency formula：

LED

Vin is system input power voltage. VLED is single LED drop

voltage. ILED is LED current. It is can be seen thatlarger

quantities of series LED in system brings higher efficiency.

In system design,WS3620 output operating voltage is based

on application environment so that it optimizes N value.

LED

LED Series

Series

Series Number

Number

Number Design

Design

Designing LED series number in the system should consider

two aspects below:

output voltage is VOUT = Vin – n*VLED.

(1) To ensure the normal operation, output voltage should

be VOUT > VOUT_MIN；

(2) Lower output voltage brings higher system efficiency.

Basing on the two points above, WS3620 output voltage

range is VOUT_MIN ~ VOUT_MAX and LED series number

formula is:

LED

MIN

OUT

LED

MAX

OUT

Vin

−

Input

Input Capacitor

Capacitor

The larger capacitance C2 produces smaller voltage ripple

to Vin, and keeps small ripple to SM2082 output

voltage. C2 capacitance depends on total operating current

from LED tubes: the more current generates the

more C2 capacitance (usually 4.7uF/400V~22uF/400V). The

formula is shown below:

LED

∆

ILED is output current, time t = 1/4/Fac=5mS, △V is output

voltage ripple。

Increase

Increase Output

Output

Output Power

Power

The quantity of chip is based on the amount of parallel

connection groups and lights operating current of LED tubes.

In the diagram below, resistor of REXT1~REXT2 can be the

same or different.

In IC parallel application, when Rext value is different, the

constant current turn-on voltage in the system is the

maximum voltage of parallel WS3620.

2 2 0 V ~

L E D 1 -1

L E D 1 -n

L E D 2 -1

L E D 2 -n

C 2

R e x t 1

R e x t 2

R e x t N

C 3

G N D

O U T

G N D

R E X T

I C 1

O U T

G N D

R E X T

O U T

G N D

R E X T

I C 2

I C N

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