點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

DD331

High CONSTANT CURRENT LED DRIVERS

Version:A.002

Page

7

Typical Application

DD331

Application Notice

Notice the Rext applies to lower than 5 Ω, the wire resistance(Rwire) will affect Iout a

lot. For example, when Rext=5Ω Iout= 104mA, if Rwire=1Ω, than Iout will decrease

1.96%. Due to large current flow through rext, it needs high power resistor to apply to

prevent element burn out issue.

Dissipation Ratings

PACKAGE

POWER DISSAPATION

( Tj_max=150

THERMAL RESISTANCE

SOP16

1.7 W

SSOP16

1.5 W

Power Dissipation

Notice that the power dissipation of a semiconductor chip is limited to its package and

ambient temperature, in which the device requires the maximum output current calculated

for given operating conditions. The maximum allowable power consumption can be

calculated by the following equation:

Tj(junction temperature)(max)( C) - Ta(ambient temperature)( C)

Pd(max)(Watt) =

Rth(junction- to- air thermal resistance)( C/Watt)

°°

°