DM114

點晶科技股份有限公司

SILICON TOUCH TECHNOLOGY INC.

8-BIT CONSTANT CURRENT LED DRIVERS with 3.3V~5V supply voltage

Version:A.007

Page 12

System Configuration Example

Sink current is set by the external resistor as shown in figure (Iout vs. Rext).

= V

To prevent too much power dissipated by the device due to higher V

be used to reduce the Vout when the outputs consume current:

R =

(max)

(max)

(min)

Bit

I

V

V

V

O

O

f

LED

•

−

−

Note

This device has only one ground pin shared by signal, output sink current, and power ground.

It is advisable to pattern the ground layout with minimized inductance such that the switching

noise induced by the input signals and the output sink current would not cause chip malfunction. To

prevent the drivers’ outputs from damage by overshoot stress, it is also advisable not to turn off the

drivers and scan transistors simultaneously.

SER I A L -O U T

R

OU T 7

OU T 0

GN D

R-E X T

LA T C H

CP U

SER I A L -IN

EN ABL E

SC AN

CL O C K

SER I A L -O U T

OU T 7

OU T 0

GN D

R-E X T

LA T C H

SER I A L -IN

EN ABL E

CL O C K

Vo