IN-PLUG

© Copyright 2005-2007 - ASIC Advantage, Inc. – All rights reserved

- Revision 11 – April 02, 2007

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Fig. 10

DIMMING OPTIONS:

This section describes the dimming options and the components included in the associated ‘Dimming” block as

shown in Fig. 11.

Linear dimming

A DC power supply connected through a 1N4148 diode and 100k resistor to the LEDSNS input (pin 5) and ramped

from 0 to 10 volts will provide a fairly good dimming function. There is no effect until the voltage is above 0.50 volts,

but it is gradual after that. An improvement would be to add a buffer operational amplifier with an offset, running off

VCC. This would allow for a 0 to 5 volt linear control with low offset. The series resistor value needs to be chosen with

more scrutiny to get full utilization of the voltage control range.

PWM dimming

Changing the resistor to 24k ohms allows for fairly good PWM input control. The resistor is smaller since the PWM

only goes to 5V. Tuning the series resistor value here would also be necessary for full range control.

Typical dimming frequency range 50Hz – 500Hz

Fig. 11

R10

100k

D27

1N4148

Linear dimming

to LEDSNS

Input

R10

24k

D27

1N4148

PWM dimming

to LEDSNS

Input