Multiplex vs Duty Cycle

S

Suraj143

Active Member

• Nov 11, 2010

• #1

I’m multiplexing 4 seven segments. Each seven segment needs 100mA current.

In this case the duty cycle will be 25% per segment. Means its getting only 25mA current per segment when multiplexing.

From my hardware I pump current 4times (4 X 25 = 100mA) to a segment, now what will my duty cycle value does it still 25%??

 

Last edited: Nov 11, 2010

blueroomelectronics

Well-Known Member

• Nov 11, 2010

• #2

You'll need 400mA to get 100mA per segment at 1/4 duty. Make sure your LEDs can handle that.

 

S

Suraj143

Active Member

• Nov 11, 2010

• #3

That means if I pump 4 X 25mA = 100mA still the duty cycle is 25%??

 

S

Suraj143

Active Member

• Nov 11, 2010

• #4

Ok for easy understand see this example.

An LED needs 20mA current to its maximum brightness.Now I light up this LED 1/4th duty cycle.So now the LED will light up 25% of its brightness.

Now I pump 80mA & do a 1/4th multiplex.Now is still the duty cycle 25%? what about the brightness??

 

Last edited: Nov 11, 2010

P

Pommie

Well-Known Member

Most Helpful Member

• Nov 12, 2010

• #5

The duty cycle will still be 25% but the brightness will be 100%.

Mike.

 

S

Suraj143

Active Member

• Nov 12, 2010

• #6

Pommie said:

The duty cycle will still be 25% but the brightness will be 100%.

Mike.

Click to expand...

Totally understood Mike that's what I want to know.

Thanks