Velleman DCA55 - Manual (Page 10)

Atlas DCA User Guide October 2007 – Rev 7
Page 10
Bicolour LEDs
Bicolour LEDs are automatically identified. If your LED has 3
leads then ensure they are all connected, in any order.
A two terminal bicolour LED consists of two LED chips which
are connected in inverse parallel within the LED body. Three terminal bicolour
LEDs are made with either common anodes or common cathodes.
Here a two terminal LED
has been detected.
This message will be
displayed if the unit has
detected a three terminal
LED.
The details of each LED in the package
will then be displayed in a similar way
to the diode networks detailed earlier.
The pinout for the 1
st
LED is displayed.
Remember that this is the pinout for just
one of the two LEDs in the package.
Interestingly, the voltage drops for each
LED relate to the different colours
within the bicolour LED. It may
therefore be possible to determine which
lead is connected to each colour LED
within the device. Red LEDs often have
the lowest forward voltage drop,
followed by yellow LEDs, green LEDs
and finally, blue LEDs.
Two terminal
bicolour LED
Three terminal
bicolour LED
Pinout for D1...
RED GREEN BLUE
Anod Cath
Forward voltage
D1 Vf=1.98V
Test current
D1 If=3.22mA