ULN2003 RGB leds with common catode

Other Hardware 3rd Party Boards
1

Hi people.
I have a problem in driving RGB LEDs with ULN2003.
The ULN2003 gives a negative value as an output. And therefore I cannot pilot the colors but only the lighting of the entire LED.

I ask if something can be done and if you could tell me about alternative ULN2003 microcontrollers accessible at cost.

Ciao persone.
Avrei un problema nel pilotare dei led RGB con l'ULN2003.
L'ULN2003 da come uscita un valore negativo. E perciò non posso pilotare i colori ma solo l'accensione dell'intero led.

Chiedo se è possibile fare qualcosa e sennò se mi potreste dire dei microcontrollori alternativi all'ULN2003 accessibili a livello di costo.

2

Ciao Nick005,
Benvenuto nel forum. C'è una sezione italiana che potresti usare, se vuoi che il tuo post sia trasferito lì, ti preghiamo di segnalarlo al moderatore e chiedere loro di spostarlo. Se sei felice di ricevere risposte in inglese, lascia qui.
Grazie.

Hi people.
I have a problem in driving RGB LEDs with ULN2003.
The ULN2003 gives a negative value as an output. And therefore I cannot pilot the colors but only the lighting of the entire LED.

I ask if something can be done and if you could tell me about alternative ULN2003 microcontrollers accessible at cost.

3

Language changed.
I know how to speak in English. Or.. at the minimum i know how to read it and translate.

4

TBD62783 is DMOS high-side version of 2803.
TBD62083 is the DMOS version of 2803, and TBD62003 is the DMOS version of the 2003

The DMOS versions use MOSFETs instead of BJTs internally, so they are much better switches (as you may have noticed, the 2803 doesn't drive the output all the way to gnd).

There was a high-side version of the 2803, made using PNP BJTs (UDN2981), but it appears to be considered obsolete, and out of production (the 2803/2003 is only still in production owing to the massive number of circuits and equipment that use it, despite it being every bit as obsolete as the high side version, and really crappy compared to modern MOSFETs).

Also, you generally want to buy common anode LEDs, not common cathode - for a given price, low side switches are always better (fabrication is easier for a given level of performance), and have fewer complications in using them (though the TBD62783 doesn't have such complications). Which is why the ULN2xx3 series is still used all over the place, while the high-side version was unpopular and out of production.