ULN2804A SOC18

[Franco1]

Hi, I can't find the ULN2804A with SMD SOC18 surface assembly, my question is,
can I replace with the unl2803a SMD SOC18 ?

n practice I have to repair an electronic card,
I found all the components excluded the ULN2804A with surface assembly Soc18,
which I have not found in TME, RS, Mouser, Farnell and in Google, all have the Dip18,
looking at the Datasheet I noticed the UlN2803A SOC18 , who is almost the same,
then I tried to ask if I was the suppliers I know,
nobody gave me a positive answer and they suggested to me to ask you,
thanks for your attention

[Peter BENSCH]

Welcome @franco, to the community!

The ULN2804A from STMicroelectronics is only available in PDIP18. An alternative could be the ULQ2004 with generally identical parameters, but only seven transistors instead of eight at the ULN2804A. There is still the ULQ2804 with 8 transistors, but also only in PDIP18.

The ULN2803A has a different internal base resistor, so you cannot use it without changing the environmental circuit (by adding a 7.8kohms resistor in series to each input). However, this also changes the input behaviour, as the internal protective diode is then connected via the resistor. So it depends on the circuit and the task of the circuit whether you can do this.

Hope that helps?

Regards
/Peter

[Franco1]

si ho visto questo che mi dici nello schema , è difficile aggiungere le resistenze

yes I saw what you tell me in the scheme, it is difficult to add the resistance