l293d interface MCU to relay

[mshh]

relays are working on 5 v, so does the l293d.
if the supply vcc is 5 v , what is the expected output to the relay? will it be able to drive the relay or should i raise the vcc voltage of l293d ?

 

[KlausST]

Hi,

The correct way to do this:
* open the relay datasheet and look for the min pickup voltage
(This is the voltage where you can be sure the relay gets activated)
* find the according relay current

Now open the power supply datasheet
* and find the minimum expectable output voltage

Now open the L293D datasheet
* and find the expectable output voltage @ minimum supply voltage and min relay pickup current

If this output voltage is higher than the relay pickup voltage, then you are safe.
(Ignoring all wire resistance and other voltage drops)

Klaus