l293d interface MCU to relay

Thread Starter

mah

Joined Mar 15, 2010
393
could i use l293d to interface MCU to separate relays?
do i need external freewheeling diodes ?
is there any problem with this circuit
 

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sghioto

Joined Dec 31, 2017
2,336
Circuit looks OK to me. One issue might be the Vcc2 supply. The high level output from the L293 will be less then the supply voltage so might be a problem with the relays.
If necessary you could raise the Vcc supply a bit to compensate.
SG
 

Thread Starter

mah

Joined Mar 15, 2010
393
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?
 
Last edited:

MisterBill2

Joined Jan 23, 2018
8,505
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?
The relay voltage depends on the relay current, and if the relays draw 50 mA then the voltage should be at least 4.8 volts. Since the usual tolerance on relay voltages is 10%, it should work out very well.
 
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