Can I leave Vref pin on L6203 unconnected ?

[alex]

Hello All,

Could somebody please comment on a purpose of Vref pin in L6203. The
datasheet recommends putting a bypass capacitor there, but does not say
what will happen if I do not.

All publicly available schematics I could find on the Internet seems to
follow the datasheet recommendation and put a capacitor. I wonder if it
is really necessary if I do not use that reference voltage at all?
Omitting the capacitors would simplify my layout, because I am doing a
single layer PCB.

Thanks ahead.

Kind Regards,
Alex

 

[Glen]

I would always connect Vref on any circuit that is using a voltage or
current feedback loop. According to the datasheet, Vref is an internal
voltage reference. How it's being used isn't apparent, but more than
likely it's used to control the op-amp(s) output based on your voltage
input. You'll have to forgive my rusty EE knowledge. I've been in the
IT world too long and out of the fun stuff.

Your best bet is to contact the manufacturer and get more details on
the chip and how the voltage reference is being used. You may be able
to get by with leaving the pin unconnected, but I wouldn't recommend
it. One thing you don't want to do is route it directly onto the
board's ground plane. Ground loops and noise will wreck havoc. Thus,
the capacitor is recommended if you are connecting it.

-Glen

 

[Anthony C Smith]

Hello All,

Could somebody please comment on a purpose of Vref pin in L6203. The
datasheet recommends putting a bypass capacitor there, but does not say
what will happen if I do not.

All publicly available schematics I could find on the Internet seems to
follow the datasheet recommendation and put a capacitor. I wonder if it
is really necessary if I do not use that reference voltage at all?
Omitting the capacitors would simplify my layout, because I am doing a
single layer PCB.

Thanks ahead.

Kind Regards,
Alex

The V ref pin sets the internal thresholds for the protection and input
levels- not connecting it will mean the circuit is more likely to suffer
problems from noise in the surrounding circuits, and potentially damage
whats connected to it- I don't know your application but good rule of thumb
if the manufacturers go to the cost of routing it to the outside world on a
pin do as they suggest and slap a cap to earth
regards
Anthony