Can I substitute a (2) CES388 Diodes for a RB480K

[Rshusko]

Hi All,

I am trying to wire up a fairly sensitive display that calls out for 2 RB480K diodes to be connected in series as a reference (GND C A C A). I was given CES388 diodes as a substitution but since I have installed them the display has not worked. To me, I'm a mechanical engineer, the properties seem fairly similar but I could be missing something as I am not used to doing electrical work. Any help is appreciated. if it helps the display is a US micro products P21301 in SPI mode. Thanks!

 

[davenn]

show/tell us more about your circuit and where these diodes need to be placed
a schematic would be helpful

it could be that the capacitance and or forward voltage drop differences between the 2 devices is what is making the circuit not work

Dave

 

[Jeff Rosenbury]

Yes. The diodes are used for a voltage reference.

I would go with the right part. I doubt it makes a difference because they are nearly identical, but why worry?

BTW, the Rohm diodes (RB480K) have a slightly higher current and capacitance. That means they will have a slightly lower forward bias voltage for a given current. But the value will be in the mV range. Since the spec calls for that diode pair or a similar one, this is likely not the problem. Still, it could be. So until you get it working, go with the Rohm. Just don't expect that to fix the problem.

 

[Rshusko]

Yes. The diodes are used for a voltage reference.

I would go with the right part. I doubt it makes a difference because they are nearly identical, but why worry?

BTW, the Rohm diodes (RB480K) have a slightly higher current and capacitance. That means they will have a slightly lower forward bias voltage for a given current. But the value will be in the mV range. Since the spec calls for that diode pair or a similar one, this is likely not the problem. Still, it could be. So until you get it working, go with the Rohm. Just don't expect that to fix the problem.

Thanks for the answer! I believe this is the case. I must have messed something else when I put in the diodes. I'll get the correct diodes in as well just to be safe.