What role does an element play(shematic question)?

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intiCA

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Hello everyone,
Could anyone shed the light on what role does an element play in this particular case. A picture attached.
I mean shottky diode (SB150).

Thank you.
 

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Perhaps just protection against reverse transients. If we could see where it was coming from that would help.
 
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    intiCA

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asdf44 said:
Perhaps just protection against reverse transients. If we could see where it was coming from that would help.
Click to expand...

it's just a control for inputs Transmit (Enable) TTL '1', Receive (Enable) TTL '0'.
 

It serves no purpose at all in the schematics you show. I would guess it protects against something wrong on the signal driving the enable lines or protects other circuits in the event of a ground fault between the two ends putting excessive offset on the control signal.

Brian.
 
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    intiCA

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Hi,

Yes, I agree. It looks like it is probably/possibly just to keep negative going transients from going lower than e.g. ~-150mV to ~-300mV. Sometimes in simulations at turn-off signals don't stop at 0V/0A but go a lot lower and would damage devices.
 
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    intiCA

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Yes, that's exactly what it does. It prevents the voltage at that pin from going too negative below GND. It is also very often used at the PWM controller outputs to MOSFETs in SMPS.
 
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    intiCA

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