Hello All,

What kind of overvoltage circuit should I go for to protect my current circuit that is working at 5Volt. Input voltage is around 6.5V and I have a voltage regulator in it.
If the input voltage is bumped to 60-70V what kind of protection can i do such that the voltage drops down to appropriate level. Zener diode? TVS diode?
Not a fuse or a voltage regulator solution.

Thank you in advance

 

A TVS would be the easiest solution.

 

Is the 60V a transient, or a prolonged condition?

 

a prolonged condition...need to test it for couiple of minutes at that voltage

 

I misread your question. Post a schematic so we can see how the 5V is generated. Not many 5V regulators will tolerate a 60V differential.

 

Hello,

It all depends on how many current is needed for this 5 Volts.
The LM317HV will allow 60 Volts as absolute maximum as input voltage.
And the TL783 will even allow 125 Volts at its input.

Bertus

 

there is a voltage regulator and supply current is upto 400mA of the voltage regulator. It can take upto 18V max. So definitely the voltage In needs to be dropped way low if a 60V is connected.

Not supposed to use a another voltage regulator to regulate the 60V input... need to use a zener diode or TVS diode or some overvoltage protection circuit to drop the voltage down to less than 12V.

 

Curiosity...What are you building that takes 5V but could "somehow" be connected to 60-70V for a prolonged time? Or better.. where is that high voltage coming from or how could that happen..

 

Its not coming from anywhere.. I am just supposed to design a overvoltage protection that can withstand such high voltage and connect to that voltage and demonstrate it

 

What is the load and how many current you need?

 

Its not coming from anywhere.. I am just supposed to design a overvoltage protection that can withstand such high voltage and connect to that voltage and demonstrate it

ohhh.. so homework and you're cheating by having someone give you the answer

 

What is the load and how many current you need?

load is a voltage regulator then the voltage regulator supplied power to PIC chip. I wont be using more than 500mA at max.
I have already finished the schematic and completed the software... and now final step is the overvoltage protection... i have bunch of options such as use zener diode TVS diode but not really much experience behind such huge voltage input and providing a huge voltage drop.

 

ohhh.. so homework and you're cheating by having someone give you the answer

More like guidance in the right direction is what I am looking for... and also what sort of calculations. An article of some sort on this etc... its all about learning doesnt matter where I can learn from

 

Hello,

If you want to know more about zener diodes, have a look at this page of the eBook:
http://www.allaboutcircuits.com/textbook/semiconductors/chpt-3/zener-diodes/

Bertus

 

Thanks Bertus I can do that... but does this page explain about zener diode how cna it be used for overvoltage protection for high voltages?

 

load is a voltage regulator then the voltage regulator supplied power to PIC chip. I wont be using more than 500mA at max.
I have already finished the schematic and completed the software... and now final step is the overvoltage protection... i have bunch of options such as use zener diode TVS diode but not really much experience behind such huge voltage input and providing a huge voltage drop.

As what you need, the zener diode may not give you enough current, or you have to choose a big current one, so you may use TVS, and which voltage regular are you using?

 

the voltage regulator is this one. ZLDO1117G50DITR-ND
http://www.diodes.com/datasheets/ZLDO1117.pdf

 

As what you need, the zener diode may not give you enough current, or you have to choose a big current one, so you may use TVS, and which voltage regular are you using?

Can you explain me why will zener diode not give enough current?
TVs diode (transient voltage supressor) as the name suggests is good for ESD issues that give high transient voltages for a brief moment of time isn't ti? My application I am going to give high voltage for couple of minutes.

 

the
Not supposed to use a another voltage regulator to regulate the 60V .

As far as I know there is no law that requires that.

 

As far as I know there is no law that requires that.

It's part of the task I am supposed to do... using another regulator wouldn't be a overprotection circuit design anymore. It will be just using another IC.