Continue to Site

Welcome to EDAboard.com

Welcome to our site! EDAboard.com is an international Electronics Discussion Forum focused on EDA software, circuits, schematics, books, theory, papers, asic, pld, 8051, DSP, Network, RF, Analog Design, PCB, Service Manuals... and a whole lot more! To participate you need to register. Registration is free. Click here to register now.

Register Log in

free wheeeling diode help?

Status
Not open for further replies.
S

Shreehari

Member level 4
Joined
Jun 18, 2010
Messages
68
Helped
1
Reputation
2
Reaction score
1
Trophy points
1,288
Location
mangalore
Activity points
1,735
Hello
My ARM Board consists of digital outputs.In their document they had given that"user has to add proper free wheeling diodes across inductive loadsto protect the output transistors against high voltage".

What I have to now to get the output?what are freewheeling diodes?

Thanks
 

Flyback diode (sometimes called a snubber diode,
freewheeling diode, suppressor diode, or catch diode) is
a diode used to eliminate flyback, the sudden voltage spike
seen across an inductive load when its supply voltage is
suddenly reduced or removed ..
see:
https://everything2.com/title/flywheel+diode

I don’t know your ARM board, but mu guess is that it has some Open-Collector (digital) on/off outputs that can sink a couple of hundreds of mA, so a load (relay, bulb, LED) can be connected between Vcc and the output pin ..
Find out in the data sheet what the max sinking current is, and never connect a load that may require more current that the output can handle ..

IanP
:D
 
it is written that max output current is 0 - 5A.What s the value of load that I should connect?
 

According to your information, anything up to 5A ..
The data sheet should also specify voltage limits, so keep that in mind too ..

IanP
:D
 

    S

    Shreehari

    Points: 2
    Helpful Answer Positive Rating
I need a clarification in this,

how is the path of that free wheeling current ?
Is it towards the power source or will it be circulating within the loop of Inductor and the diode until it discharges to zero ?
 

When the current flow to an inductor (and an AC induction motor certainly is one) is suddenly interrupted, the inductor tries to maintain
the current by reversing polarity and increasing the voltage. Without the "freewheeling diode" the voltage can go high enough to damage the
switching device (IGBT, Thyristor, etc.). With it, the reverse current is allowed to flow through the diode and dissipate.
 
NO. I am not into any arguments.
The thing is i dont know.

So say, for eg:- the source is a regulator (eg LM7812)
U mean the free wheeling current flows to the output pin of the regulator? and then ?
 

If you put your free wheeling diode (D) across the inductor (L), the free wheeling current will never go back to the source, it only "turns" in the L-D circuit until vanishing due to dissipation inside D and L.
 

    S

    Shreehari

    Points: 2
    Helpful Answer Positive Rating
Monnoliv is correct,

the reason of fly back is to provide it a circular path, so that current passes through it and dissipates off through the components , and it never goes back to the source...
 

Status
Not open for further replies.

Similar threads

Part and Inventory Search

Welcome to EDABoard.com

Sponsor

Back
Top