• Support PF! Buy your school textbooks, materials and every day products Here!

Zener Diode behavior

  • #1
There is a variable Vin which goes through a resistor to a node (Vo) which then branches through a diode to a 3V source or to ground through a Zener diode.

I'm to sketch the graph of Vo as a function of Vin.

-4V < Vin < 4V
The resistor is 1K
The diode is CVD model, Von is .7V,
Vzener = 2.7V and Rzener = 100Ω

a picture is attached.

Can current flow through the Zener diode in both directions?

for example when Vin = -4V through -.7V will the zener diode operate like a normal diode?

and then cease operation until the reverse breakdown voltage of 2.7 through 3.7 volts is reached?

at 3.7 volts i assume all current would flow through the normal diode on top due to Rzener.
 

Attachments

Answers and Replies

  • #2
rude man
Homework Helper
Insights Author
Gold Member
7,631
717
There is a variable Vin which goes through a resistor to a node (Vo) which then branches through a diode to a 3V source or to ground through a Zener diode.

I'm to sketch the graph of Vo as a function of Vin.

-4V < Vin < 4V
The resistor is 1K
The diode is CVD model, Von is .7V,
Vzener = 2.7V and Rzener = 100Ω

a picture is attached.

Can current flow through the Zener diode in both directions?

for example when Vin = -4V through -.7V will the zener diode operate like a normal diode?

and then cease operation until the reverse breakdown voltage of 2.7 through 3.7 volts is reached?

at 3.7 volts i assume all current would flow through the normal diode on top due to Rzener.
Yes, current can flow in bot directions since the zener in the back direction looks like a reular diode, forward-biased.

EDIT: oops, not quite everything right.

A t some + input voltage Vin, the regular diode anode voltage Vd will exceed +3.7V and conduct. Any further increase in Vin will result in all of the ADDITIONAL current diverted thru the regular diode.

The point at which the regular diode starts to conduct is found from

(Vin - Vd)G1 = (Vd - Vz)G2 when Vd = +3.7V.

G1 = 1/1KΩ
G2 = 1/100Ω
Vz = 2.7V
 
Last edited:
  • #3
NascentOxygen
Staff Emeritus
Science Advisor
9,244
1,071
Can current flow through the Zener diode in both directions?
Yes.

for example when Vin = -4V through -.7V will the zener diode operate like a normal diode?
Precisely.

at 3.7 volts i assume all current would flow through the normal diode on top due to Rzener.
Not so. (I doubt that you mean what you wrote here.)
 

Related Threads on Zener Diode behavior

  • Last Post
Replies
6
Views
1K
  • Last Post
Replies
8
Views
2K
  • Last Post
Replies
1
Views
3K
  • Last Post
Replies
5
Views
4K
  • Last Post
Replies
9
Views
751
  • Last Post
Replies
19
Views
7K
  • Last Post
2
Replies
48
Views
5K
  • Last Post
Replies
6
Views
756
  • Last Post
Replies
1
Views
2K
  • Last Post
Replies
1
Views
910
Top