Graph Vo vs Vin: Zener Diode Behavior

In summary: When Vin becomes +4V, the regular diode will conduct and will divert any additional current away from the zener. In summary, the conversation discussed the circuit of a variable Vin going through a resistor to a node (Vo), which then branches through a diode to a 3V source or to ground through a Zener diode. The graph of Vo as a function of Vin was also mentioned, with a range of -4V to 4V and a resistor of 1K. The diode was described as a CVD model with a Von of 0.7V, while the Zener diode had a Vzener of 2.7V and a resistance of 100Ω. It
  • #1
nwilkins259
9
0
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.
 

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  • #2
nwilkins259 said:
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
nwilkins259 said:
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 to Graph Vo vs Vin: Zener Diode Behavior

1. What is a Zener diode and how does it function in a circuit?

A Zener diode is a type of diode that is designed to operate in the reverse breakdown region, which means it can conduct current in the reverse direction when a specific voltage is applied. This allows it to regulate voltage in a circuit, preventing it from exceeding a certain level.

2. What is the purpose of plotting Vo against Vin in a graph for a Zener diode?

Plotting Vo against Vin allows us to visualize the behavior of the Zener diode in a circuit. It shows how the output voltage (Vo) changes as the input voltage (Vin) is varied. This can help us determine the breakdown voltage and regulation characteristics of the diode.

3. How does the breakdown voltage of a Zener diode affect its behavior in a circuit?

The breakdown voltage is the specific voltage at which a Zener diode starts to conduct in the reverse direction. This voltage determines the maximum voltage that can be applied to the diode without damaging it. Above the breakdown voltage, the diode behaves like a constant voltage source, regulating the voltage in the circuit.

4. What is the significance of the slope of the Zener diode behavior graph?

The slope of the Zener diode behavior graph represents its dynamic resistance, which is the change in output voltage with respect to the change in input voltage. A lower dynamic resistance indicates that the diode can regulate the voltage more efficiently.

5. How does temperature affect the behavior of a Zener diode?

Temperature has a significant impact on the behavior of a Zener diode. As the temperature increases, the diode's breakdown voltage decreases, and its dynamic resistance increases. This can cause a decrease in the diode's ability to regulate voltage, making it less efficient in a circuit.

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