Continue to Site

# Looking for zener diode model.

Status
Not open for further replies.

#### Lightium

##### Active Member
Hello everyone,

I am looking for a spice 3 model of the 1N4109.

While you are waiting to find one if one exists. It might be quicker to roll your own approximation from the datasheet. From the LTspice Help file:

D. Diode
A diode requires a .model card to specify its characteristics. There are two types of diodes available. One is a conduction region-wise linear model that yields a computationally light weight representation of an idealized diode. It has three linear regions of conduction: on, off and reverse breakdown. Forward conduction and reverse breakdown can non-linear by specifying a current limit with Ilimit(revIlimit). tanh() is used to fit the slope of the forward conduction to the limit current. The parameters epsilon and revepsilon can be specified to smoothly switch between the off and conducting states. A quadratic function is fit between the off and on state such that the diode's I-V curve is continuous in value and slope and the transition occurs over a voltage specified by the value of epsilon for the off to forward conduction and revepsilon for the transition between off and reverse breakdown.

Below are the model parameters for this type of diode:

 Name Description Units Default Ron Resistance in forward conduction mΩ 1.0 Roff Resistance when off Ω 1/Gmin Vfwd Forward threshold voltage to enter conduction V 0.0 Vrev Reverse breakdown voltage V Infin. Rrev Breakdown impedance Ω Ron Ilimit Forward current limit A Infin. Revilimit Reverse current limit A Infin. Epsilon Width of quadratic region V 0.0 Revepsilon Width of reverse quad. region V 0.0
This idealized model is used if any of Ron, Roff, Vfwd, Vrev or Rrev is specified in the model.

Hello Papabravo. No I can't roll my own, too lazy today.

When I get around to it because I am sure one doesn't exist, I will post it.

Sure. It's all up to your level of motivation. The piecewise linear conduction model is easier to deal with than the alternative.

.MODEL 1N4109 D BV=15 IS=5.72393f CJO=73.3167p IBV=50u VJ=0.75

I got it from my LTspice group.

.MODEL 1N4109 D BV=15 IS=5.72393f CJO=73.3167p IBV=50u VJ=0.75

I got it from my LTspice group.
If you're happy, then so am I. You might want to check on the default values for the other parameters to avoid surprises. In particular there is the emission coefficient, N, which defaults to 1.0

See Diodes.com. They are very good for diode models compatible with LTspice

See Diodes.com. They are very good for diode models compatible with LTspice
Yes, but do they have 1N4109 zeners?

Last edited:
Yes, but do they have 1N4109 zeners?
It would appear that they do not have that particular device.

Why would you choose 1N4109's?

They are rather old/unpopular and many better choices for cost, performance and availability exist.

Why would you choose 1N4109's?

They are rather old/unpopular and many better choices for cost, performance and availability exist.
It is not clear that the TS needs to obtain them. More likely he has some and wants to investigate their suitability.

Yes, but do they have 1N4109 zeners?

You might approach the need for a spice model differently. What zener characteristic is critical to your circuit design?

The 1N4109 have poor specs e.g. 100 Ohms max vs others with <=30 ohms max at 50uA.

You might approach the need for a spice model differently. What zener characteristic is critical to your circuit design?
That is why I suggested he use the piecewise linear diode model available in LTspice and perhaps other spice packages as well. See the description in post #2

You might approach the need for a spice model differently. What zener characteristic is critical to your circuit design?
15 volts 300mW through-hole zener diode.

Last edited:
That is why I suggested he use the piecewise linear diode model available in LTspice and perhaps other spice packages as well. See the description in post #2
Papabravo, I'll try the piecewise linear model on the weekend.

Be sure to compare it with the model in your post #6 for good measure. You should be able to get what you need with a DC sweep from -17V to +2V and some current limiting. this is simulation and you can stress the hell out of model without the agony of letting out the magic smoke

I believe I found a more modern device to replace the 1N4109. The BZX55C15-TAP, but still no model.

I believe I found a more modern device to replace the 1N4109. The BZX55C15-TAP, but still no model.
What exactly are you using it for?, I would have thought there's little need to simulate a zener?.

Status
Not open for further replies.

Replies
2
Views
4K
Replies
3
Views
1K
Replies
11
Views
11K
Replies
3
Views
2K
Replies
2
Views
2K