NAME_TABLE:

C_Function_Name: cm_zener

Spice_Model_Name: zener

Description: "zener diode"

PORT_TABLE:

Port Name: z

Description: "zener"

Direction: inout

Default_Type: gd

Allowed_Types: [gd]

Vector: no

Vector_Bounds: -

Null_Allowed: no

PARAMETER_TABLE:

Parameter_Name: v_breakdown i_breakdown

Description: "breakdown voltage" "breakdown current"

Data_Type: real real

Default_Value: - 2.0e-2

Limits: [1.0e-6 1.0e6] [1.0e-9 -]

Vector: no no

Vector_Bounds: - -

Null_Allowed: no yes

PARAMETER_TABLE:

Parameter_Name: i_sat n_forward

Description: "saturation current" "forward emission coefficient"

Data_Type: real real

Default_Value: 1.0e-12 1.0

Limits: [1.0e-15 -] [0.1 10]

Vector: no no

Vector_Bounds: - -

Null_Allowed: yes yes

PARAMETER_TABLE:

Parameter_Name: limit_switch

Description: "switch for on-board limiting (convergence aid)"

Data_Type: boolean

Default_Value: FALSE

Limits: -

Vector: no

Vector_Bounds: -

Null_Allowed: yes

STATIC_VAR_TABLE:

Static_Var_Name: previous_voltage

Data_Type: pointer

Description: "iteration holding variable for limiting"

• Description:
  The Zener Diode models the DC characteristics of most zeners. This model differs from the Diode/Rectifier by providing a user-defined dynamic resistance in the reverse breakdown region. The forward characteristic is defined by only a single point, since most data sheets for zener diodes do not give detailed characteristics in the forward region.
  The first three parameters define the DC characteristics of the zener in the breakdown region and are usually explicitly given on the data sheet.
  The saturation current refers to the relatively constant reverse current that is produced when the voltage across the zener is negative, but breakdown has not been reached. The reverse leakage current determines the slight increase in reverse current as the voltage across the zener becomes more negative. It is modeled as a resistance parallel to the zener with value v breakdown / i rev.
  Note that the limit switch parameter engages an internal limiting function for the zener. This can, in some cases, prevent the simulator from converging to an unrealistic solution if the voltage across or current into the device is excessive. If use of this feature fails to yield acceptable results, the convlimit option should be tried (add the following statement to the SPICE input deck: .options convlimit)

Example SPICE Usage:

a9 3 4 vref10

.

.

.model vref10 zener(v_breakdown=10.0 i_breakdown=0.02

+ r_breakdown=1.0 i_rev=1e-6 i_sat=1e-12)