# [Zener Diode] Current Ratings (IF,IFRM,IZM,IZSM)

Regarding the "Current Ratings of Zener Diode", this article will explain the information below.

• Current Ratings of Zener Diode
• Continuous Forward Current $$I_F$$
• Repetitive Peak Forward Current $$I_{FRM}$$
• Maximum Zener Current $$I_{ZM}$$
• Non-repetitive Peak Reverse Current $$I_{ZSM}$$

## Current Ratings of Zener Diode

The absolute maximum ratings in the datasheet of a zener diode show the current ratings.

The current ratings are listed in the following ways, although the information varies from datasheet to datasheet.

• Continuous Forward Current $$I_F$$
• Repetitive Peak Forward Current $$I_{FRM}$$
• Maximum Zener Current $$I_{ZM}$$
• Non-repetitive Peak Reverse Current $$I_{ZSM}$$

Each current rating is explained in turn below.

### Continuous Forward Current IF

"Continuous Forward Current $$I_F$$" listed in the absolute maximum ratings of zener diodes is the maximum average value of the forward current that can flow.

In the datasheet, "Continuous" is sometimes omitted and listed as "Forward Current $$I_F$$".

### Repetitive Peak Forward Current IFRM

Repetitive Peak Forward Current $$I_{FRM}$$" listed in the absolute maximum ratings of zener diodes is the peak value of repetitive forward current under specified conditions.

Unless otherwise specified, a half-wave sine wave with a pulse width of $$t_p=10{\mathrm{ms}}$$ is often the specified condition.

### Maximum Zener Current IZM

"Maximum Zener Current $$I_{ZM}$$" listed in the absolute maximum ratings of zener diodes is, as its name suggests, the maximum value of zener current.

To be more specific, "Maximum Zener Current $$I_{ZM})\" is the current value that can flow through the zener diode without exceeding the power rating. If the zener current \(I_Z$$ is large, the power applied to the zener diode ($$P_Z=I_Z×V_Z)$$ becomes large, which causes the zener diode to heat up ($$V_Z$$ is the zener voltage). If the temperature rating of the zener diode is exceeded as a result of the increased temperature, the diode may be damaged. Therefore, a maximum value is specified for the zener current.

### Non-repetitive Peak Reverse Current IZSM

"Non-repetitive Peak Reverse Current $$I_{ZSM}$$" listed in absolute maximum ratings of zener diodes is the non-repeatable peak value of zener surge current at specified conditions.

The specified conditions are described on the datasheet, for example, "$$t_p=100{\mathrm{μs}}$$, square wave, $$T_a=25{\mathrm{{^{\circ}C}}}$$ prior to surge".

"Non-repetitive Peak Reverse Current $$I_{ZSM}$$" is also called "Maximum Zener Surge Current $$I_{ZSM}$$".

#### Summary

In this article, the following information on the "Current Ratings of Zener Diode" was explained.

• Current Ratings of Zener Diode
• Continuous Forward Current $$I_F$$
• Repetitive Peak Forward Current $$I_{FRM}$$
• Maximum Zener Current $$I_{ZM}$$
• Non-repetitive Peak Reverse Current $$I_{ZSM}$$