3. SURGE CURRENT (Ir) - Surge current is specified as the maximum allowable peak, non-recurrent square-wave

current with a pulse width, PW, of 8.3 ms. The data given in Figure 5 may be used to find the maximum surge

current for a quare wave of any pulse width between 1 ms and 1000ms by plotting the applicable points on

logarithmic paper. Examples of this, using the 6.8v and 200V zeners, are shown in Figure 6. Mounting

¡Ï¢·

¡Ð¢±

¢J ).

4. VOLTAGE REGULATION (£GVz) - Test conditions for voltage regulation are as follows: Vz measurements are made

at 10% and then at 50% of the Iz max value listed in the electrical characteristics table. The test currents are the

same for the 5% and 10% tolerance devices. The test current time druation for each Vz measurement is 40 ¡Ó 10 ms.

¡Ï¢·

¡Ð¢±

¢J ). Mounting contact located as specified in Note2.

APPLICATION NOTE:

Since the actual voltage available from a given zener

diode is temperature dependent, it is necessary to

determine

junction

temperature

under

any

set

of

operating conditions in order to calculate its value. The

following procedure is recommended:

£c

lead temperature and may be found from Figure 3 for

a train of power pulses or from Figure 4 for dc power.

For worst-case design, using expected limits of Iz, limits

Changes in voltage, Vz, can then be found from:

£c

from Figures 2.

Under high power-pulse operation, the zener voltage will

vary with time and may also be affected significantly be

the zener resistance. For best regulation, keep current

excursions as low as possible.

Data of Figure 3 should not be used to compute surge

capability. Surge limitations are given in Figure 5. They

are lower than would be expected by considering only

junction temperature, as current crowding effects cause

temperatures to be extremely high in small spots resulting

in device degradation should the limits of Figure. 5 be

exceeded.

SMCJ5348 thru SMCJ5388

MCC