Current Sources and Voltage References

380

Characteristics of the zener diode

where T

L

is the lead temperature and R

θLA

is the lead-to-ambient thermal resistance

in ˚C/W. For DO-41 packages, this is typically between 30 to 40˚C/W.

Generally, the junction-to-ambient temperature difference (∆T) can be calculated from

the following:

where T

Jmax

is the maximum junction temperature; T

A

is the ambient temperature;

R

θJL

is the junction-to-lead thermal resistance; and P

Z

is the zener power dissipation.

The increase in junction temperature above the ambient temperature (∆T

JL

) can be

found by:

where R

θJL

is the junction-to-lead thermal resistance.

One can determine the junction temperature by:

Figure ...