1SMB3EZ110 PANJIT [Pan Jit International Inc.], 1SMB3EZ110 Datasheet - Page 5

• Manufacturer Part Number: 1SMB3EZ110
• Description: SURFACE MOUNT SILICON ZENER DIODE(VOLTAGE - 11 TO 200 Volts Power - 3.0 Watts)
• Manufacturer: PANJIT [Pan Jit International Inc.]

APPLICATION NOTE:
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:
The temperature of the lead can also be measured using
a thermocouple placed on the lead as close as possible to
the tie point. The thermal mass connected to the tie point
is normally large enough so that it will not significantly
respond to heat surges generated in the diode as a result
of pulsed operation once steady-state conditions are
achieved. Using the measured value of T
temperature may be determined by:
Since the actual voltage available from a given zener
Lead Temperature, T
£c
and P
vary and depends on the device mounting method.
£c
tie points in common use and for printed circuit board
wiring.
LA
LA
is the lead-to-ambient thermal resistance (¢J /W)
is generally 30-40 ¢J /W for the various chips and
D
is the power dissipation. The value for £c
TL = £c
T
J
L
= T
, should be determined from:
L
LA
+ £G T
P
D
+ T
JL
A
L
, the junction
LA
will
of P
Changes in voltage, Vz, can then be found from:
will vary with time and may also be affected significantly
be the zener resistance. For best regulation, keep current
excursions as low as possible.
capability. Surge limitations are given in Figure 3. 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 3 be
exceeded.
£GT
lead temperature and may be found from Figure 2 for a
train of power pulses or from Figure 10 for dc power.
For worst-case design, using expected limits of Iz, limits
£c
found from Figures 5 and 6.
Under high power-pulse operation, the zener voltage
Data of Figure 2 should not be used to compute surge
D
VZ
and the extremes of T
JL
, the zener voltage temperature coefficient, is
is the increase in junction temperature above the
£GV = £c
£GT
JL
= £c
J
(£GT
VZ
LA
£GT
P
JL
D
J
) may be estimated.