PZT2907AT1
INFORMATION FOR USING THE SOT-223 SURFACE MOUNT PACKAGE
POWER DISSIPATION
The power dissipation of the SOT-223 is afunction of the
input pad size. These can vary from the minimum pad size
for soldering to the pad size given for maximum power
dissipation. Power dissipation for asurface mount device is
determined byTJ(m=), the maximum ratedjunction tempera-
ture of the die, ReJA, the thermal resistance from the device
junction to ambient; and the operating temperature, TA.
Using the values provided on the data sheet for the SOT-223
package, PD can be calculated as follows.
PD=TJ(m~) -TA
R9JA
The values for the equation are found in the maximum
ratings table on the data sheet. Substituting these values into
MOUNTING
The melting temperature of solder is higher than the rated
temperature of the device. When the entire device is heated
to ahigh temperature, failure to complete soldering within a
short time could result in device failure. Therefore, the
following items should always be observed in order to
minimize the thermal stress to which the devices are
subjected.
.Always preheat the device.
●The delta temperature between the preheat and soldering
should be 10O°C or less.*
.When preheating and soldering, the temperature of t~
the equation for an ambient temperature TA of 25°C, one can
calculate the power dissipation of the device which in this
case is 1.5 watts.
.,.,,.~
$*$
The 83.3°CW for the SOT-223 package assu~~e~~g
recommended collector pad area of 965 sq. m~,~,~i~~fkss
epoxy printed circuit board to achieve apow$f m-~fion of
1.5 watts. If space is at apremium, q$~r&}ealistic
approach is to use the device at aPD ,~%m~ using the
footprint shown. Using aboard ma~erl~k~ch as Thermal
Clad, apower dissipation of 1.6 w~~~an be achieved using
the same footprint. ,1,‘.:%~\.,~
..‘,t!,,<$<}
,,.f$’:*”,. ‘$,,:.,
....,
●The soldering tewatuk and time should not exceed
260°C for more,t$@XO seconds.
●When shiftin~~~ro~,‘preheating to soldering, the maximum
temperat@,-nt should be 5°C or less.
.After sddek has been completed, the device should be
alloM,., to cool naturally for at least three minutes.
Q@~a~cooling should be used as the use of forced
‘~,$~/~& will increase the temperature gradient and result
:i$~:~~;latentfailure due to mechanical stress.
Y•’~~echanical stress or shock should not be applied during _
cooling
leads and the case must not exceed the maxi~~’~?:,
temperature ratings as shown on the data shee~.- —
●Soldering adevice without preheating can cause excessive
using infrared heating with the reflow solderin$~~$@d, thermal shock and stress which can result in damage to the
the difference should be a maximum of 10°C.:&Lk,yJF’$ device.
,),>-?:<:;’:
,?1:
MINIMUM RECOMMENQ~k+~OTPRINT FOR SURFACE MOUNTED APPLICATIONS ‘
;*
Surface mount board layout is acri~$~ ##on of the total interface between the board and the package. With the
design. The footprint for the semi-r packages must correct pad geometry, the packages will self align when
be the correct size to insur~~~~$? solder connection subjected to asolder reflow process.
4
0.079 1
L0.059 0.059 0.059 (–)
inches
T1.5 Tmm —
—
4Motorola Small+gnal Transistors, FETs and Diodes Device Data