
TPS75201-EP TPS75215-EP TPS75218-EP TPS75225-EP TPS75233-EP WITH RESET
TPS75401-EP
’
75415-EP
’
75418-EP
’
75425-EP
’
75433-EP WITH POWER GOOD
FAST-TRANSIENT-RESPONSE 2-A LOW-DROPOUT VOLTAGE REGULATORS
SGLS165
–
APRIL 2003
25
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
THERMAL INFORMATION
thermally enhanced TSSOP-20 (PWP
–
PowerPad
) (continued)
If the system implements a TPS75233QPWPEP regulator, where V
I
= 5 V and I
O
= 800 mA, the internal power
dissipation is:
PD(total)
VI
VO
IO
(5
3.3)
0.8
1.36 W
(9)
Comparing P
D(total)
with P
D(max)
reveals that the power dissipation in this example does not exceed the calculated
limit. When it does, one of two corrective actions should be made: raising the power-dissipation limit by increasing
the airflow or the heat-sink area, or lowering the internal power dissipation of the regulator by reducing the input
voltage or the load current. In either case, the above calculations should be repeated with the new system
parameters.
mounting information
The primary requirement is to complete the thermal contact between the thermal pad and the PWB metal. The
thermal pad is a solderable surface and is fully intended to be soldered at the time the component is mounted.
Although voiding in the thermal-pad solder-connection is not desirable, up to 50% voiding is acceptable. The data
included in Figures 26 and 27 is for soldered connections with voiding between 20% and 50%. The thermal analysis
shows no significant difference resulting from the variation in voiding percentage.
Figure 29 shows the solder-mask land pattern for the
PWP package. The minimum recommended heat-
sink area is also illustrated. This is simply a copper
plane under the body extent of the package, including
metal routed under terminals 1, 10, 11, and 20.
Figure 29. PWP Package Land Pattern
Location of Exposed
Thermal Pad on
PWP Package
Minimum Recommended
Heat-Sink Area