TPS75201Q, TPS75215Q, TPS75218Q, TPS75225Q, TPS75233Q WITH RESET

TPS75401Q, TPS75415Q, TPS75418Q, TPS75425Q, TPS75433Q WITH POWER GOOD

FAST-TRANSIENT-RESPONSE 2-A LOW-DROPOUT VOLTAGE REGULATORS

SLVS242B – MARCH 2000 – REVISED JUNE 2003

21

POST OFFICE BOX 655303

THERMAL INFORMATION

thermally enhanced TSSOP-20 (PWP – PowerPad

)

The thermally enhanced PWP package is based on the 20-pin TSSOP, but includes a thermal pad [see

Figure 25(c)] to provide an effective thermal contact between the IC and the PWB.

Traditionally, surface mount and power have been mutually exclusive terms. A variety of scaled-down

TO220-type packages have leads formed as gull wings to make them applicable for surface-mount applications.

These packages, however, suffer from several shortcomings: they do not address the very low profile

requirements (< 2 mm) of many of today’s advanced systems, and they do not offer a pin-count high enough

to accommodate increasing integration. On the other hand, traditional low-power surface-mount packages

require power-dissipation derating that severely limits the usable range of many high-performance analog

circuits.

The PWP package (thermally enhanced TSSOP) combines fine-pitch surface-mount technology with thermal

performance comparable to much larger power packages.

The PWP package is designed to optimize the heat transfer to the PWB. Because of the very small size and

limited mass of a TSSOP package, thermal enhancement is achieved by improving the thermal conduction

paths that remove heat from the component. The thermal pad is formed using a lead-frame design (patent

pending) and manufacturing technique to provide the user with direct connection to the heat-generating IC.

When this pad is soldered or otherwise coupled to an external heat dissipator, high power dissipation in the

ultrathin, fine-pitch, surface-mount package can be reliably achieved.

DIE

Side View (a)

End View (b)

Bottom View (c)

DIE

Thermal

Pad

Figure 25. Views of Thermally Enhanced PWP Package

Because the conduction path has been enhanced, power-dissipation capability is determined by the thermal

considerations in the PWB design. For example, simply adding a localized copper plane (heat-sink surface),

which is coupled to the thermal pad, enables the PWP package to dissipate 2.5 W in free air (reference

power dissipation range for the component. The power dissipation limit can be further improved by adding

performance at the minimum recommended heat-sink size, illustrated in Figure 29.