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THERMAL INFORMATION

P

D

max + VI(avg) * VO(avg)

I

O(avg) )

V

I(avg)

x I

(Q)

(1)

A

B

C

A

B

C

A

B

C

(a)

(b)

TO–263 Package

TO–220 Package

TPS75601, TPS75615

TPS75618, TPS75625

TPS75633

SLVS329C – JUNE 2001 – REVISED MARCH 2004

The amount of heat that an LDO linear regulator generates is directly proportional to the amount of power it

above which normal operation is not assured. A system designer must design the operating environment so that

main environmental variables that a designer can use to improve thermal performance are air flow and external

heatsinks. The purpose of this information is to aid the designer in determining the proper operating environment

for a linear regulator that is operating at a specific power level.

Where:

• V

• V

• I

• I

For most TI LDO regulators, the quiescent current is insignificant compared to the average output current;

temperature rise is computed by multiplying the maximum expected power dissipation by the sum of the thermal

device, the more surface area available for power dissipation and the lower the object's thermal resistance.

Figure 21 illustrates these thermal resistances for (a) a TO-220 package attached to a heatsink, and (b) a

TO-263 package mounted on a JEDEC High-K board.

Figure 21. Thermal Resistances

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