Data Sheet

30

Rev. 1.2, 2014-07-03

TLE42994

Application Information

6.3

Thermal Considerations

Knowing the input voltage, the output voltage and the load profile of the application, the total power dissipation

can be calculated:

(4)

with

•

P

•

V

•

V

•

I

•

I

The maximum acceptable thermal resistance

R

(5)

with

•

T

•

T

Based on the above calculation the proper PCB type and the necessary heat sink area can be determined with

reference to the specification in “Thermal Resistance” on Page 13.

Example

Application conditions:

V

V

I

T

Calculation of

R

P

= (13.5 V – 5 V) • 50 mA + 13.5 V • 2 mA

= 0.425 W + 0.027 W

= 0.452 W

R

= (150 °C – 125 °C) / 0.452 W

= 55.3 K/W

As a result, the PCB design must ensure a thermal resistance

R

TLE42994E (PG-SSOP-14 EP package) and according to “Thermal Resistance” on Page 13, at least 600 mm²

heatsink area is needed on the FR4 1s0p PCB, or the FR4 2s2p board can be used.

–

() I

Q

×

+

×

=

,

,

–

----------------------------

=