9.4.3 Thermal Considerations

Restrict the maximum IC junction temperature to 125°C under normal operating conditions. Calculate the

maximum allowable dissipation, PD(max), and keep the actual power dissipation less than or equal to PD(max).

The maximum-power-dissipation limit is determined using Equation 11.

A

D max

JA

125

T

P

R

T

(11)

where

• TA is the maximum ambient temperature for the application

• RθJA is the junction-to-ambient thermal resistance given in Section 9.4.3

The TPS61033 comes in a SOT583 package. The real junction-to-ambient thermal resistance of the package

greatly depends on the PCB type, layout. Using larger and thicker PCB copper for the power pads (GND, SW,

and VOUT) to enhance the thermal performance. Using more vias connects the ground plate on the top layer

and bottom layer around the IC without solder mask also improves the thermal capability.

TPS61033

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