5.6

Maximum power dissipation

The maximum power supply voltage, as well as the usable output load current drive is limited by the maximum

power dissipation allowed by the device package. The absolute maximum junction temperature for the TSB952 is

150 °C. The junction temperature can be estimated as follows:

TJ=PD×RtℎJA+TA

(3)

TJ is the die junction temperature.

PD is the power dissipated in the package.

RTH-JA is the junction to ambient thermal resistance of the package.

TA is the ambient temperature.

The RTH-JA, given in table x for the available packages, is based on the JEDEC standard JESD51, for 2s2p (4

layers) board. This value largely depends on the board layout and is given as a guideline. Be aware that the

actual value can differ significantly, and optimize the power dissipation on your board if this is critical for your

design. For thermally sensitive designs, favor the DFN8 version of the product that has better thermal dissipation

due to its exposed pad.

The power dissipated in the package PD is the sum of the quiescent power dissipated and the power dissipated

by the output stage transistor. It is calculated as follows:

PD= VCC×ICC + Vcc++VOUT ×ILoadwhentheopampissourcingthecurrent.

PD= VCC×ICC + VOUT+VCC− ×ILoadwhentheopampissinkingthecurrent.

Do not exceed the 150 °C maximum junction temperature for the device. Exceeding the junction temperature limit

can cause degradation in the parametric performance or even destroy the device.

Due to the Rth-ja value, the SO8 package cannot be used at VCC = 36 V and at 125 °C ambient temperature,

because the maximum junction temperature would be reached. The following figure shows the maximum VCC for

a given ambient temperature, considering only the device maximum ICC (output current is negligible).

Figure 45. Maximum VCC for safe operation using SO8 package

Considering the output current limitation, the figures below give the maximum output current for a given output

voltage and temperature, at VCC = 36 V, for SO8 and DFN8 packages.

TSB952

Application information

DS14576 - Rev 1

page 20/36