THS4601

SLOS388B – OCTOBER 2001 – REVISED JUNE 2002

21

www.ti.com

APPLICATION INFORMATION

power dissipation and thermal characteristics

The THS4601 does not incorporate automatic thermal shutoff protection, so the designer must take care to

ensure that the design does not violate the absolute maximum junction temperature of the device. Failure may

result if the absolute maximum junction temperature of 150

°C is exceeded.

The thermal characteristics of the device are dictated by the package and the PC board. Maximum power

dissipation for a given package can be calculated using the following formula.

P

Tmax–TA

q

JA

Where:

For systems where heat dissipation is more critical, the THS4601 is offered in an 8-pin SOIC with PowerPAD.

The thermal coefficient for the SOIC PowerPAD is substantially improved over the traditional SOIC. Maximum

power dissipation levels are depicted in the graph for the two packages. The data for the 8DDA package

assumes a board layout that follows the PowerPAD layout guidelines.

0

0.5

1

1.5

2

2.5

3

–40

–20

0

2040

6080

8DDA Package

8D Package

θJA = 170°C/W for 8D,

θJA = 66.6°C/W for 8DDA

Ambient Temperature –

°C

MAXIMUM POWER DISSIPATION

vs

TEMPERATURE

Figure 40

When determining whether or not the device satisfies the maximum power dissipation requirement, it is

important to not only consider quiescent power dissipation, but also dynamic power dissipation. Often times,

this is difficult to quantify because the signal pattern is inconsistent, but an estimate of the RMS power

dissipation can provide visibility into a possible problem.