THS3095D datasheet(26/46 Pages) TI2

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9.4.1.2 Power Dissipation and Thermal Considerations

The THS309x incorporates automatic thermal shutoff protection. This protection circuitry shuts down the

amplifier if the junction temperature exceeds approximately 160°C. When the junction temperature reduces

to approximately 140°C, the amplifier turns on again. But, for maximum performance and reliability, the designer

must ensure that the design does not exceed a junction temperature of 125°C. Between 125°C and 150°C,

damage does not occur, but the performance of the amplifier begins to degrade and long-term reliability suffers.

The thermal characteristics of the device are dictated by the package and the PCB. Maximum power dissipation

for a given package is calculated using the following equation:

PDmax = Tmax − TA

θJA

(6)

Where:

• PDmax is the maximum power dissipation in the amplifier (W).

• Tmax is the absolute maximum junction temperature (°C)

• TA is the ambient temperature (°C)

• θJA = θJC + θCA

• θJC is the thermal coefficient from the silicon junctions to the case (°C/W)

• θCA is the thermal coefficient from the case to ambient air (°C/W)

For systems where heat dissipation is more critical, the THS3091 and THS3095 are offered in an 8-pin

SOIC (DDA) with PowerPAD package. The thermal coefficient for the PowerPAD packages are substantially

improved over the traditional SOIC. The data for the PowerPAD packages assume a board layout that follows

the PowerPAD layout guidelines referenced above and detailed in the PowerPAD™ Thermally Enhanced

Package application note. If the PowerPAD is not soldered to the PCB, then the thermal impedance increases

substantially, which can cause serious heat and performance issues. Be sure to always solder the PowerPAD to

the PCB to optimize performance.

When determining whether or not the device satisfies the maximum power-dissipation requirement, consider not

only quiescent power dissipation, but also dynamic power dissipation. Often times, ynamic power dissipation 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.

THS3091, THS3095

SLOS423K – SEPTEMBER 2003 – REVISED APRIL 2023

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THS3095D Datasheet(PDF) 26 Page - Texas Instruments