TLV4110, TLV4111, TLV4112, TLV4113

FAMILY OF HIGH OUTPUT DRIVE OPERATIONAL

AMPLIFIERS WITH SHUTDOWN

SLOS289A – DECEMBER 1999 – REVISED APRIL 2000

12

POST OFFICE BOX 655303

APPLICATION INFORMATION

_

+

Rnull

RL

CL

Figure 26

general power design considerations

When driving heavy loads at high junction temperatures there is an increased probability of electromigration

affecting the long term reliability of ICs. Therefore for this not to be an issue either

The maximum continuous output current at a die temperature 150

°C will be 1/3 of the current at 105°C.

The junction temperature will be dependent on the ambient temperature around the IC, thermal impedance from

the die to the ambient and power dissipated within the IC.

Where

output of the IC.

Reducing one or more of these factors will result in a reduced die temperature. The 8-pin SOIC (small outline

integrated circuit) has a thermal impedance from junction to ambient of 176

°C/W. For this reason we

recommend that the maximum power dissipation of the 8-pin SOIC package be limited to 350 mW, with peak

dissipation of 700 mW as long as the RMS value is less than 350 mW.

The use of the MSOP PowerPAD

™ dramatically reduces the thermal impedance from junction to case. And with

correct mounting, the reduced thermal impedance will greatly increase the IC’s permissible power dissipation

and output current handling capability. For example, the power dissipation of the PowerPAD

™ is increased to

above 1 W. Sinusoidal and pulse-width modulated output signals will also increase the output current capability.

The equivalent dc current is proportional to the square-root of the duty cycle:

I

DC(EQ) +

I

Cont

(duty cycle)

CURRENT DUTY CYCLE

AT PEAK RATED CURRENT

EQUIVALENT DC CURRENT

AS A PERCENTAGE OF PEAK

100

100

70

84

50

71

Note that with an operational amplifier, a duty cycle of 70% would often result in the op amp sourcing current

70% of the time and sinking current 30%, therefore, the equivalent dc current would still be 0.84 times the

continuous current rating at a particular junction temperature.