LM7171AIMNOPB datasheet(21/30 Pages) NSC

21 / 30 page

LM7171

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SNOS760B – MAY 1999 – REVISED MARCH 2013

For example, for the LM7171 in a SOIC-8 package, the maximum power dissipation at 25°C ambient

temperature is 730 mW.

Thermal resistance,

θJA, depends on parameters such as die size, package size and package material. The

smaller the die size and package, the higher

θJA becomes. The 8-pin DIP package has a lower thermal

resistance (108°C/W) than that of 8-pin SOIC (172°C/W). Therefore, for higher dissipation capability, use an 8-

pin DIP package.

The total power dissipated in a device can be calculated as:

PD = PQ + PL

(3)

PQ is the quiescent power dissipated in a device with no load connected at the output. PL is the power dissipated

in the device with a load connected at the output; it is not the power dissipated by the load.

Furthermore,

PQ: = supply current × total supply voltage with no load

PL: = output current × (voltage difference between supply voltage and output voltage of the same side of

supply voltage)

For example, the total power dissipated by the LM7171 with VS = ±15V and output voltage of 10V into 1 kΩ is

PD = PQ + PL

= (6.5 mA) × (30V) + (10 mA) × (15V

− 10V)

= 195 mW + 50 mW

= 245 mW

Application Circuit

Figure 63. Fast Instrumentation Amplifier

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LM7171AIMNOPB Datasheet(PDF) 21 Page - National Semiconductor (TI)