PD(MAX) =

150°C ± 125°C

109.1°C/W

= 0.23W

PD(MAX) =

150°C ± 125°C

161.1°C/W

= 0.16W

PD(MAX) =

150°C ± 25°C

109.1°C/W

= 1.15W

PD(MAX) =

150°C ± 25°C

161.1°C/W

= 0.78W

PD(MAX) =

TJ(MAX) - TA

R

TJA

LM7332

SNOSAV4B – APRIL 2008 – REVISED JANUARY 2016

www.ti.com

Output Short Circuit Current and Dissipation Issues (continued)

The operational amplifier quiescent power dissipation is calculated by Equation 6:

PQ = IS × VS

where

•

IS: Supply Current

•

VS: Total Supply Voltage (V

+ − V−)

(6)

The DC load power is calculated by Equation 7:

PDC = IO × (Vr – Vo)

where

•

VO: Average Output Voltage

•

Vr: V

+ for sourcing and V− for sinking current

(7)

The AC load power is calculated as PAC = the value shown in Table 1.

Table 1 shows the maximum AC component of the load power dissipated by the operational amplifier for

standard sinusoidal, triangular, and square waveforms:

Table 1. Normalized AC Power Dissipated in the Output Stage for Standard

Waveforms

PAC (W.Ω/V

2)

SINUSOIDAL

TRIANGULAR

SQUARE

50.7 x 10−3

46.9 x 10−3

62.5 x 10−3

The table entries are normalized to VS

2/R

L. To figure out the AC load current component of power dissipation,

simply multiply the table entry corresponding to the output waveform by the factor VS

2/R

L. For example, with ±12-

V supplies, a 600-

Ω load, and triangular waveform power dissipation in the output stage is calculated as:

PAC = (46.9 × 10

−3) × [242/600] = 45.0 mW

(8)

The maximum power dissipation allowed at a certain temperature is a function of maximum die junction

temperature (TJ(MAX)) allowed, ambient temperature TA, and package thermal resistance from junction to ambient,

RθJA.

(9)

For the LM7332, the maximum junction temperature allowed is 150°C at which no power dissipation is allowed.

The power capability at 25°C is given by Equation 10 and Equation 11.

For VSSOP package:

(10)

For SOIC package:

(11)

Similarly, the power capability at 125°C is given by Equation 12 and Equation 13.

For VSSOP package:

(12)

For SOIC package:

(13)

24

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