SNOSAW8 Data sheet

SNOSAW8F May 2008 – July 2026 LM7321 , LM7322

PRODUCTION DATA

Package Options

Mechanical Data (Package|Pins)

D|8
- MSOI002K
DBV|5
- MPDS018T

Thermal pad, mechanical data (Package|Pins)

Orderable Information

6.3.1 Output Short Circuit Current and Dissipation Issues

The LM732xx output stage is designed for maximum output current capability. Even though momentary output shorts to ground and either supply can be tolerated at all operating voltages, longer lasting short conditions can cause the junction temperature to rise beyond the absolute maximum rating of the device, especially at higher supply voltage conditions. Below supply voltage of 6V, the output short circuit condition can be tolerated indefinitely.

With the op amp tied to a load, the device power dissipation consists of the quiescent power due to the supply current flow into the device, in addition to power dissipation due to the load current. The load portion of the power can include an average value (due to a DC load current) and an AC component. DC load current flows if there is an output voltage offset, or the output AC average current is non-zero, or if the op amp operates in a single supply application where the output is maintained somewhere in the range of linear operation.

Therefore,

Equation 1.

P_{T O T A L} = P_{Q} + P_{D C} + P_{A C}

The Op Amp Quiescent Power Dissipation is calculated as:

Equation 2.

P_{Q} = I_{S} \times V_{S}

where

I_S: Supply Current
V_S: Total Supply Voltage (V⁺ − V⁻)

The DC Load Power is calculated as:

Equation 3.

P_{D C} = I_{O} \times (V_{r} - V_{o})

where

V_O: Average Output Voltage
V_r: V⁺ for sourcing and V⁻ for sinking current

The AC Load Power is calculated as P_AC = See Table 6-1.

Table 6-1 shows the maximum AC component of the load power dissipated by the op amp for standard Sinusoidal, Triangular, and Square Waveforms:

Table 6-1 Normalized AC Power Dissipated in the Output Stage for Standard Waveforms

P_AC (W.Ω/V²)
Sinusoidal	Triangular	Square
50.7 × 10⁻³	46.9 × 10⁻³	62.5 × 10⁻³

The table entries are normalized to V_S²/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 V_S²/R_L. For example, with ±12V supplies, a 600Ω load, and triangular waveform power dissipation in the output stage is calculated as:

Equation 4.

P_{A C} = (46.9 \times 10^{- 3}) \times (\frac{576}{600}) = 45.0 m W

The maximum power dissipation allowed at a certain temperature is a function of maximum die junction temperature (T_J(MAX)) allowed, ambient temperature T_A, and package thermal resistance from junction to ambient, θ_JA.

Equation 5.

P_{D (M A X)} = \frac{T_{J (M A X)} - T_{A}}{θ_{J A}}

For the LM732xx, the maximum junction temperature allowed is 150°C at which no power dissipation is allowed. The power capability at 25°C is given by the following calculations:

For VSSOP package (dual channel):

Equation 6.

P_{D (Max) = \frac{150 ° C - 25 ° C}{169.6 ° C} = 0.737 W}

For SOIC package (single channel):

Equation 7.

P_{D (Max) = \frac{150 ° C - 25 ° C}{133.5 ° C} = 0.936 W}

Similarly, the power capability at 125°C is given by:

For VSSOP package (dual channel):

Equation 8.

P_{D (Max) = \frac{150 ° C - 125 ° C}{169.6 ° C} = 0.147 W}

For SOIC package (single channel):

Equation 9.

P_{D (Max) = \frac{150 ° C - 125 ° C}{124 ° C} = 0.202 W}

When high power is required and ambient temperature can't be reduced, providing air flow is an effective approach to reduce thermal resistance therefore to improve power capability.