9.1 Power Dissipation

The LMH6574 is optimized for maximum speed and performance in the small form factor of the standard SOIC package. To ensure maximum output drive and highest performance, thermal shutdown is not provided. Therefore, it is of utmost importance to make sure that the T_JMAX is never exceeded due to the overall power dissipation.

Follow these steps to determine the Maximum power dissipation for the LMH6574:

1. Calculate the quiescent (no-load) power.
Equation 1. P_AMP = I_CC* (V_S)
where
• V_S = V⁺ - V⁻
2. Calculate the RMS power dissipated in the output stage:
Equation 2. P_D (rms) = rms ((V_S - V_OUT) * I_OUT)
where
• V_OUT is the voltage across the external load
• I_OUT is the current through the external load
• V_S is the total supply voltage
3. Calculate the total RMS power: P_T = P_AMP + P_D.

The maximum power that the LMH6574 package can dissipate at a given temperature can be derived with the following equation:

For the SOIC package R_θJA is 130 °C/W.