10.3 Power Dissipation and Thermal Considerations

Calculate power dissipated in the device using Equation 4.
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Equation 4.

where:

P_D = continuous power dissipation
I_O = output current
V_IN = input voltage
V_OUT = output voltage

As I_(q)<< I_O, therefore ignore the term I_(q) × V_IN in Equation 4.

For a device under operation at a given ambient air temperature (T_A), calculate the junction temperature (T_J) using Equation 5.
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Equation 5.

where:

R_θJA = junction-to-ambient air thermal impedance

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Equation 6.