Linear Regulator (LDO) Power Dissipation Calculator

This tool calculates the power dissipation of a linear voltage regulator.

Enter

  • Input Voltage
  • Output Voltage
  • Output Current
  • Quiescent (or Ground) Current

	

			

		

						

				

				

                

			

			
						

		

		











Formula





 P = (VIN – VOUT) * IOUT + VIN * IQ





Background





The power dissipation of a linear regulator is a function of the voltage differential between the input and output and the current drawn by the load, The quiescent current is typically small (less than 1 mA) and as a result it does not contribute in a significant way.





The larger the difference between the input and output voltage, the greater the power dissipation. 





Example Calculation





If the linear regulator converts 5V to 3.3V with an output current of 150 mA and quiescent current of 250 uA, the power dissipation is 256 mW.





If the input voltage is increased to 12V, the dissipation increases to 1.3 Watt. 





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