ECG 497/498

Homework #1

Print this page, write in your answers (showing some work), and hand in Fri, Sept. 17.



1)  Estimate the temperature rise above ambient for the following 5V regulator (with out a heatsink in still air).  The load current is 100mA and the input voltage is 15V (Hint: use the Thermal Resistance Junction-Air).  You may neglect the regulators quiescent current when calculating the power dissipation.











2)  Estimate the temperature rise above ambient (same input and load) if the following heat sink was attached the regulator (still no airflow, Hint: use the Thermal Resistance Junction-Case + Thermal Resistance of the Heatsink).











3)  Estimate the temperature rise if a fan was blowing 300ft/min of air across the heatsink (every thing else is the same, Hint: use the graph to find the new value for the Thermal Resistance of the heat sink).