Enter the Refractive Indices and Angle of Incidence into the Snell's Law Calculator to find the Refraction Angle, Critical Angle, Total Internal Reflection status, and Light Speed in each medium.
Power Dissipation
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Output Voltage
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Junction Temperature
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Efficiency
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Dropout Voltage
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Heatsink Required
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The LM7805 requires a minimum input voltage of 7V (2V above the 5V output) for proper regulation. Higher input voltages increase power dissipation and heat generation.
Power dissipation is calculated using P = (Vin - Vout) × Iload. For example, with 12V input, 5V output, and 100mA load: P = (12-5) × 0.1 = 0.7W.
A heatsink is needed when power dissipation exceeds the regulator's thermal limits without one. Generally, if power dissipation is over 1W or junction temperature exceeds 125°C, use a heatsink.
The LM7805 can handle up to 1.5A of output current with proper thermal management. Current capability decreases with higher ambient temperatures and power dissipation.
High heat indicates excessive power dissipation due to large voltage difference between input and output, high load current, or inadequate cooling. Consider using a switching regulator for better efficiency.
Exceeding maximum junction temperature (125°C for 78xx series) triggers thermal shutdown protection. The regulator stops working until it cools down, potentially causing system instability.
Yes, the LM7805 works well at low currents. However, quiescent current (4-8mA) becomes significant relative to load current, reducing overall efficiency for very light loads.
The 78xx series differs only in output voltage: 7805 outputs 5V, 7812 outputs 12V, etc. All have similar current ratings, thermal characteristics, and dropout voltages.