# Doubt on the Voltage Regulator Application with LiPo Battery

If I have a LiPo battery with the maximum voltage of 12V and I want to use it to power a 5v(L7805) voltage regulator. Assuming the maximum current passing through the regulator is 500mA. From datasheet, the thermal resistance is 50°C/W.

Does that mean that it would generate a power loss of 3.5W and it would raise the voltage regulator's temperature by 175°C? The maximum operating temperature of the voltage regulator is 150°C. Would that means I need to drop the input voltage of the regulator?

I am not able to get a switching regulator and the great power loss is not a concern. Would the thing work if I stack multiple voltage regulator together?

• That's exactly what it means. Alternatively, you could use a heatsink. But keep in mind that all that power is just being wasted--you should look into a switching regulator, not a linear one, for this level of voltage difference and current. Commented May 8, 2017 at 14:56
• If I am not able to get a switching regulator and the great power loss is not a concerned. Would the thing work if I stack multiple voltage regulator together? I did some rough calculation. If I am constructing the circuit without using resistor, using four voltage regulator would raise each temperature by 90°C. Commented May 8, 2017 at 15:07
• Remember that heatsinks are an option as well. With a heatsink, you can reduce the case-to-ambient thermal resistance. Commented May 8, 2017 at 15:10
• Have you calculated the maximum value of a series resistor between 12V and the regulator? And what would the worst case regulator and resistor power be? Commented May 8, 2017 at 15:16
• By the way, if I use heatsink instead of resistor to handle to power loss. It would give me a larger allowance on the battery voltage drop, right? Commented May 8, 2017 at 15:21