( In reference to thread: http://forum.allaboutcircuits.com/showthread.php?t=80117&page=2 )
First proto (Apart from the whole power circuitry being wrong) the LM7805 1.5A VREG gets rather hot, so much so that I've raised it to stand vertical and put a heatsink on it.
Still gets too hot.
That's with a 9V 2A DC SM PSU feeding it, with either the RPI connected (~400mA draw), or every relay engaged (~450mA). Have not been keen to try both.
Is there something I'm doing wrong? Should the LM7805 get that hot at < 1A load?
What is the "Temperature coefficient of output voltage" listed in the LM7805 datasheet?
Should I be looking at voltage "conversion" rather than "regulation" ie. DC to DC power supply rather than a wide range DC input in to a 5V vreg?
PCB space is minimal, I need somewhere between 1.5 to 3A @ 5V - Ideas?
First proto (Apart from the whole power circuitry being wrong) the LM7805 1.5A VREG gets rather hot, so much so that I've raised it to stand vertical and put a heatsink on it.
Still gets too hot.
That's with a 9V 2A DC SM PSU feeding it, with either the RPI connected (~400mA draw), or every relay engaged (~450mA). Have not been keen to try both.
Is there something I'm doing wrong? Should the LM7805 get that hot at < 1A load?
What is the "Temperature coefficient of output voltage" listed in the LM7805 datasheet?
Should I be looking at voltage "conversion" rather than "regulation" ie. DC to DC power supply rather than a wide range DC input in to a 5V vreg?
PCB space is minimal, I need somewhere between 1.5 to 3A @ 5V - Ideas?