Hi,
My circuit below is a simple car voltage step down to from by car's 12v (or 13.7v) to 5v USB output on the dash.
Now I want to take some load off the LM7805 so it doesn't heat up as much (or require such a large heatsink).
According to my circuit simulation I can give it input of 8.6v instead of 13.7 using a 5ohm high power resistor:
Does anyone know if this is a good idea do include this resistor (R1).
My main goal is to make the LM7805 not work as hard and disipate so much heat.
As the dummy 5v bulb load suggests, I will only ever be pulling 1000mA at 5v from the 7805's output, so input voltage will never drop below 8.6v.
My circuit below is a simple car voltage step down to from by car's 12v (or 13.7v) to 5v USB output on the dash.
Now I want to take some load off the LM7805 so it doesn't heat up as much (or require such a large heatsink).
According to my circuit simulation I can give it input of 8.6v instead of 13.7 using a 5ohm high power resistor:
Does anyone know if this is a good idea do include this resistor (R1).
My main goal is to make the LM7805 not work as hard and disipate so much heat.
As the dummy 5v bulb load suggests, I will only ever be pulling 1000mA at 5v from the 7805's output, so input voltage will never drop below 8.6v.