the 7805 is not a low drop out regulator. In otherwords, you need ~ 1.5 or 2V higher input to maintain 5V output regulation. Input 7V and see what you get on output.
the 7805 is not a low drop out regulator. In otherwords, you need ~ 1.5 or 2V higher input to maintain 5V output regulation. Input 7V and see what you get on output.
If it's fairly low (<50mA) then I'd go for the LM2936-5 which has a droput voltage of just 200mV so it'll give 5V until the battery drops to just 5.2V and most 5V stuff will still work at around 4V meaning that it'll still work when the battery drops to 4.7V.
That's true, I suppose it depends on the current draw and the minimum voltage requirements of the circuit.. I have as multimeter that won't even work properly at 7.2V, it displays the low battery symbol which isn't any good when run of a 7.2V battery.
A 9V alkaline battery works for years in my Fluke multimeter.
My cheap Chinese multimeter also works for a long time on a 9V alkaline battery but it doesn't automatically turn itself off. I must remember to turn it off.
use a TPS61040 from texas instruments, 1.8 to 3v in, 5v out, 400mA max. There are chips that'll go lower in voltage, or provide more current, but the tps is easy to use and at 1mhz, needs only small passive components to get the job done.
There is another boost regulator from TI, TPS61200 which has the input voltage range of 0.3 V - 5.5 V with the output voltage adjustable up to 5 V. The max output current is 600 mA.
But the SON package makes me cry while doing soldering T_T