Op amp makes precise 9V-battery splitter

Op amp makes precise 9V-battery splitter


Alkaline 9V batteries are ideal for many portable, handheld applications, because they have 650 mAhrs of capacity, operate as low as approximately 6V at the end of their lives, and are available everywhere. The trouble starts when you want to power 5V analog parts, and you need a true swing from ground to 5V. Although many op amps advertise single-supply operation, many only swing 100 mV or so to ground on the output. To generate a negative bias usually requires that you use a negative voltage converter, such as an ICL7660 charge pump