View ba9700a datasheet:

BA9700A / BA9700AF / BA9700AFV Regulator ICs Switching regulator for DC / DC Converters BA9700A / BA9700AF / BA9700AFV The BA9700A, BA9700AF and BA9700AFV are switching regulators that use a pulse width modulation (PWM) system. They use a transistor switch to stabilize the output voltage. By the use of the transistor, power loss is decreased, fluctuation efficiency is improved, and the circuit is made more compact and single. Features 1) Output voltage can step up, step down, or invert at an 6) Dead time controller restricts operation when arbitrary level. overloaded. 2) Low current consumption. (typically 1.7mA) 7) Power switch can isolate all circuits in the IC. 3) Wide oscillation frequency range. 8) Best suited for battery operated equipment. (typically 2.8k ~ 470kHz) 9