DC/DC Converter Application Note
Generally, the input and output of the step-up DC/DC converter using diode rectifier are connected through an inductor and a diode, as shown in the RP401x. Therefore, the device outputs the voltage almost equal to the power supply voltage even during standby mode. To reduce the output voltage to zero, it is necessary to add FETs to shut down the input voltage. However, Ricoh’s step-up DC/DC converter, as shown in the RP402x, uses a built-in FET instead of using a diode to enable shutdown function.
The R1200x/ R1202x use built-in NPN transistors instead of using diodes to enable shutdown function.
The R1213K uses an external Pch MOSFET controlled by the FLAG pin to enable shutdown function.