If only one power supply is needed for the whole system, users can easily leave the VSUB pin float and only use the VMAIN rail as the power supply. In this case, the TPS61098x functions as a standard boost converter. If enhanced load transient performance is needed when the system works in Active mode, the controller can control the MODE pin to switch the TPS61098x between the Active mode and Low Power mode. If the ultra-low Iq is critical for the application, users can connect the MODE pin to GND so the TPS61098x keeps working in Low Power mode with only 300 nA quiescent current. Below shows a typical application where the TPS61098 is used in Low Power mode to generate 2.2 V with only 300 nA Iq to power the whole system.

Figure 9-25 Typical Application of TPS61098 VMAIN to Power the System in Low Power Mode