The TPS61098x suits for low power systems very well, especially for the system which spends the most of time in sleep mode and wakes up periodically to sense or transmit signals. For this kind of application, the boost output V_(MAIN) can be used as an always-on supply for the main system, such as an MCU controller, and the LDO or load switch output V_(SUB) is used to power peripheral devices or subsystem.

As shown in Figure 9-1, the MCU can control both of the subsystem and the TPS61098x. When the system goes into sleep mode, the MCU can disable the subsystem first, and then force the TPS61098x enter into Low Power mode, where the VSUB rail is disconnected but the V_(MAIN) rail still powers the MCU with only 300 nA quiescent current. When the system wakes up, the MCU pulls the MODE pin of TPS61098x high first to turn on the VSUB rail, and then enables the subsystem. In this way, the system can benefit both of the enhanced transient response performance in active mode and the ultra-low quiescent current in sleep mode.

Figure 9-1 Typical Application of TPS610981 to Power Low Power System