JAJSGA2F September 2018 – June 2021 TPS2663
Applications having two energy sources such as Portable battery powered equipment require preference of one source to another. For example, mains power (wall-adapter) has the priority over the internal back-up power or auxiliary power. These applications demand for switch over from mains power to backup power only when main input voltage falls below a user defined threshold. The TPS2663x devices provide a simple solution for priority power multiplexing needs.
Figure 10-12 shows a typical priority power multiplexing implementation using devices. When the MAIN power is present, the device in VIN_MAIN path powers the OUT bus irrespective of whether auxiliary power VIN_AUX is greater than or less than VIN_MAIN. Once the voltage on the VIN_MAIN rail falls below the user-defined threshold, the device VIN_MAIN issues a signal to switch over to auxiliary power VIN_AUX. The transition happens seamlessly in tOVP(dly_fast), with minimal voltage droop on the output. The voltage droop during transition is a function of load current and output capacitance. See Equation 13.