Power management for USB2.0 5V supply using load resistive and switch capacitive detection approach

In this paper, two proposed power management circuitries for USB 5V supply are demonstrated by using the current sense amplifier and switches architecture. The design architecture was simulated by using the LTspice tools. There are some power losses in the switched-mode power supply (SMPS) when supplying 5V to the USB port in board level design. The Cedar board will be used as a reference board throughout this work. The total amount of losses in Cedar 5V SMPS is measured and calculated which consumes 21mW. Two proposed detection circuitries which are load resistive and switch capacitive are used to save the power losses in SMPS. The simulation results for the power consumption of load resistive approach consume 2mW whereas for switch capacitive approach consumes 7.5mW when the 5V SMPS is switched off. The results show that the load resistive and switch capacitive approaches will save total amount of 19mW and 13.5mW respectively in the Cedar board design. The load resistive approach has been implemented using breadboard and printed circuit board (PCB) and the power consumption when the 5V SMPS is switched off is measured which consumes 2.536mW. The total power saving is 18.5mW. The performance of this design is optimum for USB2.0 current from 10mA to 200mA for achieving the low power purpose.