This document describes a reliable USB modem design using the combination of an integrated load switch and a buck converter. By using this design, the power management issues caused by the high current requirements of GSM and GPRS wireless modems can be addressed.
This document details a power management solution for GSM and GPRS wireless modems powered by a USB source. It addresses the challenge of providing up to 2A peak current while limiting input current to 600mA to protect the USB hub. The design utilizes the FPF2195 IntelliMAX load switch for input over-current protection and the FAN8060 synchronous step-down converter for efficient power delivery.
| FPF2195 Current Limit Range | 0.15 to 1.5A |
|---|---|
| FPF2195 Conductive Resistance | 44mΩ at 5V |
| FPF2195 Thermal Shutdown | 140°C |
| FAN8060 Switching Frequency | 1.2MHz |
| FAN8060 Efficiency | 95% |
| GSM Peak Current Requirement | 2A |
| GSM Average Current | 340mA |
| GPRS Average Current | 570mA |
The design limits the input current to 600mA to avoid overloading the USB power source.
Both GSM and GPRS systems require up to 2A of peak current during transmission.
The output voltage decreases by 300mV during the GSM mode pulse load.