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Low Vce sat BJT Power Savings Slide 6

This schematic shows a typical charging circuit with the 5.0V input derived from a wall adapter. In this circuit the MOSFET requires a Schottky diode to prevent reverse current flow. However, the Schottky diode creates a significant power loss. 1.0A current will be used for calculation purposes, thus making it easy to derive power. At 1.0A the MOSFET has an RDS(on) of 60mΏ, the Schottky diode has a forward drop of 360mV. This results in a total power dissipation through these two devices of 420mW.

PTM Published on: 2011-12-07