Energy storage power supply emc rectification

Can a synchronous rectifier reduce power loss?

Today it is well known that using a synchronous rectifier can reduce power loss and improve thermal capability. Designers of buck converters and controllers for step-down applications are already employing this technique. Synchronous boost controllers also have been developed to address power efficiency in step-up applications.

How does a synchronous rectifier work?

With a synchronous rectifier, there are two main sources of power dissipation—conduction and dead-time loss. When the low-side switch turns off, there is a time delay (tDELAY) before the high-side switch turns on. During this delay, the body diode (VSD) of the high-side switch con-ducts current. Typically this is referred to as dead time.

Why do synchronous rectifiers depend on duty cycle for power dissipation?

With a synchronous rectifier, there is some dependence on the duty cycle for power dissipation because the conduction losses are caused by the resistance of the FET. This is unlike a diode, where the losses are caused by the forward voltage drop.

How does a DC/DC power supply work?

The DC/DC power supply steps up the voltage for charging a two-cell Li-Ion battery or the battery of a tablet PC. The other application boosts the voltage of a system power rail to a high output voltage that can operate at higher duty cycles where the output voltage is much higher than the input voltage. An example input is a 12-V power rail.

How much space does a synchronous power block switch occupy?

A comparison of solution sizes based only on typical switch package sizes finds that the nonsynchronous switch and diode occupy an area of 65 mm2, and the synchronous power-block switches occupy an area of 12 mm2. The latter is a space savings of 53 mm2. Both designs use the same LC filter and a 750-kHz switching frequency.