News Detail

Maximize the efficiency of power supply switching supplies

Maximize the efficiency of power supply switching supplies

Why spend time in switch mode power supplies to maximize efficiency? Higher efficiency switching regulators make you value for money. In the world of mobile devices, power consumption must be minimized and power should not be wasted.

The main source of loss
The main source of loss in the power supply switching varies with the load current. At high currents, the main source of loss is the power converted into heat by the resistance of the field effect transistor (FET) and inductor. At low currents, the main power supply will turn the FET on and off.

It is the best choice between heavy load and light load. This is where the effects of gate switching power and resistance losses are balanced and maximum efficiency is achieved. Ideally, the regulator will operate here, but this depends on the amount of current drawn by the load. In the chart provided in the converter data sheet, the nominal current consumption is compared with the current consumption to achieve peak efficiency.

Optimize FET
FET requirements will vary with each design. There is no one perfect FET for every application, but there are some key criteria that can be used to maximize efficiency. Reduce the resistance between the drain and source of the FET. After completing the arithmetic to determine the power loss, confirm that the FET or integrated circuit can effectively dissipate the power as heat. As the temperature of the semiconductor increases, the resistance will decrease.

Synchronous and asynchronous converters
Synchronous converters have built-in low-side switches that replace the rectifier diodes used in asynchronous converters. Synchronous converters are almost always more efficient than asynchronous converters. At any reasonable RDS (<50mΩ), the power burned on the diode will make the power of the low-side FET comparable.

For asynchronous converters, Schottky diodes can be a good replacement for rectifier diodes. Their forward pressure is much lower. The reverse polarity recovery time of Schottky diodes is slow, so make sure to use a frequency suitable for Schottky diodes.

Inductance factor
Just like FETs, there is power dissipation in the inductor's resistance (DCR). Choosing an inductor with a smaller DCR helps reduce power consumption. Core loss will increase with increasing switching frequency, and a higher power supply switching frequency allows the selection of physically smaller inductors.

Consult the data sheet
Many data sheets now have efficiency charts and recommended component values. Sometimes they even include the recommended part number. Manufacturers are also committed to making the most of their DC-DC converters. Although you are unlikely to see the same results in a near-ideal test environment, it is best to use them as a starting point to check your numbers.

The main ways to improve efficiency in a switch mode power supply are:
Minimize RDS of FET and DCR of inductor
Consider using a sync converter whenever possible
Determine the optimal point frequency to which the electrical induction switches
Read the data sheet and consult the manufacturer's reference design