1. What is Light Load Mode?
Light load mode is a technique for improving efficiency when using less output current. In DC-DC converters, it's also called pulse train mode.Switching AC/DC and DC-DC converters use ON/OFF switching for voltage chopping and capacitor smoothing to stably provide the target output voltage.
2.Why does the converter struggle under light load?
Every time the circuit changes state the circuit creates an extra current. This extra current does not do anything for the circuit. It just gets turned into heat for the circuit.
When this happens a lot, in one second it wastes energy and the circuit does not work as well as it should. The circuit becomes less efficient because this happens often per second. The more this happens per second the more energy the circuit wastes.
3.How can high efficiency and energy savings be achieved in light-load mode?
With constant period (PWM control), even if the ON/OFF time ratio changes, the number of cycles remains constant per unit time.Therefore, the power consumption is also constant. Under light load, the leakage current loss during these transitions leads to reduced efficiency. Therefore, when using low current, frequency modulation (PFM control) is used to lengthen and slow down the period, thereby reducing the number of ON/OFF transitions per unit time and minimizing losses. This technique is called light load mode.
In summary, light-load mode is a smart energy-saving strategy for DC converters in low-power scenarios. By switching from fixed-frequency PWM control to variable-frequency PFM control, it significantly reduces the number of switching operations per unit of time, fundamentally lowering switching and driving losses, and preventing valuable energy from being unnecessarily converted into heat.This technology allows electronic devices to greatly improve energy efficiency and extend battery life, whether they are in standby, sleep mode, or merely performing background tasks.
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