What Are the Causes of a Low Pulse Rate?

Pulse frequency modulation (PFM) is a conversion method that is commonly used in DC-DC converters to improve light load efficiency. In the product specifications provided by TI, PFM is also called "power saving" mode. Converters operating in power saving mode use PFM mode under light load current conditions and pulse width modulation (PWM) mode under heavy load current conditions. This mode of operation allows the converter to maintain extremely high efficiency over a wide current output range.

Pulse frequency modulation

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Pulse frequency modulation (PFM) is a conversion method commonly used in

Pulse frequency modulation: English is called Pulse frequency modulation, and its abbreviation is PFM. A kind

Pulse frequency modulation (PFM) method has

One of the main reasons why pulse frequency modulation (PFM) is applied without pulse width modulation (PWM) is that the pulse width modulation (PWM) control method is easy to implement, and the pulse frequency modulation (PFM) control method is not easy to implement.

Pulse frequency modulation advantages

Compared with pulse width modulation (PWM), the main advantages of pulse frequency modulation (PFM) are efficiency:

1. For the pulse frequency modulation (PFM) and pulse width modulation (PWM) of the same peripheral circuit, the peak efficiency PFM is equivalent to PWM, but before the peak efficiency, the efficiency of pulse frequency modulation (PFM) is much higher than the pulse The efficiency of width modulation (PWM), which is the main advantage of pulse frequency modulation (PFM).

2. Pulse width modulation (PWM) The loop gain and response speed are limited due to the influence of the error amplifier. Pulse frequency modulation (PFM) has a faster response speed.

Disadvantages of pulse frequency modulation

The main disadvantage of pulse frequency modulation (PFM) compared to pulse width modulation (PWM) is that it is difficult to filter

1. Filtering is difficult (the harmonic spectrum is too wide).

2. Prior to peak efficiency, the frequency of pulse frequency modulation (PFM) was lower than the frequency of pulse width modulation (PWM), which would cause the output ripple to be larger than that of pulse width modulation (PWM).

3. The pulse frequency modulation (PFM) control is more expensive than the pulse width modulation (PWM) control IC.