Jitter frequency control circuit and control method

Abstract

The invention discloses a jitter frequency control circuit which comprises a detection module and an enabling module. The jitter frequency control circuit decides whether to be added with a jitter frequency function by detecting a pin state. Correspondingly, the invention further discloses a jitter frequency control method. The control circuit disclosed by the invention is simple in structure, convenient to use and high in integration; and an application engineer can select whether to adopt the jitter frequency function only by increasing or decreasing one peripheral component (such as a capacitor), so that the design difficulty of the application engineer is reduced, and design steps are simplified.

Description

technical field [0001] The invention relates to the field of electromagnetic technology, in particular to a frequency shaking control circuit and a control method. Background technique [0002] Now, more and more switching power supply manufacturers use frequency shaking technology to reduce electromagnetic interference (EMI). Frequency jittering technology makes the radiated energy distributed in a wide frequency range by properly modulating the switching frequency, and reduces the harmonic amplitude to make it smooth, thereby reducing EMI. [0003] However, frequency shaking technology is not only advantages without disadvantages. In some application environments, such as low-power and small-volume applications, due to the small output capacitor, frequency shaking technology often brings unbearable output ripple; In some communication power supply standards, it is clearly required that frequency shaking technology cannot be used. Therefore, in such applications, chips int...

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Problems solved by technology

[0003] However, frequency shaking technology is not only advantages without disadvantages. In some application environments, such as low-power and small-volume applications, due to the small output capacitor, frequency shaking technology often brings unbearable output ripple; In some communication power supply standards, it is clearly required that frequency shaking technology cannot be used. Therefore, in such applications, chips integrated with frequency shaking technology are often discarded, and ordinary chips are used for PWM control, which limits the use of integrated frequency shaking functions. Chip application range

[0004] On the basis of the existing technology, in order to meet the two application requirements that require frequency shaking and those that do not require frequency shaking, chip designers have to design two types of chips separately, or add additional pins as enabling pins for frequency shaking. Doing so will undoubtedly increase the design and manufacturing costs of chip design manufacturers; and for chip application manufacturers, in order to meet the above two different application requirements, they have to use two types of chips to develop two different solutions to increase the number of applications. The cost of the manufacturer's product design and product management, or separately design the peripheral enable circuit for the extra enable pin, this peripheral enable circuit is often more complicated, which will increase the design difficulty and PCB layout area

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