Pulse-width modulation (PWM) switching power supply, frequency jitter circuit thereof and frequency jitter method

Abstract

The invention discloses a pulse-width modulation (PWM) switching power supply, a frequency jitter circuit thereof and a frequency jitter method, wherein the frequency jitter circuit comprises a frequency jitter module, wherein the frequency jitter module is connected with a primary side peak current detection comparator of the switching power supply for improving the reference voltage of the primary side peak current detection comparator, so the primary side peak current of the primary side peak current detection comparator is changed, and the switching frequency of the switching power supply is jittered. Through changing the reference voltage of the primary side peak current detection comparator to change the primary side peak current, the switching frequency of the switching power supply is jittered. The variation range of the primary side peak current is controlled through setting the variation range of the reference voltage, so the frequency jitter range of the switching power supply can be controlled, the switching frequency of the switching power supply which adopts the frequency jitter circuit can be controlled to periodically jitter, and accordingly, the switching power supply has better electromagnetic compatibility.

Description

Technical field [0001] The invention relates to the technical field of integrated circuit manufacturing technology, and more specifically, to a PFM switching power supply and a frequency jitter circuit and a frequency jitter method thereof. Background technique [0002] Switching power supply is a circuit device that uses modern power electronic technology to control the time ratio of switching on and off to maintain a stable output. Among them, a common switching power supply is a pulse frequency modulation (PFM) switching power supply with a constant current and constant voltage working mode, that is, the switching power supply controls the on and off of the switching tube through PFM to maintain a stable output, so that the entire The switching power supply system works in constant voltage or constant current mode. PFM switching power supply has a high rate of voltage change and current change, and its transformer has parasitic capacitance and parasitic inductance, which form...

AI Technical Summary

Problems solved by technology

However, the charging voltage of the charge pump is not easy to control, ie image 3 The step width of the stepped dotted line shown in can not be controlled, which makes it difficult to control the range of frequency jitter based on the above mechanism, resulting in poor electromagnetic compatibility of the switching power supply

[0008] Through the above analysis, it can be seen that the existing technology can only realize the switching frequency jitter of the PFM switching power supply at some load points, and its frequency jitter is not easy to control, and the electromagnetic compatibility of the switching power supply is poor.

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