US 12,249,907 B2
Noise control circuit for a switching mode power supply and a method thereof
Shuai Wang, Hangzhou (CN); and Hui Li, Hangzhou (CN)
Assigned to Chengdu Monolithic Power Systems Co., Ltd., Sichuan (CN)
Filed by Chengdu Monolithic Power Systems Co., Ltd., Chengdu (CN)
Filed on Nov. 9, 2022, as Appl. No. 17/983,544.
Claims priority of application No. 202111438440.1 (CN), filed on Nov. 30, 2021.
Prior Publication US 2023/0170788 A1, Jun. 1, 2023
Int. Cl. H02M 3/335 (2006.01); H02M 1/14 (2006.01)
CPC H02M 1/143 (2013.01) [H02M 3/33515 (2013.01); H02M 3/33523 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A noise control circuit of a switching mode power supply, wherein the switching mode power supply has a primary switch, a secondary switch and a transformer with a primary winding, and a secondary winding having a first terminal and a second terminal, and wherein the primary switch has a first pulse terminal configured to receive a switching control signal for controlling the primary switch, and a second pulse terminal coupled to the primary winding, the noise control circuit comprising:
a reverse noise generating circuit, having a first input terminal coupled to either the first or the second pulse terminal of the primary switch, a second input terminal configured to receive an adjusting signal, and an output terminal configured to provide a noise control signal in response to the adjusting signal and a signal at the pulse terminal that the reverse noise generating circuit is coupled to;
wherein the noise control signal is coupled to either terminal of the secondary winding of the transformer; and wherein
the reverse noise generating circuit comprises:
a detecting circuit, configured to receive the adjusting signal, and to provide a first voltage regulating signal and a second voltage regulating signal in response to the adjusting signal; and
a logic circuit, having a power source terminal configured to receive the first voltage regulating signal, a ground reference terminal configured to receive the second voltage regulating signal, an input terminal configured to receive the signal at the pulse terminal that the reverse noise generating circuit is coupled to, and an output terminal configured to provide the noise control signal in response to the first voltage regulating signal, the second voltage regulating signal and the signal at the pulse terminal that the reverse noise generating circuit is coupled to.