Control circuit, control method and primary-controlled flyback converter using the same
AssigneeSilergy Semiconductor Technology (Hangzhou) LTD
InventorsHuiqiang Chen, Jianxin Wang
Life of this patent
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Abstract
In one embodiment, a control circuit configured to control a power stage circuit of a primary-controlled flyback converter, can include: (i) a current sense circuit that generates a current sense signal by sampling a primary current; (ii) a voltage sense circuit that generates a voltage sense signal by sampling an auxiliary voltage after a blanking time has elapsed; (iii) a control signal generator that generates a switch control signal according to the voltage sense signal and the current sense signal; and (iv) the switch control signal being configured to control a power switch of the power stage circuit, where the switch control signal is active during a constant on time.
Claims13
A control circuit configured to control a power stage circuit of a primary-controlled flyback converter, the control circuit comprising:
- a) a current sense circuit configured to generate a current sense signal by sampling a primary current;
- b) a voltage sense circuit configured to generate a voltage sense signal by sampling an auxiliary voltage after a blanking time has elapsed;
- c) a control signal generator configured to generate a switch control signal according to said voltage sense signal and said current sense signal, wherein said control signal generator generates said switch control signal under a constant on time mode when said current sense signal is greater than a current threshold after a constant on time, and wherein said control signal generator generates said switch control signal under a peak current mode when said current sense signal is less than said current threshold after said constant on time;
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- d) said switch control signal being configured to control a power switch of said power stage circuit, wherein said switch control signal is active during said constant on time.
A control circuit configured to control a power stage circuit of a primary-controlled flyback converter, the control circuit comprising:
- a) a current sense circuit configured to generate a current sense signal by sampling a primary current;
- b) a voltage sense circuit configured to generate a voltage sense signal by sampling an auxiliary voltage after a blanking time has elapsed, wherein said blanking time changes along with a peak of said current sense signal;
- c) a control signal generator configured to generate a switch control signal with a constant on time according to said voltage sense signal;
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- d) said switch control signal being configured to control a power switch of said power stage circuit.
A method of controlling a power stage circuit of a primary-controlled flyback converter, the method comprising:
- a) generating a current sense signal by sampling a primary current;
- b) generating a voltage sense signal by sampling an auxiliary voltage after a blanking time has elapsed;
- c) controlling a power switch of said primary-controlled flyback converter according to said voltage sense signal and said current sense signal, wherein said controlling said power switch comprises controlling under a constant on time control mode when said current sense signal is greater than a current threshold after a constant on time, and controlling said power switch under a peak current control mode when said current sense signal is less than said current threshold after said constant on time;
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- d) maintaining said switch control signal as active during said constant on time.
Dependencies are inferred from the claim text.