Off-line converter with integrated softstart and frequency jitter
DC CAFCFirst Claim
1. A pulse width modulated switch comprisinga first terminal;
- a second terminal;
a switch comprising a control input, the switch allowing a signal to be transmitted between said first terminal and said second terminal according to a drive signal provided at said control input;
an oscillator that provides a maximum duty cycle signal comprising an on-state and an off-state;
a drive circuit that provides said drive signal according to said maximum duty cycle signal; and
a soft start circuit that provides a signal instructing said drive circuit to disable said drive signal during at least a portion of said on-state of said maximum duty cycle.
0 Assignments
Litigations
0 Petitions
Reexamination
Accused Products
Abstract
A pulse width modulated switch comprises a first terminal, a second terminal, and a switch that allows a signal to be transmitted between the first terminal and the second terminal according to a drive signal provided at a control input. The pulse width modulated switch also comprises a frequency variation circuit that provides a frequency variation signal and an oscillator that provides an oscillation signal having a frequency of that varies within a frequency range according to the frequency variation signal. The oscillator further provides a maximum duty cycle signal comprising a first state and a second state. The pulse width modulated switch further comprises a drive circuit that provides the drive signal when the maximum duty cycle signal is in the first state and a magnitude of the oscillation signal is below a variable threshold level.
190 Citations
18 Claims
-
1. A pulse width modulated switch comprising
a first terminal; -
a second terminal;
a switch comprising a control input, the switch allowing a signal to be transmitted between said first terminal and said second terminal according to a drive signal provided at said control input;
an oscillator that provides a maximum duty cycle signal comprising an on-state and an off-state;
a drive circuit that provides said drive signal according to said maximum duty cycle signal; and
a soft start circuit that provides a signal instructing said drive circuit to disable said drive signal during at least a portion of said on-state of said maximum duty cycle. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
a comparator that provides a comparator signal when a magnitude of a reference signal is greater than or equal to a magnitude of said frequency variation oscillation signal, and an inverter that receives said comparator signal and provides said soft start signal. -
5. The pulse width modulated switch of claim 1 further comprising a frequency variation circuit that provides a frequency variation signal, wherein said oscillator provides an oscillation signal and wherein said soft start circuit provides said signal instructing said drive circuit to disable said drive signal when a magnitude of said oscillation signal is greater than a magnitude of said frequency variation signal.
-
6. The pulse width modulated switch of claim 5 wherein said oscillator comprises an input that receives said frequency signal and said oscillation signal comprises a frequency range, and wherein said frequency of said oscillation signal varies within said frequency range according to a magnitude of said frequency variation signal.
-
7. The pulse width modulated switch of claim 6 wherein said oscillator further comprises a current source, wherein said frequency of said oscillation signal is a function of a sum of a magnitude of a current provided by said current source and said magnitude of said frequency variation signal.
-
8. The pulse width modulated switch of claim 1 further comprising
a rectifier comprising a rectifier input and a rectifier output, said rectifier input receiving an AC mains signal and said rectifier output providing a rectifier signal; -
a power supply capacitor that receives said rectified signal;
a first winding comprising a first terminal and a second terminal, said first winding receiving a substantially DC signal from said power supply capacitor, said second terminal of said first winding coupled to said first terminal of said pulse width modulated switch; and
a second winding magnetically coupled to said first winding, said first winding capable of being coupled to a load.
-
-
-
9. A regulation circuit comprising
a first terminal; -
a second terminal;
a switch comprising a control input, said switch allowing a signal to be transmitted between said first terminal and said second terminal according to a drive signal provided at said control input;
a drive circuit that provides said drive signal for a maximum time period of a cycle; and
a soft start circuit that provides a signal instructing said drive circuit to disable said drive signal during at least a portion of said maximum time period. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16, 17, 18)
a comparator that provides a comparator signal when a magnitude of a reference signal is greater than or equal to a magnitude of said additional oscillation signal, and an inverter that receives said comparator signal and provides said soft start signal. -
14. The regulation circuit of claim 9 further comprising a frequency variation circuit that provides a frequency variation signal and wherein said maximum time period varies according to a magnitude of said frequency variation signal.
-
15. The regulation circuit of claim 9 further comprising a feedback terminal and wherein when a signal is received at said feedback terminal said drive signal is discontinued for at least one cycle.
-
16. The regulation circuit of claim 9 wherein said first terminal, said second terminal, said oscillator and said soft start circuit comprise a monolithic device.
-
17. The regulation circuit of claim 16 further comprising a current limit circuit that provides a signal instructing said drive circuit to discontinue said drive signal when a current received at said first terminal of said regulation circuit is above a threshold level.
-
18. The regulation circuit of claim 9 further comprising
a rectifier comprising a rectifier input and a rectifier output, said rectifier input receiving an AC mains signal and said rectifier output providing a rectifier signal; -
a power supply capacitor that receives said rectified signal;
a first winding comprising a first terminal and a second terminal, said first winding receiving a substantially DC signal from said power supply capacitor, said second terminal of said first winding coupled to said first terminal of said regulation circuit; and
a second winding magnetically coupled to said first winding, said first winding capable of being coupled to a load.
-
-
Specification