Apparatus and method for monotonic start up of a synchronous switching regulator
First Claim
1. A circuit for regulation, comprising:
- a pulse modulation circuit that is arranged to provide a pulse modulation output signal based, in part, on an output signal; and
a synchronous switch control circuit that is arranged to provide a synchronous switch control signal such that the synchronous switch control signal is based, in part, on the pulse modulation output signal;
assertion of the synchronous switch control signal is disabled, substantially during a discontinuous conduction mode associated with a switch node current at a switch node; and
such that the assertion of the synchronous switch control signal is enabled, substantially during a continuous conduction mode associated with the switch node current, wherein the pulse modulation circuit and the synchronous switch control circuit are configured to operate with a first switch circuit and a synchronous switch circuit coupled together at the switch node to enable regulation of the output signal.
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Accused Products
Abstract
A controller for a synchronous switching regulator is arranged to control a switch with a control signal, and to control a synchronous switch with a synchronous switch control signal. The controller disables the synchronous switch control signal at power-up so that the regulator operates with asynchronous rectification. Also, the controller is arranged to detect whether the regulator is in discontinuous or continuous conduction mode by determining whether a switch node voltage at the switch node a switch node stays negative. The regulator keeps operating with asynchronous rectification until the switch node voltage stays negative for the entire off period of the switch, which indicates the regulator is operating in continuous conduction mode. At this point, the controller enables assertion of the synchronous switch control signal, so that the regulator operates with synchronous rectification. The controller is arranged to enable the output voltage to rise monotonically when driving a prebiased load.
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Citations
20 Claims
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1. A circuit for regulation, comprising:
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a pulse modulation circuit that is arranged to provide a pulse modulation output signal based, in part, on an output signal; and a synchronous switch control circuit that is arranged to provide a synchronous switch control signal such that the synchronous switch control signal is based, in part, on the pulse modulation output signal;
assertion of the synchronous switch control signal is disabled, substantially during a discontinuous conduction mode associated with a switch node current at a switch node; and
such that the assertion of the synchronous switch control signal is enabled, substantially during a continuous conduction mode associated with the switch node current, wherein the pulse modulation circuit and the synchronous switch control circuit are configured to operate with a first switch circuit and a synchronous switch circuit coupled together at the switch node to enable regulation of the output signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A circuit for regulation, comprising:
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a comparator circuit that is arranged to compare a comparison input voltage that is associated with a voltage at a switch node to a ground voltage; and a synchronous switch logic circuit that is arranged to provide a synchronous switch control signal to a control input of a synchronous switch circuit such that the synchronous control signal is based, in part, on an output signal; and
further based, in part, on the comparison, wherein the comparator circuit and the synchronous switch circuit are configured to operate with a first switch circuit and the synchronous switch circuit coupled together at the switch node to enable regulation of the output signal. - View Dependent Claims (10, 11, 12, 13)
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14. A method for starting up a synchronous switching regulator, comprising:
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when the synchronous switching regulator is powered up, disabling an assertion of a synchronous switch control signal, wherein the synchronous switch control signal is employed to control a synchronous switch of the synchronous switching regulator; determining whether the synchronous switching regulator is operating in continuous conduction mode; and if the synchronous switching regulator is operating in continuous conduction mode, enabling the assertion of the synchronous switch control signal. - View Dependent Claims (15, 16, 17, 18, 19, 20)
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Specification