Linear Technology Corporation

Linear Technology Holding LLC

Michael Thomas Engelhardt

Leonard Shtargot

Randy Guy Flatness

A switch mode power supply may utilize a switching signal to control one or more power switches in the switch mode power supply. A switch mode power supply controller may generate and/or control this switching signal. The controller may reduce the peak spectral noise of the switch mode power supply by varying the instantaneous switching frequency at a constant slew rate magnitude that changes sign at random times. The instantaneous switching frequency may be controlled by a signal that is generated by integrating a random bit stream. The stream may repeat at a sub-audio frequency. The integrator may be lossy, so that the output does not wonder off to an arbitrary value. The frequency modulation signal may be filtered by a low pass filter.

Spread spectrum for switch mode power supplies

A predicted ripple in the feedback voltage of a switching converter is generated, based on the ripple over a certain number of recent switching cycles. The DC portion of the feedback voltage is filtered out. This predicted feedback voltage ripple is then added to a fixed reference voltage to create a compensated reference voltage. The compensated reference voltage is applied to the non-inverting input of an error amplifier, and the feedback voltage (having a DC component and ripple) is applied to the inverting input of the error amplifier. Thus, substantially the same ripple component is applied to both inputs and cancels out. Therefore, the output of the error amplifier is not affected by the ripple in the feedback voltage, and a non-rippling control voltage is generated by the error amplifier. As a result, the gain-bandwidth product of the converter can be increased for faster response to transients.

Predictive ripple-cancelling signal into error amplifier of switch mode power supply

A method and system of providing an active differential resistor. The active differential resistor includes a diode having a first node and a second node. There is a capacitor coupled in series between the first node of the diode and an input of the active differential resistor. There is a current source coupled across the first node and the second node of the diode and configured to forward bias the diode such that a Johnson-Nyquist noise of the active differential resistor is replaced by a shot noise.

Active differential resistors with reduced noise

Generated are an error signal representative of a difference between a signal representative of the output voltage of a current mode switching power supply and a reference voltage, and a peak current threshold signal that is indicative of a peak current that should be reached in an inductor within the power supply during each cycle of a periodic clock signal and that has a level that is based on the error signal. A switch control signal regulates the voltage output of the power supply by closing and then opening a power switch during each cycle of the periodic clock signal. Timing of opening is based on the peak current threshold signal. Negative slope compensation causes the switch control circuit to delay opening the power switch during each cycle of the periodic clock signal in an amount that decreases with increasing duty cycles of the switch control signal.

Negative slope compensation for current mode switching power supply

A power supply system has an inductive device, a plurality of switching devices for providing connection of the inductive device to input and output nodes and a ground node, and a switch driver circuit for driving the switching devices so as to enable the power supply to operate in a boost mode to increase the input voltage, in a buck mode to decrease the input voltage, and in a solid-state flyback mode to transfer between the boost mode and the buck mode. In the solid-state flyback mode, the switching devices are controlled to provide switching of the inductive device between an input state in which the inductive device is connected between the input node and the ground node, and an output state in which the inductive device is connected between the ground node and the output node.

Switch mode power supply with dynamic topology

The present disclosure relates to simulating inductors wound on a ferromagnetic core as the magnetic material saturates. In one application, the present disclosure is advantageously used to model the asymmetric minor hysteresis loops commonly traversed by the output inductor of a switch mode power supply. An advantage of the subject matter of the disclosure is that it allows practical nonlinear inductors to be modeled in a computationally lightweight manner without conventional non-physical behavior under asymmetric minor hysteresis loop traversals. The disclosure is also conveniently applicable to practical ferromagnetic core materials because, in one particular implementation, the input parameters to the model are the core's coercive force (Hc), remnant magnetization flux density (Br), and saturation flux density (Bs).

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Sunnyvale, CA, United States of America

Michael Thomas Engelhardt