Fixed frequency DC to DC converter control circuit with improved load transient response

Abstract

Analog pulse width modulation (PWM) control circuits and techniques are presented for improving output voltage load transient response in controlling DC to DC conversion systems in which a transient detector circuit restarts a PWM carrier ramp waveform to initiate asynchronous injection of a pulse between the regular periodic PWM pulses in a fixed frequency pulse stream to mitigate the effect of output inductor energy depletion on output voltage.

Description

[0001] Cross References to Related Applications [0002] This application claims priority and benefit to U.S. Provisional Patent Application No. 61 / 700,176, filed September 12, 2012, entitled "Improved Output Voltage Load Transient Response in Fixed Frequency DC-to-DC Converters" circuit", the entire contents of which are incorporated into this application by reference. technical field [0003] The present invention relates to the control of DC to DC converters, and in particular to fixed frequency PWM control circuits for controlling DC to DC conversion systems. Background technique [0004] Power supplies for modern electronic circuits typically need to provide a stable, regulated supply voltage for proper operation of processors, application specific integrated circuits (ASICs), memory and other components. Computers, smartphones, tablets, and other electronic products typically employ DC-to-DC converters to provide a power supply voltage for the operation of internal ci...

AI Technical Summary

Problems solved by technology

During load transients, the magnitude of the voltage dip can be addressed to some extent by adding output capacitance to obtain the required energy, but the additional capacitance value increases the cost and size of the power conversion system

In order to deal with the problem of load transient response, variable frequency PWM methods can be adopted, including fixed on-time with hysteresis, fixed off-time and other methods. They can work close to the approximate fixed frequency in some cases, but may be for Applications in systems synchronized to the system clock or in multiphase or stacked converter architectures where variable frequency designs are difficult to implement

Furthermore, the application of a hysteretic comparator providing a control loop outside the fixed frequency inner loop requires the controller to multiplex the I / O pins to monitor the output voltage and the selection of filter components to avoid loop-to-loop oscillations is controlled. Comparator usage is limited by the

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