Control circuits and methods for voltage converters

Abstract

Control circuits and methods for voltage converters. In some embodiments, a control system or circuit can be implemented for a voltage converter, and can include a driving unit configured to generate a driving signal having a pulse width and a frequency. The driving signal can be provided to a voltage conversion circuit to control conversion of an input voltage into an output voltage. The control system or circuit can further include a modulation unit configured to modulate the pulse width of the driving signal based on the output voltage to thereby allow adjustment of the output voltage. The control system or circuit can further include a frequency control unit configured to adjust the frequency of the driving signal based on the modulated pulse width.

1 . A control system for a voltage converter, comprising:
 a driving unit configured to generate a driving signal that includes a plurality of pulses, each pulse having a width, the driving signal being provided to a voltage conversion circuit to control conversion of an input voltage into an output voltage;   a modulation unit configured to modulate the width of at least some of the pulses of the driving signal with a pulse width indication signal that is based on the output voltage to thereby allow adjustment of the output voltage; and   a frequency control unit configured to generate a frequency control signal based on the pulse with indication signal, the frequency control signal configured to adjust a frequency of the driving signal.   
     
     
         2 . The control system of  claim 1  further comprising a frequency generator configured receive the frequency control signal and decrease or increase the frequency of the driving signal. 
     
     
         3 . The control system of  claim 1  wherein the frequency control unit includes a detector configured to receive the pulse width indication signal and compare it to first and second threshold pulses having widths representative of lower and upper limits of a selected range, respectively. 
     
     
         4 . The control system of  claim 3  wherein frequency control signal is configured to provide a decrease in the frequency of the driving signal when the pulse width indication signal indicates that the modulated pulse width is less than the first threshold pulse width. 
     
     
         5 . The control system of  claim 4  wherein the decrease in the frequency of the driving signal allows a duty ratio of the voltage conversion circuit to be decreased without further decrease in the modulated pulse width below the first threshold pulse width. 
     
     
         6 . The control system of  claim 5  wherein the first threshold pulse width is selected to be greater than a minimum turn-on time of the voltage conversion circuit. 
     
     
         7 . The control system of  claim 5  wherein the first threshold pulse width is selected relative to a minimum turn-on time of the voltage conversion circuit to allow regulation of the output voltage when the output voltage is close to the input voltage or when a load driven by the output voltage is relatively low. 
     
     
         8 . The control system of  claim 3  wherein the frequency control signal is configured to provide an increase in the frequency of the driving signal when the pulse width indication signal indicates that the modulated pulse width is greater than the second threshold pulse width. 
     
     
         9 . The control system of  claim 8  wherein the increase in the frequency of the driving signal allows a duty ratio of the voltage conversion circuit to be increased beyond an increase provided by an increase in the modulated pulse width alone. 
     
     
         10 . The control system of  claim 1  wherein the detector includes a first AND gate and a second AND gate, the first AND gate generating a first output that is an AND-combination of the pulse width indication signal and the first threshold pulse, the second AND gate generating a second output that is an AND-combination of the pulse width indication signal and an inverse of the second threshold pulse. 
     
     
         11 . The control system of  claim 10  wherein the frequency control unit further includes a control signal generator having a logic circuit configured to receive the first and second outputs of the detector and generate the frequency control signal. 
     
     
         12 . A voltage converter comprising:
 a voltage conversion circuit configured to convert an input voltage into an output voltage; and   a control system configured to control the voltage conversion circuit, the control system including a driving unit configured to generate a driving signal that includes a plurality of pulses, each pulse having a width, the driving signal being provided to control the conversion of the input voltage into the output voltage, the control system further including a modulation unit configured to modulate the width of at least some of the pulses of the driving signal with a pulse width indication signal that is based on the output voltage to thereby allow adjustment of the output voltage, the control system further including a frequency control unit configured to generate a frequency control signal based on the pulse with indication signal, the frequency control signal configured to adjust a frequency of the driving signal.   
     
     
         13 . The voltage converter of  claim 12  wherein the input voltage is a DC voltage. 
     
     
         14 . The voltage converter of  claim 15  wherein voltage conversion circuit is configured such that the output voltage is less than or greater than the input voltage. 
     
     
         15 . An electronic device comprising:
 a load configured to utilize a regulated voltage; and   a voltage converter configured to receive a supply voltage and generate the regulated voltage for the load, the voltage converter including a voltage conversion circuit configured to receive the supply voltage as an input voltage and generate the regulated voltage as an output voltage, the voltage converter further including a control system configured to control the voltage conversion circuit, the control system including a driving unit configured to generate a driving signal that includes a plurality of pulses, each pulse having a width, the driving signal being provided to control the conversion of the input voltage into the output voltage, the control system further including a modulation unit configured to modulate the width of at least some of the pulses of the driving signal with a pulse width indication signal that is based on the output voltage to thereby allow adjustment of the output voltage, the control system further including a frequency control unit configured to generate a frequency control signal based on the pulse with indication signal, the frequency control signal configured to adjust a frequency of the driving signal.   
     
     
         16 . The electronic device of  claim 15  further comprising a power supply circuit configured to provide a battery voltage as the supply voltage. 
     
     
         17 . The electronic device of  claim 15  wherein the load includes a lighting device powered by the regulated voltage. 
     
     
         18 . The electronic device of  claim 17  wherein the lighting device includes a light emitting diode. 
     
     
         19 . The electronic device of  claim 15  wherein the load includes a radio-frequency component powered by the regulated voltage. 
     
     
         20 . The electronic device of  claim 19  wherein the radio-frequency component includes a radio-frequency amplifier.