Control circuits and methods for voltage converters

Abstract

Control circuits and methods for voltage converters. In some embodiments, a voltage converter can include a voltage conversion circuit configured to convert a first voltage to a second voltage, and capable of operating in a continuous mode or a discontinuous mode. The voltage converter can further include a mode controller configured to control transition from the continuous mode to the discontinuous mode based on a first threshold level associated with an inductance current of the voltage conversion circuit, and to control transition from the discontinuous mode to the continuous mode based on a second threshold level associated with the inductance current of the voltage conversion circuit.

What is claimed is: 
     
         1 . A voltage converter comprising:
 a voltage conversion circuit configured to convert a first voltage to a second voltage, and capable of operating in a continuous mode or a discontinuous mode; and   a mode controller configured to control transition from the continuous mode to the discontinuous mode based on a first threshold level associated with an inductance current of the voltage conversion circuit, and to control transition from the discontinuous mode to the continuous mode based on a second threshold level associated with the inductance current of the voltage conversion circuit.   
     
     
         2 . The voltage conversion circuit of  claim 1  wherein the voltage conversion circuit includes an inductor configured to be charged and discharged to facilitate the conversion of the first voltage to the second voltage. 
     
     
         3 . The voltage conversion circuit of  claim 2  wherein the inductance current includes a current associated with the inductor. 
     
     
         4 . The voltage converter of  claim 2  further comprising a drive circuit configured to provide a drive signal to the voltage conversion circuit to control the charging and discharging of the inductor. 
     
     
         5 . The voltage converter of  claim 4  wherein the mode controller is configured to provide a mode-switching signal to the drive circuit to control the transition between the continuous mode and the discontinuous mode. 
     
     
         6 . The voltage converter of  claim 1  wherein the continuous mode includes a pulse width modulation (PWM) mode, and the discontinuous mode includes a pulse frequency modulation (PFM) mode. 
     
     
         7 . The voltage converter of  claim 1  wherein the mode controller includes an inductance signal detection unit configured to detect the inductance current and output at least one of a peak value IL_peak and a valley value IL_valley of the detected inductance current. 
     
     
         8 . The voltage converter of  claim 7  wherein the mode controller further includes a switching determination circuit configured to determine whether to transition between the continuous mode and the discontinuous mode based on one or more of the peak value IL_peak, the valley value IL_valley, and a peak-to-peak value ΔIL, of the inductance current. 
     
     
         9 . The voltage converter of  claim 8  wherein the first threshold level has a value of (ΔIL/2)−|IL_valley|, such that the switching determination circuit determines whether to transition from the continuous mode to the discontinuous mode when a load current ILoad on a load powered by the voltage converter is less than or equal to the first threshold level. 
     
     
         10 . The voltage converter of  claim 8  wherein the first threshold level has a selected value of the valley value IL_valley of the inductance current. 
     
     
         11 . The voltage converter of  claim 8  wherein the second threshold level has a value of a times IL_peak, such that the switching determination circuit determines whether to transition from the discontinuous mode to the continuous mode when a load current ILoad on a load powered by the voltage converter is greater than the second threshold level, the quantity a being greater than or equal to ½ and less than 1. 
     
     
         12 . The voltage converter of  claim 8  wherein the switching determination circuit is configured to determine whether to transition from the discontinuous mode to the continuous mode based on the peak value IL_peak or the valley value IL_valley of the detected inductance current. 
     
     
         13 . A method for operating a voltage converter, the method comprising:
 providing a voltage conversion circuit for converting a first voltage to a second voltage in a continuous mode or a discontinuous mode; and   controlling a transition from the continuous mode to the discontinuous mode based on a first threshold level associated with an inductance current of the voltage conversion circuit, and a transition from the discontinuous mode to the continuous mode based on a second threshold level associated with the inductance current of the voltage conversion circuit.   
     
     
         14 . The method of  claim 13  wherein the converting of the first voltage to the second voltage includes charging and discharging of an inductor of the voltage conversion circuit. 
     
     
         15 . The method of  claim 14  further comprising generating a drive signal for the voltage conversion circuit to control the charging and discharging of the inductor. 
     
     
         16 . The method of  claim 14  wherein the controlling of the transition includes detecting the inductance current and providing at least one of a peak value IL_peak and a valley value IL_valley of the detected inductance current. 
     
     
         17 . The method of  claim 16  wherein the controlling of the transition further includes determining whether to transition between the continuous mode and the discontinuous mode based on one or more of the peak value IL_peak, the valley value IL_valley, and a peak-to-peak value ΔIL, of the inductance current. 
     
     
         18 . An electronic apparatus comprising:
 a power management system configured to provide a supply voltage;   a module configured to provide a functionality for the electronic apparatus, and to utilize a regulated voltage; and   a voltage converter including a voltage conversion circuit configured to convert the supply voltage to the regulated voltage, and capable of operating in a continuous mode or a discontinuous mode, the voltage converter further including a mode controller configured to control transition from the continuous mode to the discontinuous mode based on a first threshold level associated with an inductance current of the voltage conversion circuit, and to control transition from the discontinuous mode to the continuous mode based on a second threshold level associated with the inductance current of the voltage conversion circuit.   
     
     
         19 . The electronic apparatus of  claim 18  wherein the electronic apparatus is a portable device capable of being powered by a battery. 
     
     
         20 . The electronic apparatus of  claim 19  wherein the portable device includes a mobile phone, a tablet computer, a display, an eBook reader, or a portable digital media display.