Power management system

Abstract

The disclosed technology can be used to convert direct-current voltage and current from an input to a different or the same voltage and current at an output. One example direct-current to direct-current (DC-DC) power converter includes a first switch connected between a source voltage and a first side of an inductor, a second switch connected between the first side of the inductor and a ground, a third switch connected between a second side of the inductor and the ground, and a fourth switch connected between the second side of the inductor and a capacitor. The power converter may further include a comparator configured to compare an output voltage at the capacitor to a threshold voltage and based on the result of the comparison selectively activate or deactivate the first, second, third, and fourth switches in a power cycle.

What is claimed is: 
     
         1 . A direct-current to direct-current (DC-DC) power converter circuit, comprising:
 a first switch connected between an input configured to receive a source voltage and a first side of an inductor;   a second switch connected between the first side of the inductor and another input configured for connection to a ground;   a third switch connected between a second side of the inductor and the first side of the inductor; and   a comparator configured to compare an output voltage of a capacitor coupled to the third switch to a threshold voltage, and to activate or deactivate the first, the second and the third switches in a power cycle sequence when the output voltage goes below the threshold voltage.   
     
     
         2 . The DC-DC power converter of  claim 1 , wherein the power cycle sequence includes:
 a first switching time at which the first switch to turn on and the second switch and the third switch to turn off;   a second switching time at which the second switch to turn on and the first switch and the third switch to turn off; and   a third switching time at which the third switch to turn on and the first switch and the second switch to turn off.   
     
     
         3 . The DC-DC converter of  claim 1 , wherein the third switch is configured to conduct a leakage current associated with a path of the first switch to charge the capacitor. 
     
     
         4 . The DC-DC converter of  claim 3 , wherein an efficiency of the DC-DC converter is improved at light load conditions due to charging of the capacitor by the leakage current. 
     
     
         5 . The DC-DC converter of  claim 1 , wherein closure of the third switch is operable to reduce or suppress ringing associated with the inductor. 
     
     
         6 . The DC-DC converter of  claim 1 , wherein each of the first switch, the second switch and the third switch is implemented as one of a bipolar switch, a CMOS, a NMOS, or a PMOS switch with or without a gate drive boost. 
     
     
         7 . The DC-DC converter of  claim 1 , further including a resistor positioned in a loop formed by the third switch and the inductor 
     
     
         8 . The DC-DC converter of  claim 1 , wherein closure of the third switch causes a current in the inductor to be reduced to zero or near zero. 
     
     
         9 . The DC-DC converter of  claim 2 , wherein the converter is configured to control the first, second and third switching times of the power cycle sequence to control a peak current of the inductor. 
     
     
         10 . The DC-DC converter of  claim 2 , wherein the converter is configured to control the first, second and third switching times of the power cycle sequence to limit a ripple of an output voltage of the DC-DC convertor to a predetermined level. 
     
     
         11 . The DC-DC converter of  claim 1 , wherein the capacitor is a first capacitor, and the DC-DC converter further comprises a fourth switch configured to charge a second capacitor to a second output voltage during a time period different from a time period when the first capacitor is being charged. 
     
     
         12 . The DC-DC power converter of  claim 11 , further comprising:
 a fifth switch connected between the second side of the inductor and the first capacitor, configured to connect the first capacitor to the second side of the inductor during the time period when the first capacitor is being charged, and   a sixth switch connected between the first side of the inductor and the second capacitor, configured to conduct a leakage current from the first switch to the second capacitor.   
     
     
         13 . The DC-DC converter of  claim 12 , wherein the power cycle sequence includes:
 a first time instance at which the first switch and the fifth switch to turn on, and the second switch, the third switch, the fourth switch and the sixth switch to turn off;   a second time instance at which the second switch and the fifth switch to turn on, and the first switch, the third switch, the fourth switch and the sixth switch to turn off;   a third time instance at which the third switch is on and the first switch and second switch and the fourth switch and the fifth switch and the sixth switch to turn off;   a fourth time instance at which the first switch and the fourth switch are on, and the second switch, the third switch the fifth switch and the sixth switch are off;   a fifth time instance at which the second switch and the fourth switch to turn on, and the first switch, the third switch, the fifth switch and the sixth switch to turn off; and   a sixth time instance at which the sixth switch is on, and the first switch, second switch, the third switch, the fourth switch and the fifth switch to turn off.   
     
     
         14 . The DC-DC converter of  claim 12 , wherein the first and the second capacitors are served on a round robin basis or on a priority basis. 
     
     
         15 . The DC-DC converter of  claim 12 , configured to allow a leakage current from the first switch to flow into the third and sixth switches to improve efficiency and reduce power waste. 
     
     
         16 . The DC-DC power converter of  claim 1 , further including a controller configured to control a timing and a repetition of the power cycle sequence. 
     
     
         17 . The DC-DC power converter of  claim 16 , wherein the controller is configured to maintain the peak-to-peak size of a voltage ripple to within a predetermined range of voltage values. 
     
     
         18 . The DC-DC power converter of  claim 16 , wherein the controller is configured to enable user programmable control of the power cycle sequence.