Pre-charging a voltage converter

Abstract

A system may include a pre-charge stage and a voltage converter. The pre-charge stage may include a controller circuit configured to generate a control voltage and a current regulator electrically coupled to the controller circuit and configured to generate a first voltage, a second voltage, and a third voltage. The voltage converter may include a capacitor, a hold capacitor, and switches. The capacitor may include a first plate and a voltage on the first plate may be equal to the first voltage. The capacitor may include a second plate and a voltage on the second plate may be equal to the second voltage. The hold capacitor may include a plate and a voltage on the plate may be equal to the third voltage. The current regulator may be configured to regulate a current on the switches during accumulation of an initial charge on the capacitor and the hold capacitor.

1 . A pre-charge stage configured to:
 generate a first voltage based on an input voltage, a scaled feedback voltage, and a gain voltage;   pre-charge a voltage on a first plate of a capacitor to be equal to the first voltage;   regulate a current on a switch during accumulation of an initial charge on the capacitor;   generate a feedback voltage based on the first voltage; and   scale the feedback voltage to the scaled feedback voltage.   
     
     
         2 . The pre-charge stage of  claim 1 , wherein the pre-charge stage limits the current on the switch during accumulation of the initial charge on the capacitor to regulate the current on the switch. 
     
     
         3 . The pre-charge stage of  claim 1 , wherein:
 the feedback voltage comprises a first feedback voltage and a second feedback voltage;   the scaled feedback voltage comprises a first scaled feedback voltage and a second scaled feedback voltage; and   the pre-charge stage is configured to:
 scale the input voltage to a scaled input voltage; 
 compare the scaled input voltage to the first scaled feedback voltage; 
 generate a first comparison voltage based on the comparison; 
 compare the scaled input voltage to the second scaled feedback voltage; 
 generate a second comparison voltage based on the comparison; 
 generate the first scaled feedback voltage based on the first feedback voltage; 
 generate the second scaled feedback voltage based on the second feedback voltage; and 
 generate a control voltage based on the first comparison voltage and the second comparison voltage. 
   
     
     
         4 . The pre-charge stage of  claim 3 , wherein:
 the first comparison voltage comprises a digital voltage; and   a high voltage indicates the scaled input voltage is greater than the first scaled feedback voltage and a low voltage indicates the first scaled feedback voltage is greater than the scaled input voltage.   
     
     
         5 . The pre-charge stage of  claim 3 , wherein the scaled input voltage is a divided version of the input voltage. 
     
     
         6 . The pre-charge stage of  claim 3 , wherein the pre-charge stage comprises a first switch configured to transition between an open position and a closed position based on the control voltage, in the closed position the first switch propagates the input voltage such that the first voltage is equal to the input voltage. 
     
     
         7 . The pre-charge stage of  claim 6  configured to:
 generate an inverted gain voltage based on the gain voltage; and 
 generate a first OR voltage based on the first comparison voltage and the inverted gain voltage, wherein the pre-charge stage is configured to generate the control voltage based on the first OR voltage. 
 
     
     
         8 . The pre-charge stage of  claim 7  configured to:
 generate a first AND voltage based on the first OR voltage and an enable voltage; and 
 generate the control voltage based on the first AND voltage. 
 
     
     
         9 . The pre-charge stage of  claim 8  configured to generate the control voltage based on the input voltage and the first AND voltage. 
     
     
         10 . The pre-charge stage of  claim 1 , wherein:
 the pre-charge stage is configured to:
 generate a second voltage and a third voltage based on the input voltage, the scaled feedback voltage, and the gain voltage; and 
 generate the feedback voltage further based on the third voltage; and 
   the pre-charge stage is electrically coupled to a corresponding voltage converter comprising:
 the capacitor comprising:
 the first plate; and 
 a second plate, wherein the pre-charge stage is configured to pre-charge a voltage on the second plate to be equal to the second voltage; and 
 
 a hold capacitor comprising a plate, wherein the pre-charge stage is configured to pre-charge a voltage on the plate to be equal to the third voltage. 
   
     
     
         11 . The pre-charge stage of  claim 10  configured to:
 compare the input voltage to the scaled feedback voltage; and 
 generate the first voltage based on the comparison and the gain voltage, the gain voltage comprising a digital voltage, wherein a low voltage indicates a first gain setting is to be used in the corresponding voltage converter and a high voltage indicates a second gain setting is to be used in the corresponding voltage converter. 
 
     
     
         12 . The pre-charge stage of  claim 1 , configured to:
 pre-charge the voltage on the first plate during a pre-charge phase; and   regulate the current on the switch during accumulation of the initial charge on the capacitor during an operation phase.   
     
     
         13 . The pre-charge stage of  claim 12 , wherein:
 the pre-charge phase ends and the operation phase starts after a programmable time period; and   the current on the switch at initiation of the operation phase is reduced due to the first plate being pre-charged by the pre-charge stage.   
     
     
         14 . The pre-charge stage of  claim 12  configured to generate the first voltage further based on an enable voltage comprising a digital voltage, wherein a high voltage indicates the pre-charge phase is occurring and a low voltage indicates the operation phase is occurring.