Controller for DC to DC Converter

Abstract

A method includes starting a time count of a time interval at a start of a state change of a switch of a DC to DC converter; monitoring if the switch is in a skip mode; and disabling the skip mode in response to an expiration of the time interval so that the switch changes states at a frequency rate greater than an audible frequency for humans.

1 . A switching circuit comprising: 
 at least one switch; and    a controller configured to control a state of said at least one switch, said controller having a skip mode wherein said controller maintains said at least one switch in an OFF state, said controller responsive to a timer, said timer configured to count for a time interval, said controller responsive to expiration of said time interval to disable said skip mode so that said at least one switch changes states at a frequency rate based on said time interval.    
   
   
       2 . The switching circuit of  claim 1 , wherein said timer is coupled to an output terminal of said controller.  
   
   
       3 . The switching circuit of  claim 1 , wherein said at least one switch comprises a high side switch and a low side switch.  
   
   
       4 . The switching circuit of  claim 1 , wherein said controller is configured to control said state of said at least one switch with a periodic control signal, and wherein said timer is configured to count for said time interval upon a start of a period of said periodic control signal.  
   
   
       5 . The switching circuit of  claim 4 , wherein said periodic control signal comprises a pulse width modulated signal.  
   
   
       6 . The switching circuit of  claim 1 , wherein said frequency rate is between approximately 20 kHz and approximately 25 kHz.  
   
   
       7 . The switching circuit of  claim 1 , wherein time interval is between approximately 40 microseconds to approximately 50 microseconds.  
   
   
       8 . A method comprising: 
 starting a time count of a time interval at a start of a state change of a switch of a DC to DC converter;    monitoring if said switch is in a skip mode; and    disabling said skip mode in response to an expiration of said time interval so that said switch changes states at a frequency rate based on said time interval.    
   
   
       9 . The switching circuit of  claim 8 , wherein said frequency rate is between approximately 20 kHz and approximately 25 kHz.  
   
   
       10 . The switching circuit of  claim 8 , wherein time interval is between approximately 40 microseconds to approximately 50 microseconds.  
   
   
       11 . The method of  claim 8 , wherein said switch comprises a high side switch of a DC to DC converter, and said DC to DC converter also comprises a low side switch, said low and high side switch being open in said skip mode.  
   
   
       12 . The method of  claim 11 , wherein said disabling said skip mode in response to expiration of said time interval comprises closing said low side switch so that said high side switch changes states.  
   
   
       13 . The method of  claim 12 , further comprising controlling said high and low side switches with a periodic control signal, and wherein said closing of said low side switch causes discharging of an output capacitor of said DC to DC converter.  
   
   
       14 . The method of  claim 13 , wherein said periodic control signal comprises a pulse width modulated signal, and wherein a new pulse of said pulse width modulated signal is generated to turn on said high side switch when a voltage level of said output capacitor decreases to a set voltage level.  
   
   
       15 . A DC to DC converter comprising: 
 a high side and low side switch; and    a controller configured to control a state of said high side and low side switch, said controller having a skip mode wherein said low side and high side switch are open, said controller responsive to a timer, said timer configured to count for a time interval, said controller responsive to expiration of said time interval to disable said skip mode so that said high side switch changes states based on said time interval.    
   
   
       16 . The DC to DC converter of  claim 15 , wherein said controller disables said skip mode in response to expiration of said time interval by closing said low side switch.  
   
   
       17 . The DC to DC converter of  claim 16 , wherein said controller controls said state of said high and low side switches with a periodic control signal, and wherein said closing of said low side switch causes discharging of an output capacitor of said DC to DC converter.  
   
   
       18 . The DC to DC converter of  claim 17 , wherein said periodic control signal comprises a pulse width modulated signal, and wherein a new pulse of said pulse width modulated signal is generated to turn on said high side switch when a voltage level of said output capacitor decreases to a set voltage level.  
   
   
       19 . The DC to DC converter of  claim 15 , wherein said frequency rate is between approximately 20 kHz and approximately 25 kHz  
   
   
       20 . The DC to DC converter of  claim 15 , wherein time interval is between approximately 40 microseconds to approximately 50 microseconds.