Method and apparatus to select a parameter/mode based on a measurement during an initialization period

Abstract

A power supply control circuit includes a threshold detection circuit coupled to a first terminal to measure a signal at the first terminal during a duration of an initialization period after a fourth terminal has been charged to a supply threshold value. A regulator circuit is coupled between a second terminal and the fourth terminal to charge the fourth terminal to the supply threshold value during the initialization period of the power supply control circuit. A selection circuit is coupled to the threshold detection circuit to select a parameter/mode in response to the signal measured at the first terminal. The first terminal is further coupled to receive one or more additional signals during normal operation at times other than the initialization period to provide at least one additional function for the power supply control circuit after the initialization period is complete.

What is claimed is: 
     
         1 . A power supply control circuit, comprising:
 a threshold detection circuit coupled to a first terminal of the power supply control circuit to measure a signal at the first terminal of the power supply control circuit during a duration of an initialization period after a fourth terminal of the power supply control circuit has been charged to a supply threshold value;   a regulator circuit coupled to the fourth terminal of the power supply control circuit to charge the fourth terminal of the power supply control circuit to the supply threshold value during the initialization period of the power supply control circuit; and   a selection circuit coupled to the threshold detection circuit to select a parameter/mode of the power supply control circuit in response to the signal measured at the first terminal of the power supply control circuit, wherein the first terminal of the power supply control circuit is further coupled to receive one or more additional signals during normal operation at times other than the initialization period to provide at least one additional function for the power supply control circuit after the initialization period is complete.   
     
     
         2 . The power supply control circuit of  claim 1  wherein the at least one additional function comprises a feedback terminal function for the power supply control circuit. 
     
     
         3 . The power supply control circuit of  claim 1  coupled to a switch, wherein the switch is coupled to be driven by the power supply control circuit. 
     
     
         4 . The power supply control circuit of  claim 3 , wherein the parameter/mode comprises a peak current threshold level of a current flowing in the switch. 
     
     
         5 . The power supply control circuit of  claim 3  comprised in a power supply circuit and coupled to receive a signal representative of an input voltage to the power supply circuit, wherein the parameter/mode comprises a parameter that sets an adjustment of a peak current threshold level of a current flowing in the switch in response to the input voltage. 
     
     
         6 . The power supply control circuit of  claim 5 , wherein the parameter/mode further comprises a peak current threshold level in the switch at a certain value of the input voltage. 
     
     
         7 . The power supply control circuit of  claim 6 , wherein the switch and the power supply control circuit are comprised in an integrated circuit. 
     
     
         8 . The power supply control circuit of  claim 1  wherein the signal measured at the first terminal of the power supply control circuit flows through a resistive circuit coupled between the fourth terminal of the power supply control circuit and the first terminal of the power supply control circuit. 
     
     
         9 . The power supply control circuit of  claim 1  wherein the parameter/mode that is set during the initialization period comprises an operating frequency of the power supply control circuit. 
     
     
         10 . The power supply control circuit of  claim 9  wherein the operating frequency is a maximum operating frequency of the power supply control circuit. 
     
     
         11 . The power supply control circuit of  claim 1  wherein the signal measured at the first terminal of the power supply control circuit is a current. 
     
     
         12 . The power supply control circuit of  claim 1  wherein the regulator circuit is coupled between a second terminal of the power supply control circuit and the fourth terminal of the power supply control circuit.