Circuit for multiplexing digital and analog information via single pin of driver for switched mosfets of dc-dc converter

Abstract

Multiple characteristics of a DC-DC converter, such as its mode of operation (e.g., either forced continuous conduction mode, or discontinuous conduction mode), and an operational parameter (such as the dead-time between switching times of the output switching devices (upper and lower MOSFETs) of the converter, whose associated driver integrated circuit has a pin usage that leaves only a single pin available for auxiliary purposes, are programmed by a single pin-based digital and analog information extracting circuit that couples both digital information and analog information within the same control signal to the driver IC by way of only the one available pin.

1 . A driver circuit for a DC-DC converter, comprising:
 an input pin;   a sign detect circuit coupled to the input pin, to detect at least one of a positive polarity and a negative polarity of an analog current flowing through the pin; and   an absolute value circuit coupled to the input pin, to sense an absolute value of a steady state analog current flowing through the pin.   
     
     
         2 . The driver circuit of  claim 1 , wherein the absolute value circuit further comprises a circuit to sense a magnitude of the absolute value of the steady state analog current flowing through the pin. 
     
     
         3 . The driver circuit of  claim 1 , further comprising:
 a mode select circuit coupled to an output of the sign detect circuit, to select at least one of a forced continuous conduction mode and a discontinuous conduction mode of operation of the DC-DC converter; and   a delay circuit coupled to an output of the absolute value circuit, to select a dead-time between switching times of a plurality of switching transistors of the DC-DC converter.   
     
     
         4 . The driver circuit of  claim 1 , wherein the analog current flowing through the pin comprises a control signal including digital information to select a mode of operation of the DC-DC converter, and analog information to program an operational parameter of the DC-DC converter. 
     
     
         5 . A method of operation of a driver circuit for a DC-DC converter, comprising:
 flowing an analog current through an input pin of the driver circuit;   detecting at least one of a positive polarity and a negative polarity of the analog current flowing through the pin; and   sensing an absolute value of a steady state analog current flowing through the pin.   
     
     
         6 . The method of  claim 5 , wherein the sensing further comprises sensing a magnitude of the absolute value of the steady state analog current flowing through the pin. 
     
     
         7 . The method of  claim 5 , further comprising:
 selecting at least one of a forced continuous conduction mode and a discontinuous conduction mode of operation of the DC-DC converter; and   selecting a dead-time between switching times of a plurality of switching transistors of the DC-DC converter.   
     
     
         8 . A digital information extraction circuit, comprising:
 an input pin adapted to receive an input signal including digital information and analog information; and   a circuit coupled to the input pin, wherein the circuit is adapted to extract the digital information from the input signal based upon a direction of flow of a steady state analog current through the input pin.   
     
     
         9 . The digital information extraction circuit of  claim 8 , wherein the flow of the steady state analog current through the input pin is responsive to an application of the input signal to an input of the circuit. 
     
     
         10 . The digital information extraction circuit of  claim 8 , wherein the input signal is a control signal for a DC-DC converter and utilized to select one mode of a plurality of modes of operation of the DC-DC converter, and an output of the digital information extraction circuit is coupled to an input of a driver circuit for the DC-DC converter. 
     
     
         11 . The digital information extraction circuit of  claim 8 , wherein the digital information extraction circuit is adapted to extract the digital information from the input signal based upon a polarity of an electrical condition produced at the input pin in response to an application of the input signal to an input of the circuit. 
     
     
         12 . The digital information extraction circuit of  claim 8 , wherein the digital information is associated with a plurality of logic voltage levels of the input signal. 
     
     
         13 . The digital information extraction circuit of  claim 8 , further comprising:
 a programming resistor coupled to the input pin, wherein the programming resistor is adapted to couple the input signal to the input pin.   
     
     
         14 . The digital information extraction circuit of  claim 8 , wherein the digital information is associated with transitions between logic voltage levels of the input signal. 
     
     
         15 . The digital information extraction circuit of  claim 8 , wherein the circuit is adapted to extract the digital information from the input signal based upon a polarity of a voltage pulse produced at the input pin in response to an application of the input signal to an input of the circuit. 
     
     
         16 . The digital information extraction circuit of  claim 8 , further comprising a high-pass filter coupled to the input pin. 
     
     
         17 . An analog information extraction circuit, comprising:
 an input pin adapted to receive an input signal including digital information and analog information; and   a circuit coupled to the input pin, wherein the circuit is adapted to extract the analog information from the input signal based upon a magnitude of a steady state analog current flowing through the input pin.   
     
     
         18 . The analog information extraction circuit of  claim 17 , wherein the analog information is associated with an absolute value of the steady state analog current flowing through the input pin in response to an application of the input signal to an input of the circuit. 
     
     
         19 . The analog information extraction circuit of  claim 17 , further comprising:
 a programming resistor coupled to the input pin, wherein the programming resistor is adapted to couple the input signal to the input pin.   
     
     
         20 . The analog information extraction circuit of  claim 17 , wherein the input signal is a control signal for a DC-DC converter and utilized to select one mode of a plurality of modes of operation of the DC-DC converter, and an output of the analog information extraction circuit is coupled to an input of a driver circuit for the DC-DC converter. 
     
     
         21 . A method of operation of a digital information extraction circuit, comprising:
 receiving at an input pin of the digital information extraction circuit, an input signal including digital information and analog information;   detecting a direction of flow of a steady state analog current through the input pin; and   extracting the digital information from the input signal based upon the direction of flow.   
     
     
         22 . The method of  claim 21 , wherein the detecting further comprises sensing a polarity of an electrical condition produced at the input pin in response to the receiving; and
 the extracting further comprises extracting the digital information based upon the polarity of the electrical condition.   
     
     
         23 . The method of  claim 21 , wherein the detecting further comprises sensing a plurality of logic voltage levels of the input signal; and
 the extracting further comprises extracting the digital information based upon the plurality of logic voltage levels.   
     
     
         24 . The method of  claim 21 , wherein the detecting further comprises sensing transitions between logic voltage levels of the input signal; and
 the extracting further comprises extracting the digital information based upon the transitions between logic voltage levels.   
     
     
         25 . The method of  claim 21 , wherein the detecting further comprises sensing a polarity of a voltage pulse produced at the input pin in response to the receiving; and
 the extracting further comprises extracting the digital information based upon the polarity of the voltage pulse.   
     
     
         26 . A method of operation of an analog information extraction circuit, comprising:
 receiving at an input pin of the analog information extraction circuit, an input signal including digital information and analog information;   detecting a magnitude of a steady state analog current flowing though the input pin; and   extracting the analog information from the input signal based upon the magnitude of the steady state analog current.   
     
     
         27 . The method of  claim 26 , wherein the detecting further comprises sensing an absolute value of the steady state analog current; and
 the extracting further comprises extracting the analog information based upon the absolute value of the steady state analog current.   
     
     
         28 . The method of  claim 26 , further comprising:
 coupling the extracted analog information to an input of a driver circuit for a DC-DC converter.   
     
     
         29 . A circuit for multiplexing digital information and analog information contained in a control signal, by way of a single pin of a driver circuit for a DC-DC converter, wherein said digital information may be used to select one of plural modes mode of operation of said converter, and wherein said analog information may be used to program an operational parameter of said converter, said circuit comprising:
 an input circuit through which said control signal is applied to said single pin of said driver circuit;   a digital information extraction circuit coupled between said single pin and said driver circuit, and being operative to extract said digital information from said control signal and to supply said digital information to said driver circuit; and   an analog information extraction circuit coupled between said single pin and said driver circuit, and being operative to extract said analog information from said control signal and to supply said analog information to said driver circuit.   
     
     
         30 . A method of multiplexing digital information and analog information contained in a control signal, by way of a single pin of a driver circuit for a DC-DC converter, wherein said digital information is used to select one of plural modes mode of operation of said converter, and wherein said analog information is used to program an operational parameter of said converter for each of said plural modes of operation of said converter, said method comprising:
 (a) coupling said control signal through an input circuit through to said single pin of said driver circuit to produce a signal at said single pin of said driver circuit;   (b) processing said signal produced in (a) at said single pin of said driver circuit so as to extract therefrom said digital information, and supplying said digital information to said driver circuit; and   (c) processing said signal produced in (a) at said single pin of said driver circuit so as to extract therefrom said analog information, and supplying said analog information to said driver circuit.   
     
     
         31 . In a driver circuit for a DC-DC converter, the improvement comprising a multiplexing circuit for multiplexing digital information and analog information contained in a control signal by way of a single pin of said driver circuit, said digital information being representative of a selected on one of plural modes mode of operation of said converter, and said analog information being representative of an operational parameter of said converter, said multiplexing circuit including an input circuit through which said control signal is applied to said single pin of said driver circuit, a digital information extraction circuit coupled between said single pin and said driver circuit, and being operative to extract said digital information from said control signal and to supply said digital information to said driver circuit, and an analog information extraction circuit coupled between said single pin and said driver circuit, and being operative to extract said analog information from said control signal and to supply said analog information to said driver circuit.