Method and System for Voltage Tracking and Sequencing in a Power Supply

Abstract

A method for controlling multiple voltages in a power supply includes providing a plurality of DC to DC power converters. Each power converter includes a pulse width modulator controller having a control pin. The method also includes when a voltage supply to the power controllers reads a particular level. After the particular level is met, the method includes providing a respective rising ramp control signal to each respective control pin of the pulse width modulator controller such that each respective power converter generates desired voltage level over time characteristics.

1 . A method for controlling multiple voltages in a power supply comprising: 
 providing a plurality of DC to DC power converters each having a pulse width modulator controller having a control pin;    detecting when a voltage supply to the power converters reaches a particular level; and    after the particular level is met, initiating turning on or turning off of the respective power converter by providing a respective rising ramp control signal to each respective control pin of the pulse width modulator controller such that each respective power converter generates desired voltage level over time characteristics according to a desired voltage differential with respect to the other power converters.    
   
   
       2 . The method of  claim 1 , wherein the control pin is a soft start pin.  
   
   
       3 . The method of  claim 1 , wherein the control pin is a pin operable to receive a set point for the pulse width modulator controller.  
   
   
       4 . The method of  claim 1 , wherein the ramp control signals are generated by respective circuits having desired time constants.  
   
   
       5 . The method of  claim 1 , and further comprising, for at least one pair of the plurality of power converters, monitoring a voltage differential between the voltages generated by each power converter in the pair and, upon detection of a particular differential voltage level providing a falling ramp control signal to the soft start input of each of the power converters that initiates a soft stop such that each respective power converter generates desired voltage level over time characteristics.  
   
   
       6 . The method of  claim 5 , wherein the falling ramp control signal is provided to the soft start input of each of the power converters by respective ramp circuits having desired time constants.  
   
   
       7 . The method of  claim 2 , and further comprising, for at least one pair of the plurality of power converters, monitoring a voltage differential between the voltages generated by each power converter in the pair and, upon detection of a particular differential voltage level, providing a falling ramp control signal to the soft start input of each of the power converters that initiates a soft stop such that each respective power converter generates desired voltage level over time characteristics.  
   
   
       8 . The method of  claim 7 , wherein the falling ramp control signal is provided to the soft start input of each of the power converters by the respective ramp circuits having desired time constants.  
   
   
       9 . The method of  claim 2 , and further comprising: 
 monitoring the voltage supply to the pulse width modulator controller;    detecting when the voltage supply falls below a specific level; and    in response to detecting when the voltage supply falls below a specified level, providing a falling ramp control signal to each respective soft start input such that each respective power converter generates desired voltage level over time characteristics.    
   
   
       10 . The method of  claim 7 , wherein the falling ramp control signals are provided to the soft start input of each of the power converters through respective ramp circuits having desired time constraints.  
   
   
       11 . An apparatus for controlling multiple voltages in a power supply comprising: 
 a plurality of DC to DC power converters each having a pulse-width-modulator controller having a control pin;    a detection means for detecting when an input voltage supply to the power controller reaches a particular level; and    a ramping means for initiating turning on or turning off of the respective power converter by providing a rising ramp control signal to each control pin such that each respective power converter generates desired voltage over time characteristics according to a desired voltage differential with respect to the other power converters.    
   
   
       12 . The apparatus of  claim 11 , wherein the control pin is a soft start pin.  
   
   
       13 . The apparatus of  claim 11 , wherein the control pin is pin operable to receive a set point for the controller.  
   
   
       14 . The apparatus of  claim 9 , and further comprising, for at least one pair of the plurality of power converters, a voltage differential means for monitoring the voltages generated by each power converter in the pair, and, upon detection of a particular voltage differential, providing a falling ramp control signal to the control pin of each of the power converters to initiate a soft stop.  
   
   
       15 . The apparatus of  claim 11 , further comprising a voltage ramping means for controlling tracking of the termination of the voltage supplied to the control pin of each of the power converters.  
   
   
       16 . The apparatus of  claim 15 , wherein the ramping means and the voltage differential ramping means are different means.  
   
   
       17 . A power supply comprising: 
 a plurality of DC to DC power converters, each having a pulse width modulation controller having a soft start switch;    a voltage tracking and under voltage lockout circuit operable to determine when a voltage level supplied to the power controller reaches predetermined levels and in response provide first control signals to each respective soft start input of the power converter;    at least one voltage differential protection circuit operable to detect a voltage differential between voltages generated by a respective pair of the power converters, determine whether the detected voltage level meets specific criteria, and in response provide an appropriate control signal to the soft start switch of each power converter;    a plurality of respective ramp circuits associated with respective ones of the power converters, each ramp circuit operable to: 
 receive respective control signals from the voltage tracking and under voltage lockout circuit and initiate turning on or turning off of the respective power converter by providing a rising ramp control signal to each respective soft start input of the power converters according to a time constant of the ramp circuit; and  
 receive respective voltage levels from the at least one voltage differential protection circuit and delay providing the second control signals to the soft start switch of the respective power converter according to a time constant of the ramp circuit to achieve a desired voltage differential with respect to the other power converters.  
   
   
   
       18 . The power supply of  claim 17 , wherein the plurality of respective ramp circuits each comprise an RC circuit.  
   
   
       19 . The power supply of  claim 18 , wherein each of the plurality of respective ramp circuits have a different ramp rate than any of the other ramp circuits such that either of the first or second control signals are provided to each of the power converters at a different rate.  
   
   
       20 . The power supply of  claim 17 , wherein the plurality of DC power converters comprises five power converters.  
   
   
       21 . The power supply of  claim 20 , wherein the five power converters comprise a  12  volt to 1.8 volt power converter, a 12 volt to 2.5 volt power converter, a  12  volt to 3.3 volt power converter, a 12 volt to 1.35 volt power converter, and a 12 volt to 1.5 volt power converter.  
   
   
       22 . The power supply of  claim 17 , wherein the at least one voltage differential protection circuit comprises three voltage differential protection circuits, one of the three voltage differential protection circuits monitoring a voltage differential between the 12 volt to 3.3 volt power converter and the 1.35 volt power converter, a second voltage protection circuit monitoring the voltage differential between the 12 volt to 3.3 volt power converter and the 12 volt to 2.5 volt power converter, and a third voltage differential protection circuit monitoring the voltage differential between the 12 volt to 2.5 volt power converter and the 12 volt to 1.8 volt power converter.  
   
   
       23 . The power supply of  claim 17 , wherein the voltage tracking circuit comprises a plurality of field effect transistors for selectively providing the first control signals to the respective power converters.  
   
   
       24 . The power supply of  claim 17 , wherein the plurality of respective voltage differential detection circuits and a plurality of transistors each operable to selectively transmit control signals to the soft start input of each power converter.  
   
   
       25 . A power supply regulator comprising: 
 a plurality of DC to DC power converters, each having a pulse width modulation controller having a soft start pin;    a voltage tracking and under voltage lockout circuit operable to determine when a voltage level supplied to the power controller reaches a predetermined threshold and in response provide control signals to each respective soft start input of the power converter;    a plurality of respective ramp circuits associated with respective ones of the power converters, each ramp circuit operable to receive respective control signals from the voltage tracking and voltage lockout circuit and initiate turning on or turning off of the respective power converter by providing a respective rising ramp control signal to each respective soft start input of the power converter according to a time constant of the ramp circuit according to a desired voltage differential with respect to the other power converters.    
   
   
       26 . The power supply of  claim 25 , wherein the plurality of respective ramp circuits each comprise an RC circuit.  
   
   
       27 . The power supply of  claim 26 , wherein the plurality of respective ramp circuits each have a different ramp time constant such that the control signal is provided to each of the power converters at a different rate operable to produce a minimal voltage delta during power supply turn on or power supply turn off.  
   
   
       28 . The power supply of  claim 21 , wherein the plurality of DC power converters comprises five power converters.  
   
   
       29 . The power supply of  claim 28 , wherein the five power converters comprise a 12 volt to 1.8 volt power converter, a 12 volt to 2.5 volt power converter, a 12 volt to 3.3 volt power converter, a 12 volt to 1.35 volt power converter, and a 12 volt to 1.5 volt power converter.  
   
   
       30 . The power supply of  claim 25 , wherein the ramp circuit is coupled to an under voltage lockout circuit.