Low noise external enable switcher control signal using on-chip switcher

Abstract

A method and system is disclosed for powering device sub-circuitry of an electronic device. The sub-circuitry may be used to provide control signals to a direct current switcher on a main system board, thus eliminating passive circuitry typically associated with the sub-circuitry. Furthermore, by actively generating the control signals for the direct current switcher, explicit timing control circuitry is not required to synchronize the transmitted power to the sub-circuitry.

1 . An electronic device, comprising:
 a first circuit board comprising a power management unit, the power management unit comprising a dc/dc converter, wherein the dc/dc converter comprises a slave power controller coupled to passive circuit components configured to convert a first dc voltage to a second dc voltage; and   a second circuit board comprising a sub-circuit and a master power controller, the sub-circuit being configured to receive the second dc voltage, the master power controller being operably coupled to the slave power controller to cause the slave power controller to switch the first dc voltage relative to the passive circuit components to generate the second dc voltage.   
   
   
       2 . The electronic device of  claim 1 , wherein the slave power controller comprises a slave switcher coupled to a slave switch, and wherein the master power controller comprises a master switcher coupled to a master switch, the master switch being operably coupled to the slave switcher; and
 wherein the master switcher is operable to switch the master switch on and off to alternatively enable and disable the slave switcher to cause the slave switcher to switch the slave switch on and off to cause the first dc voltage to be switched relative to the passive circuit components to generate the second dc voltage.   
   
   
       3 . The electronic device of  claim 1 , wherein the first circuit board is separate from the second circuit board. 
   
   
       4 . The electronic device of  claim 1 , wherein the slave power controller is arranged relative to the passive components and an input for the first dc voltage to form one of a buck dc/dc voltage converter, a boost dc/dc voltage converter, or a flyback dc/dc voltage converter. 
   
   
       5 . The electronic device of  claim 1 , wherein the sub-circuit comprises display logic. 
   
   
       6 . The electronic device of  claim 1 , wherein the master power controller circuit controls the slave power controller based at least in part on the power requirements of the sub-circuit. 
   
   
       7 . The electronic device of  claim 6 , wherein the master power controller receives from the sub-circuit a signal indicative of the power requirement of the sub-circuit and receives the second dc voltage as a feedback signal, and wherein the master power controller controls the slave power controller based at least in part on a comparison of the power requirement signal and the feedback signal. 
   
   
       8 . The electronic device of  claim 1 , wherein the power management unit comprises filtering circuitry coupled between the master power controller and the slave power controller. 
   
   
       9 . A handheld electronic device comprising:
 a power management unit comprising a dc/dc converter, wherein the dc/dc converter comprises a slave power controller coupled to passive circuit components configured to convert a first dc voltage to a second dc voltage; and   a display configured to provide a user interface, the display comprising a master power controller and a display logic circuit, the display logic circuit being configured to control the display and being configured to receive the second dc voltage, the master power controller being operably coupled to the slave power controller to cause the slave power controller to switch the first dc voltage relative to the passive circuit components to generate the second dc voltage based at least in part on the power requirements of the display logic circuit.   
   
   
       10 . The handheld electronic device of  claim 9 , wherein the slave power controller comprises a slave switcher coupled to a slave switch, and wherein the master power controller comprises a master switcher coupled to a master switch, the master switch being operably coupled to the slave switcher; and
 wherein the master switcher is operable to switch the master switch on and off to alternatively enable and disable the slave switcher to cause the slave switcher to switch the slave switch on and off to cause the first dc voltage to be switched relative to the passive circuit components to generate the second dc voltage.   
   
   
       11 . The handheld electronic device of  claim 9 , wherein the power management unit is located separately from the display within the handheld electronic device. 
   
   
       12 . The handheld electronic device of  claim 9 , wherein the slave power controller is arranged relative to the passive components and an input for the first dc voltage to form one of a buck dc/dc voltage converter, a boost dc/dc voltage converter, or a fly back dc/dc voltage converter. 
   
   
       13 . The handheld electronic device of  claim 9 , wherein the master power controller receives from the display logic circuit a signal indicative of the power requirement of the display logic circuit and receives the second dc voltage as a feedback signal, and wherein the master power controller controls the slave power controller based at least in part on a comparison of the power requirement signal and the feedback signal. 
   
   
       14 . The handheld electronic device of  claim 9 , wherein the power management unit comprises filtering circuitry coupled between the master power controller and the slave power controller. 
   
   
       15 . A method of providing power to a sub-circuit, comprising:
 converting a first dc voltage to a second dc voltage using a slave dc/dc converter;   supplying the second dc voltage to a sub-circuit, the sub-circuit being operably coupled to a master power controller; and   transmitting a control signal from the master power controller to the slave dc/dc converter to cause the slave dc/dc converter to convert the first dc voltage to the second dc voltage based at least in part on the power requirements of the sub-circuit.   
   
   
       16 . The method of  claim 15 , wherein converting the first dc voltage to the second dc voltage comprises switching the first dc voltage relative to passive circuit components in the slave dc/dc converter. 
   
   
       17 . The method of  claim 15 , wherein transmitting the control signal comprises:
 transmitting a signal indicative of the power requirements of the sub-circuit to the master power controller;   transmitting the second dc voltage as a feedback signal to the master power controller; and   generating the control signal by the master power controller based at least in part on a comparison of the power requirements signal and the feedback signal.   
   
   
       18 . The method of  claim 15 , comprising filtering the control signal transmitted from the master power controller to the slave dc/dc converter. 
   
   
       19 . The method of  claim 15 , wherein transmitting the control signal comprises enabling and disabling the slave dc/dc converter to cause the slave dc/dc converter to cause the first dc voltage to be switched relative to passive components of the slave dc/dc converter. 
   
   
       20 . The method of  claim 15 , wherein converting the first dc voltage to the second dc voltage comprises adjusting the first dc voltage upwardly or downwardly.