Magnitude adjustment of the drive signal of a switching transistor of a switching power converter
View Patent ↗The drive current of the switch in a switching power converter is adjusted dynamically according to line or load conditions within a switching cycle and/or over a plurality of switching cycles. The magnitude of the switch drive current can be dynamically adjusted within a switching cycle and/or over a plurality of switching cycles, in addition to the pulse widths or pulse frequencies of the switch drive current.
1. A switching power converter comprising:
a magnetic component coupled between a power source and a load;
a switch coupled to the magnetic component for coupling or decoupling the load to or from the power source through the magnetic component; and
a switch controller coupled to the switch, the switch controller generating an output drive signal that alternates between a first logic state and a second logic state, the first logic state defining an on-time of the switch and the second logic state defining an off-time of the switch;
wherein the switch controller further generates a switch drive signal that is transmitted to the switch for turning on the switch while the output drive signal is at the first logic state and for turning off the switch while the output drive signal is at the second logic state, the switch controller adjusting a current magnitude or a voltage magnitude of the switch drive signal while the output drive signal is at the first logic state, the current magnitude or the voltage magnitude of the switch drive signal adjusted to be zero for a predetermined period of time at an end of the on-time of the switch while the output drive signal is at the first logic state.
2. The switching power converter of claim 1 , wherein the switch controller includes:
a pulse generator generating the output drive signal that alternates between the first logic state and the second logic state; and
a dynamic switch drive module receiving the output drive signal and dynamically adjusting the magnitude of the switch drive signal while the output drive signal is at the first logic state.
3. The switching power converter of claim 1 , wherein the dynamic switch drive module adjusts the magnitude of the switch drive signal to be at a predetermined level for a predetermined period of time at a beginning of the on-time of the switch while the output drive signal is at the first logic state.
4. The switching power converter of claim 3 , wherein the predetermined period of time is fixed according to device characteristics of one or more components of the switching power converter.
5. The switching power converter of claim 1 , wherein the switch is a bipolar junction transistor and the switch drive signal is a base current of the bipolar junction transistor, and the dynamic switch drive module adjusts the magnitude of the base current to be substantially proportional to a collector current of the bipolar junction transistor.
6. The switching power converter of claim 5 , wherein the magnitude of the switch drive signal is adjusted based on an input voltage to the switching power converter and the load of the switching power converter.
7. The switching power converter of claim 1 , wherein the predetermined period of time during which the switch drive signal is zero is determined based on an input voltage to the switching power converter and the load of the switching power converter.
8. The switching power converter of claim 2 , wherein the dynamic switch drive module comprises:
a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the on-time of the switch while the output drive signal is at the first logic state; and
a switch multiplex receiving a plurality of reference current inputs and generating the switch drive signal as a current signal, the magnitude of the switch drive current signal corresponding to a magnitude of the digital switch drive control signal.
9. The switching power converter of claim 8 , wherein the plurality of reference current inputs include different weighted magnitudes of reference current.
10. The switching power converter of claim 9 , wherein the plurality of reference current inputs are determined by a single resistor.
11. The switching power converter of claim 2 , wherein the dynamic switch drive module comprises:
a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the on-time of the switch while the output drive signal is at the first logic state; and
a switch multiplex receiving a plurality of reference voltage inputs and generating the switch drive signal as a voltage signal, the magnitude of the switch drive voltage signal corresponding to a magnitude of the digital switch drive control signal.
12. The switching power converter of claim 11 , wherein the plurality of reference voltage inputs include different weighted magnitudes of reference voltages.
13. The switching power converter of claim 2 , wherein the dynamic switch drive module comprises:
a switch drive control signal generator generating a digital switch drive control signal that is dynamically adjusted within the on-time of the switch while the output drive signal is at the first logic state; and
a switch multiplex receiving a plurality of reference resistance inputs and generating the switch drive signal as a voltage signal, the magnitude of the switch drive voltage signal corresponding to a magnitude of the digital switch drive control signal.
14. The switching power converter of claim 13 , wherein the plurality of reference voltage inputs include different weighted resistances of a plurality of resistors.
15. The switching power converter of claim 1 , wherein the switch is a bipolar junction transistor and the switch drive signal is a base current of the bipolar junction transistor, and the switching power converter further comprises another transistor coupled to the base of the bipolar junction transistor, said another transistor being configured to be turned on while the bipolar junction transistor is turned off to provide a discharge path for charges on the base of the bipolar junction transistor.
16. The switching power converter of claim 1 , wherein the switch controller adjusts the on-time of the switch in addition to dynamically adjusting the magnitude of the switch drive signal during the on-time of the switch while the output drive signal is at the first logic state.
17. The switching power converter of claim 1 , wherein the switch controller dynamically adjusts the magnitude of the switch drive signal over the on-time of the switch and a subsequent on-time of the switch.
18. The switching power converter of claim 1 , wherein the switch is a bipolar junction transistor and the switching power converter further comprises a comparator including:
a first input receiving a base voltage at a base of the bipolar junction transistor;
a second input receiving a reference voltage corresponding to when the bipolar junction transistor is off; and
an output generating an output signal based upon a comparison of the base voltage to the reference voltage, the output signal transitioning from a first logic state to a second logic state indicating when the bipolar junction transistor actually turned off.
19. The switching power converter of claim 1 , wherein the switch controller is further configured to adjust the current magnitude or the voltage magnitude from a first level to a second level during the on-time of the switch while the output drive signal is at the first logic state.
20. A switching power converter comprising:
a magnetic component coupled between a power source and a load;
a switch coupled to the magnetic component for coupling or decoupling the load to or from the power source through the magnetic component; and
a switch controller coupled to the switch, the switch controller generating an output drive signal that alternates between a first logic state and a second logic state, the first logic state defining an on-time of the switch, and the second level defining an off-time of the switch;
wherein the switch controller further generates a switch drive signal that is transmitted to the switch for turning on the switch while the output drive signal is at the first logic state and for generating the switch drive signal to turn off the switch while the output drive signal is at the second logic state, the switch controller adjusting a current magnitude or a voltage magnitude of the switch drive signal while the output drive signal is at the second logic state defining the off-time of the switch.