Systems and methods for providing intelligent constant on-time control
A system that provides intelligent constant on-time control may include a first switch coupled to a power input; a second switch coupled to the first switch; a switching node between the first switch and the second switch, the switching node configured to be connected to an inductor and a power output; feedback paths coupled to (1) a synthesized node and (2) the power output, the feedback paths enabling feedback of signals from (1) the synthesized node, and (2) the power output; and a controller coupled to the feedback paths. The controller may be configured to control a voltage at the power output based on a combination of the signals carried by the feedback paths.
1. A system that provides intelligent constant on-time control, comprising:
a first switch coupled to a power input node, wherein the first switch operates according to a first control signal;
a second switch coupled to the first switch, wherein the second switch operates according to a second control signal;
a switching node between the first switch and the second switch, the switching node connected through an inductor to a power output node;
an inductor current emulator comprising:
a first current source configured to provide a first current, wherein the first current is proportional to a product of a constant and a voltage at the power input node,
a second current source configured to provide a second current, wherein the second current is proportional to a product of the constant and a voltage at the power output node,
a synthesized node coupled between the first current source and the second current source, and
a controller configured to provide the first control signal and the second control signal based on a control voltage that includes an AC component of the voltage at the synthesized node, and excludes a DC component of the voltage at the synthesized node.
2. The system of claim 1 , wherein:
the control voltage includes a DC component of the voltage at the power output node.
3. The system of claim 2 , wherein:
the control voltage excludes an AC component of the voltage at the power output node.
4. The system of claim 1 , wherein the inductor current emulator further comprises:
a third switch coupled between the first current source and the synthesized node, wherein the third switch operates according to the first control signal.
5. The system of claim 1 , wherein:
the controller controls an on-time of the first switch by digitally changing a capacitance value, a current mirror ratio or a threshold voltage of the system via a phase-locked loop.
6. The system of claim 5 , wherein:
the phase-locked loop includes a sequential phase detector, a state machine, and an n-bit bi-direction counter.
7. The system of claim 1 , further comprising:
a capacitor coupled in parallel with the second current source.
8. The system of claim 1 , further comprising:
a capacitor coupled between the synthesized node and the controller.
9. The system of claim 1 , further comprising:
a first resistor coupled between the power output node and the synthesized node.
10. The system of claim 9 , further comprising:
a second resistor coupled between the synthesized node and ground.
11. The system of claim 1 , further comprising:
a resistor coupled between the inductor and the power output node.
12. The system of claim 1 , further comprising:
a resistor coupled between the synthesized node and a bias voltage source.
13. The system of claim 1 , further comprising:
a first diode coupled in parallel with the first switch; and
a second diode coupled in parallel with the second switch.
14. The system of claim 1 , further comprising:
a resistor coupled to the power output node; and
a capacitor coupled between the resistor and ground.
15. A method for providing intelligent constant on-time control for a system comprising:
a first switch coupled to a power input node;
a second switch coupled to the first switch;
a switching node between the first switch and the second switch, the switching node connected through an inductor to a power output node; and feedback paths coupled to (1) a synthesized node and (2) the power output, the feedback paths enabling feedback of signals from (1) the synthesized node, and (2) the power output, the method comprising:
generating a first current with a first current source, wherein the first current source is coupled to the synthesized node, and wherein the first current is proportional to a product of a constant and a voltage at the power input node;
providing a second current to the synthesized node with a second current source, wherein the second current is proportional to a product of the constant and a voltage at the power output node;
providing a first control signal and a second control signal based on a control voltage that includes an AC component of the voltage at the synthesized node, and excludes a DC component of the voltage at the synthesized node;
controlling the first switch with the first control signal; and
controlling the second switch with the second control signal.
16. The method of claim 15 , wherein:
the control voltage includes a DC component of the voltage at the power output node.
17. The method of claim 16 , wherein:
the control voltage excludes an AC component of the voltage at the power output node.
18. The method of claim 15 , wherein:
the system comprises a third switch coupled between the first current source and the synthesized node; and
the method further comprises operating the third switch according to the first control signal.
19. The method of claim 15 , further comprising:
controlling an on-time of the first switch by digitally changing a capacitance value, a current mirror ratio, or a threshold voltage of a phase-locked loop.
20. The method of claim 19 , wherein:
the phase-locked loop includes a sequential phase detector, a state machine, and an n-bit bi-direction counter.