Input power limited switching regulator
This disclosure describes a system and a method to limit (i.e., regulate) the input power of a power converter as a function of the voltage and/or loading condition of a power-limited source such as a battery. In some embodiments, the power converter may comprise a transconductance amplifier that may produce a sink current to a current mirror, which in turn that may provide an adjusted current limit threshold to the power converter. The power converter may utilize the current limit threshold to perform cycle-by-cycle current limiting, thus regulating the input power drawn from the battery.
1. A power converter, comprising:
a main power circuit configured to produce an output voltage from a battery;
a regulator controller configured to produce a command signal based on the input voltage and a reference voltage, wherein the reference voltage is adjustable based on one or more of an age or a temperature of the battery and wherein the reference voltage is adjusted so as to limit voltage sag of the input voltage; and
a current regulator configured to produce a current limit threshold based on the command signal,
wherein the main power circuit is configured to limit an input power received from the power-limited input voltage source based on the adjusted current limit threshold.
2. The power converter of claim 1 , wherein the regulator controller comprises a transconductance amplifier configured to produce the command signal as a sink current based on the input voltage and the reference voltage.
3. The power converter of claim 1 , wherein the main power circuit is further configured to limit the input power on a cycle-by-cycle basis.
4. The power converter of claim 1 , wherein the main power circuit comprises a boost converter.
5. The power converter of claim 1 , wherein the main power circuit comprises a buck converter.
6. The power converter of claim 1 , wherein the reference voltage is adjustable based on an age of the power-limited input voltage source.
7. The power converter of claim 2 , wherein the current regulator comprises a current mirror configured to produce the current limit threshold based on the sink current.
8. The power converter of claim 2 , wherein the transconductance amplifier has an adjustable gain that is adjusted based on the input voltage of the power converter.
9. The power converter of claim 6 , wherein the reference voltage is adjustable based on an age and a temperature of the power-limited input voltage source.
10. The power converter of claim 7 , wherein the current mirror comprises one or more transistors.
11. A method for limiting an input power of a battery-powered power converter, the method comprising:
using a throttle controller to provide a command signal based on an input voltage of the power converter and a reference voltage, wherein the reference voltage is adjustable based on at least one of an age or a temperature of the battery and is adjusted so as to limit voltage sag of the input voltage;
using a current regulator to provide an adjusted current limit threshold based on the command signal; and
limiting an input power of the power converter based on the adjusted current limit threshold.
12. The method of claim 11 , wherein the throttle controller comprises a transconductance amplifier.
13. The method of claim 11 , wherein limiting the input power of the power converter comprises performing cycle-by-cycle current limiting based on the current limit threshold.
14. The method of claim 11 , wherein the power converter comprises a buck converter.
15. The method of claim 11 , wherein the power converter comprises a boost converter.
16. The method of claim 11 , wherein the reference voltage is adjustable based on an age of the power-limited source.
17. The method of claim 12 , wherein the current regulator comprises a current mirror.
18. The method of claim 12 , wherein the transconductance amplifier is configured to have an adjustable gain based on the input voltage of the power converter.
19. The method of claim 16 , wherein the reference voltage is adjustable based on an age and a temperature of the power-limited source.
20. The method of claim 17 , wherein the current mirror comprises one or more transistors.
21. A power converter comprising:
an input configured to receive an input voltage from a battery;
an inductor and a plurality of switching devices coupled between the input and an output of the power converter;
a switch controller coupled to the plurality of switching devices and configured to operate the switching devices to produce an output voltage from the input voltage; and
a current limiting circuit having a current regulator and a regulator controller, the current limiting circuit being coupled to the switch controller and configured to limit input power by causing the switch controller to modify operation of one or more of the plurality of switching devices responsive to a comparison between the input voltage and a reference voltage, wherein the reference voltage is adjustable based on one or more of an age or a temperature of the battery and wherein the reference voltage is adjusted so as to limit voltage sag of the input voltage.
22. The power converter of claim 21 , wherein the reference voltage is adjustable based on an age of the power-limited input voltage source.
23. The power converter of claim 22 , wherein the reference voltage is adjustable based on an age and a temperature of the power-limited input voltage source.