Method and apparatus for measuring an average output current of a switching regulator using current-sensing-circuitry
One embodiment of the present invention provides an apparatus that measures the average-output-current produced by a switching regulator within an electronic device. The apparatus includes current-sensing-circuitry coupled to a switching field-effect-transistor (FET) within the switching regulator, wherein the current-sensing-circuitry is configured to bypass a small sense current from the conducting current of the switching-FET according to a sense ratio, wherein the conducting current is controlled by a control signal for the switching regulator. The apparatus also includes a current-to-voltage-converter coupled to the current-sensing-circuitry which is configured to convert the sense current into a sense voltage. The apparatus further includes voltage-averaging-circuitry which is configured to produce an average-sense-voltage from the sense voltage. This sense voltage is coupled to the input of the voltage-average-circuitry through a switch, which is gated by the control signal. The average-output-current of the switching regulator is indicated by the average-sense-voltage.
1. An apparatus that measures an average-output-current produced by a switching regulator within an electronic device, comprising:
current-sensing-circuitry coupled to a switching field-effect-transistor (FET) within the switching regulator, wherein the current-sensing-circuitry is configured to bypass a small sense current from the conducting current of the switching-FET according to a sense ratio, wherein the conducting current is controlled by a control signal for the switching regulator;
a current-to-voltage-converter coupled to the current-sensing-circuitry configured to convert the sense current into a sense voltage; and
voltage-averaging-circuitry configured to produce an average-sense-voltage from the sense voltage,
wherein the sense voltage is coupled to the input of the voltage-average-circuitry through a switch; and
wherein the switch is gated by the control signal which is directly connected to the switch;
wherein the average-output-current of the switching regulator is indicated by the average-sense-voltage.
2. The apparatus of claim 1 , wherein the current-sensing-circuitry includes a sense FET coupled in parallel with a low-side switching FET in the switching regulator.
3. The apparatus of claim 2 , wherein the current-to-voltage converter is configured to provide both the sense FET and the low-side switching FET with the same voltage.
4. The apparatus of claim 1 , wherein the voltage-averaging-circuitry includes a track-and-hold circuit.
5. The apparatus of claim 1 , wherein the voltage-average-circuitry is configured to average the sense voltage input when the switch is activated by the control signal and is configured to maintain the average-sense-voltage when the switch is deactivated by the control signal, thereby facilitating tracking of the average-sense-voltage during a period of the control signal.
6. The apparatus of claim 1 , wherein the average-output-current is used to determine power consumption of the electronic device.
7. The apparatus of claim 1 , wherein the current-sensing-circuitry, the current-to-voltage-converter, and the voltage-averaging-circuitry are integrated onto an integrated circuit chip.
8. The apparatus of claim 1 , wherein the current-to-voltage-converter and the voltage-averaging-circuitry are integrated onto an integrated circuit chip.
9. A method for measuring an average-output-current produced by a switching regulator within an electronic device, comprising:
using current-sensing-circuitry which is coupled to a switching field-effect-transistor (FET) within the switching regulator to bypass a small sense current from the conducting current of the switching-FET according to a sense ratio, wherein the conducting current is controlled by a control signal for the switching regulator;
converting the sense current into a sense voltage using a current-to-voltage-converter coupled to the current-sensing-circuitry; and
producing an average-sense-voltage from the sense voltage using voltage-averaging-circuitry,
wherein the sense voltage is coupled to the input of the voltage-average-circuitry through a switch; and
wherein the switch is gated by the control signal which is directly connected to the switch;
wherein the average-output-current of the switching regulator is indicated by the average-sense-voltage.
10. The method of claim 9 , wherein the current-sensing-circuitry includes a sense FET coupled in parallel with a low-side switching FET in the switching regulator.
11. The method of claim 10 , wherein the current-to-voltage converter is configured to provide both the sense FET and the low-side switching FET with the same voltage.
12. The method of claim 9 , wherein the voltage-averaging-circuitry includes a track-and-hold circuit.
13. The method of claim 9 , further comprising:
averaging the sense voltage input using the voltage-average-circuitry when the switch is activated by the control signal; and
maintaining the average-sense-voltage using the voltage-average-circuitry when the switch is deactivated by the control signal,
thereby facilitating tracking of the average-sense-voltage during a period of the control signal.
14. The method of claim 9 , further comprising determining a power consumption of the electronic device based on the average-output-current.
15. The method of claim 9 , wherein the current-sensing circuitry, the current-to-voltage-converter, and the voltage-averaging-circuitry are integrated onto an integrated circuit chip.
16. The method of claim 9 , wherein the current-to-voltage converter and the voltage-averaging-circuitry are integrated onto an integrated circuit chip.