Feed-forward function for voltage mode control
An apparatus includes an input voltage, a comparator configured to generate a pulsed-width modulation signal based upon variation in the input voltage using a reference signal, and a switched mode power supply control circuit configured to control a power supply in voltage mode based at least upon the first pulsed-width modulation signal.
1. An apparatus, comprising:
an input voltage;
a first comparator configured to generate a first pulsed-width modulation signal based upon variation in the input voltage using a reference signal and send the first pulsed-width modulation signal to further elements of the apparatus;
a switched mode power supply (SMPS) control circuit, separate from the first comparator, configured to control a power supply in voltage mode based at least upon the first pulsed-width modulation signal;
an operational amplifier configured to generate an error signal based on a differential between output of the power supply and a reference voltage;
a signal generator circuit configured to generate a periodic signal based upon the first pulsed-width modulation signal; and
a second comparator configured to:
receive the error signal generated by the operational amplifier as a first input;
receive the periodic signal generated by the signal generator circuit as a second input; and
output a comparison of inputs of the second comparator to the SMPS control circuit.
2. The apparatus of claim 1 , wherein the first comparator is configured to adjust a duty cycle of the first pulsed-width modulation signal based upon the variation in the input voltage.
3. The apparatus of claim 1 , wherein the first comparator is configured to reduce a duty cycle of the first pulsed-width modulation signal based upon a positive variation in the input voltage.
4. The apparatus of claim 1 , wherein the first comparator is configured to raise a duty cycle of the first pulsed-width modulation signal based upon a negative variation in the input voltage.
5. The apparatus of claim 1 , wherein a duty cycle of the first pulsed-width modulation signal indicates the variation in the input voltage.
6. The apparatus of claim 1 , wherein the SMPS control circuit is configured to receive a second pulsed-width modulation signal on a falling edge input.
7. The apparatus of claim 1 , wherein the reference signal is a ramp signal generated according to a frequency at least as fast as the SMPS control circuit operation frequency.
8. The apparatus of claim 1 , wherein the signal generator circuit is further configured to:
generate the periodic signal based at least upon the first pulsed-width modulation signal, wherein the SMPS control circuit is configured to control the power supply further based at least upon the periodic signal; and
start the periodic signal sooner or later based upon the variation in the input voltage represented in the first pulsed-width modulation signal.
9. The apparatus of claim 8 , wherein the variation in the input voltage is represented by a duty cycle in the first pulsed-width modulation signal, and the signal generator circuit is further configured to start the periodic signal sooner or later using the duty cycle of the first pulsed-width modulation signal.
10. A microcontroller, comprising:
an input voltage;
a first comparator configured to generate a first pulsed-width modulation signal based upon variation in the input voltage using a reference signal and send the first pulsed-width modulation signal to further elements of the apparatus;
a switched mode power supply (SMPS) control circuit, separate from the first comparator, configured to control a power supply in voltage mode based at least upon the first pulsed-width modulation signal;
an operational amplifier configured to generate an error signal based on a differential between of the power supply and a reference voltage;
a signal generator circuit configured to generate a periodic signal based upon the first pulsed-width modulation signal; and
a second comparator configured to:
receive, at a first input of the second comparator, the error signal generated by the operational amplifier;
receive, at a second input of the second comparator, the periodic signal generated by the signal generator circuit; and
output a comparison of inputs of the second comparator to the SMPS control circuit.
11. The microcontroller of claim 10 , wherein the signal generator circuit is further configured to:
generate the periodic signal based at least upon the first pulsed-width modulation signal, wherein the SMPS control circuit is configured to control the power supply further based at least upon the periodic signal; and
start the periodic signal sooner or later based upon the variation in the input voltage represented in the first pulsed-width modulation signal.
12. A method, comprising:
receiving an input voltage;
generating a first pulsed-width modulation signal with a first comparator based upon variation in the input voltage using a reference signal;
with a switched mode power supply (SMPS) control circuit separate from the first comparator, controlling a power supply in voltage mode based at least upon the first pulsed-width modulation signal;
with an operational amplifier, generating an error signal based on a differential between output of the power supply and a reference voltage; with a signal generator circuit, generating a periodic signal based upon the first pulsed-width modulation signal; and with a second comparator: receiving the generated error signal; receiving the periodic signal generated by the signal generator circuit; and outputting a comparison of inputs of the second comparator to the (SMPS) control circuit.
13. The method of claim 12 , further comprising:
generating the periodic signal based at least upon the first pulsed-width modulation signal, wherein the SMPS control circuit is configured to control the power supply further based at least upon the periodic signal; and
starting the periodic signal sooner or later based upon the variation in the input voltage represented in the first pulsed-width modulation signal.
14. The method of claim 12 , further comprising adjusting a duty cycle of the first pulsed-width modulation signal based upon the variation in the input voltage.
15. The method of claim 12 , further comprising reducing a duty cycle of the first pulsed-width modulation signal based upon a positive variation in the input voltage.
16. The method of claim 12 , further comprising raising a duty cycle of the first pulsed-width modulation signal based upon a negative variation in the input voltage.
17. The method of claim 12 , wherein a duty cycle of the first pulsed-width modulation signal indicates the variation in the input voltage.
18. The method of claim 12 , wherein the reference signal is a ramp signal generated according to a frequency at least as fast as operation frequency of controlling the power supply.
19. The method of claim 12 , further comprising:
generating a periodic signal based upon the first pulsed-width modulation signal;
comparing an error in power output with the periodic signal;
generating a second pulsed-width modulation signal based on the comparison; and
providing the second pulsed-width modulation signal to the SMPS control circuit.
20. The method of claim 19 , further comprising receiving the second pulsed-width modulation signal on a falling edge input to generate an output signal.