Topology for a positive buck-boost switching regulator
View Patent ↗A new topology for a buck-boost switching regulator is provided herein. Embodiments provide an efficient buck-boost switching regulator that provides a regulated output voltage from an unregulated input voltage. Embodiments include a buck-boost switching regulator topology, where the operating mode is determined separately from the pulse-width modulated (PWM) control signal. This topology, in one embodiment, provides a better transient response than typical buck-boost switching regulator topologies, where PWM control circuitry and operating mode circuitry are combined. Furthermore, embodiments provide a buck-boost switching regulator that allows for high efficiency when the output voltage is close to the input voltage.
1. A switching regulator for providing a regulated output voltage from an unregulated input voltage, the regulated output voltage being substantially equal to a reference voltage, the switching regulator comprising:
controller logic configured to provide a control signal having a duty-cycle that is a function of a feedback signal and the reference voltage;
a mode generator configured to provide a mode signal, the mode generator comprising:
a ramp generator configured to provide a fixed peak waveform;
a mode reference generator configured to provide a mode reference voltage based on a difference between the unregulated input voltage and the reference voltage; and
comparator circuitry configured to compare the fixed peak waveform and the mode reference voltage to provide the mode signal;
switching logic configured to receive the mode signal and the control signal and provide driving signals; and
a power switch arranged in a circuit and configured to be controlled by the driving signals.
2. The switching regulator of claim 1 , wherein the feedback signal is proportional to a current flowing through an inductor that is intermittently coupled between the unregulated input voltage and the regulated output voltage.
3. The switching regulator of claim 1 , wherein the feedback signal is proportional to the regulated output voltage.
4. The switching regulator of claim 1 , wherein the control signal is a pulse-width modulated signal.
5. The switching regulator of claim 1 , wherein the power switch is driven to operate in at least one of a buck mode, a boost mode, and a buck-boost mode.
6. The switching regulator of claim 1 , wherein the mode generator further comprises:
a one shot pulse circuit configured to receive the mode signal and provide a final mode signal that has a series of pulses, wherein each pulse corresponds to a transition of a pre-determined type within the initial mode signal.
7. The switching regulator of claim 6 , wherein the predetermined transition type of the one shot pulse circuit is a rising edge.
8. The switching regulator of claim 1 , wherein the fixed peak waveform is a sawtooth waveform.
9. A switching regulator for providing a regulated output voltage from an unregulated input voltage, the regulated output voltage being substantially equal to a reference voltage, the switching regulator comprising:
controller logic configured to provide a control signal having a duty-cycle that is a function of a feedback signal and the reference voltage;
a mode generator configured to provide a mode signal, the mode generator comprising:
a ramp generator configured to provide a fixed peak waveform;
a mode reference generator configured to provide a mode reference voltage based on a difference between the unregulated input voltage and the reference voltage; and
comparator circuitry configured to compare the fixed peak waveform and the mode reference voltage to provide the mode signal; and
switching logic configured to determine a driving signal based on a temporal relationship between a falling edge of the mode signal and a falling edge of the control signal.
10. The switching regulator of claim 9 , wherein the feedback signal is proportional to a current flowing through an inductor that is intermittently coupled between the unregulated input voltage and the regulated output voltage.
11. The switching regulator of claim 9 , wherein the feedback signal is proportional to the regulated output voltage.
12. The switching regulator of claim 9 , wherein the control signal is a pulse-width modulated signal.
13. The switching regulator of claim 9 , wherein the mode generator further comprises:
a one shot pulse circuit configured to receive the mode signal and provide a final mode signal that has a series of pulses, wherein each pulse corresponds to a transition of a pre-determined type within the initial mode signal.
14. The switching regulator of claim 13 , wherein the predetermined transition type of the one shot pulse circuit is a rising edge.
15. The switching regulator of claim 9 , wherein the fixed peak waveform is a sawtooth waveform.
16. The switching regulator of claim 9 , further comprising:
a power switch coupled between the unregulated input voltage and an inductor, the power switch configured to receive the driving signal.
17. The switching regulator of claim 9 , further comprising:
a power switch coupled between the regulated output voltage and an inductor, the power switch configured to receive the driving signal.