CONTROL CIRCUIT FOR BUCK-BOOST POWER CONVERTER WITH SEAMLESS MODE TRANSITION CONTROL

摘要

A buck-boost power converter and a control circuit for the buck-boost converter. The control circuit includes a buck cycle pulse width modulation module and a boost cycle pulse width modulation module respectively having a first controllable hysteresis and a second controllable hysteresis. The buck cycle pulse width modulation module can regulate the first controllable hysteresis during the buck-boost power converter transits between a buck mode and a buck-boost mode so as to eliminate or at least reduce sparks in an output voltage. The boost cycle pulse width modulation module can regulate the second controllable hysteresis during the buck-boost power converter transits between the buck-boost mode and a boost mode so as to eliminate or at least reduce sparks in the output voltage.

主权项

1. A control circuit for regulating a buck-boost power converter, comprising:
an operational amplifier configured to receive a first feedback signal indicative of an output voltage of the buck-boost power converter and a reference signal, and further configured to conduct operation to the first feedback signal and the reference signal to provide an amplified difference signal indicative of a difference between the first feedback signal and the reference signal; a buck cycle pulse width modulation module configured to respectively receive the amplified difference signal and a first current sensing signal indicative of a switching current during a buck cycle of the buck-boost power converter, and to compare the first current sensing signal with the amplified difference signal to generate a first pulse width modulation signal for regulating a buck duty cycle of the buck-boost power converter, wherein the buck cycle pulse width modulation module has a first controllable hysteresis and a hysteresis control terminal which is configured to receive a first mode transition control signal, and wherein the buck cycle pulse width modulation module is further configured to enable the first controllable hysteresis in response to the first mode transition control signal when the buck-boost power converter transits from the buck mode to the buck-boost mode, and to disable the first controllable hysteresis in response to the first mode transition control signal when the buck-boost power converter transits from the buck-boost mode to the buck mode; and a boost cycle pulse width modulation module configured to respectively receive the amplified difference signal and a second current sensing signal indicative of a switching current during a boost cycle of the buck-boost power converter, and to compare the second current sensing signal with the amplified difference signal to generate a second pulse width modulation signal for regulating a boost duty cycle of the buck-boost power converter, wherein the boost cycle pulse width modulation module has a second controllable hysteresis and a hysteresis control terminal which is configured to receive a second mode transition control signal, and wherein the boost cycle pulse width modulation module is further configured to enable the second controllable hysteresis in response to the second mode transition control signal when the buck-boost power converter transits from the buck-boost mode to the boost mode, and to disable the second controllable hysteresis in response to the second mode transition control signal when the buck-boost power converter transits from the boost mode to the buck-boost mode.