Synchronous rectifying type switching regulator control circuit and semiconductor integrated circuit including the same
View Patent ↗A synchronous rectifying type switching regulator control circuit has a first reference voltage circuit that receives a soft start signal from a soft start circuit and outputs a first reference voltage. An error amplifying circuit amplifies a difference of the first reference voltage and a divided voltage from a voltage dividing circuit and outputs an error voltage Verr. A first comparing circuit compares a triangular wave from an oscillator with the error voltage Verr and outputs an output pulse Vcomp. A second comparing circuit compares a second reference voltage from a second reference voltage circuit with the error voltage Verr and outputs a voltage ERRcomp. A logic circuit receives the soft start signal, the output pulse Vcomp, and the voltage ERRcomp and outputs a voltage Vcomp2. The logic circuit outputs the output pulse Vcomp when the error voltage Verr is higher than the second reference voltage during a soft start period. A synchronous rectifying circuit outputs a drive signal for driving a switching element when the logic circuit outputs the output pulse Vcomp to the synchronous rectifying circuit in accordance with the soft start signal and the voltage ERRcomp.
1. A synchronous rectifying type switching regulator control circuit, comprising:
a soft start circuit that outputs a soft start signal;
a first reference voltage circuit that receives the soft start signal and outputs a first reference voltage;
a voltage dividing circuit that divides an output voltage and outputs a divided voltage;
an error amplifying circuit that amplifies a difference of the first reference voltage and the divided voltage and outputs an error voltage Verr;
an oscillator that outputs a triangular wave;
a first comparing circuit that compares the triangular wave with the error voltage Verr and outputs an output pulse Vcomp;
a second reference voltage circuit that outputs a second reference voltage;
a second comparing circuit that compares the second reference voltage with the error voltage Verr and outputs a voltage ERRcomp;
a logic circuit that receives the soft start signal, the output pulse Vcomp, and the voltage ERRcomp and outputs a voltage Vcomp 2 , and that outputs the output pulse Vcomp when the error voltage Verr is higher than the second reference voltage during a soft start period; and
a synchronous rectifying circuit that outputs a drive signal for driving a switching element when the logic circuit outputs the output pulse Vcomp to the synchronous rectifying circuit in accordance with the soft start signal and the voltage ERRcomp.
2. A synchronous rectifying type switching regulator control circuit according to claim 1 ; wherein the second reference voltage is within a range between maximal and minimal voltages of the output signal from the oscillator.
3. A semiconductor integrated circuit comprising the synchronous rectifying type switching regulator control circuit according to claim 1 .
4. A semiconductor integrated circuit comprising: a switching regulator; and a synchronous rectifying type switching regulator control circuit according to claim 1 that controls the switching regulator.
5. A synchronous rectifying type switching regulator control circuit, comprising:
a soft start circuit that outputs a soft start signal;
a first reference voltage circuit that receives the soft start signal and outputs a first reference voltage;
a voltage dividing circuit that divides an output voltage and outputs a divided voltage;
an error amplifying circuit that amplifies a difference of the first reference voltage and the divided voltage and outputs an error voltage Verr;
an oscillator that outputs a triangular wave;
a first comparing circuit that compares the triangular wave with the error voltage Verr and outputs an output pulse Vcomp;
a second reference voltage circuit that outputs a second reference voltage that is within a range between maximal and minimal voltages of the output signal from the oscillator;
a second comparing circuit that compares the second reference voltage with the error voltage Verr and outputs a voltage ERRcomp;
a logic circuit that receives the soft start signal, the output pulse Vcomp, and the voltage ERRcomp and outputs a voltage Vcomp 2 , and that outputs the output pulse Vcomp when the error voltage Verr is higher than the second reference voltage during a soft start period; and
a synchronous rectifying circuit that outputs a drive signal for driving a switching element when the logic circuit outputs the output pulse Vcomp to the synchronous rectifying circuit in accordance with the soft start signal and the voltage ERRcomp.
6. A semiconductor integrated circuit comprising the synchronous rectifying type switching regulator control circuit according to claim 5 .
7. A semiconductor integrated circuit comprising: a switching regulator; and a synchronous rectifying type switching regulator control circuit according to claim 5 that controls the switching regulator.