Control circuit and control method for switch circuit and switching-mode power supply circuit
First Claim
1. A control method for a switch circuit, comprising following steps:
- detecting an output voltage or output current in a circuit, and increasing an upper limit value and a lower limit value of an inductor current when the output voltage is lower than a preset reference voltage or the output current is lower than a preset reference current; and
decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage or the output current is higher than the preset reference current; and
sampling the inductor current in the circuit to obtain a sampling current, and controlling a main switch transistor in the circuit to be switched off when the sampling current rises to the upper limit value of the inductor current; and
controlling the main switch transistor to be switched on when the sampling current drops to the lower limit value of the inductor current;
wherein detecting the output voltage or the output current in the circuit, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage or the output current is lower than the preset reference current, and decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage or the output current is higher than the preset reference current comprise the following steps;
detecting the output voltage in a switch circuit of a constant voltage output, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage; and
decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage; and
detecting the output current in a switch circuit of a constant current output, and increasing the upper limit value and the lower limit value of the inductor current when the output current is lower than the preset reference current; and
decreasing the upper limit value and the lower limit value of the inductor current when the output current is higher than the preset reference current;
wherein detecting the output voltage in the switch circuit of the constant voltage output, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage, and decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage comprise the following steps;
acquiring a sampling voltage of the output voltage in real time;
comparing the sampling voltage with the preset reference voltage, and obtaining a compensation voltage according to a comparison result;
converting the compensation voltage to obtain a command current; and
adjusting the upper limit value and the lower limit value of the inductor current according to a preset compensation current value and the command current;
wherein converting a compensation voltage to obtain a command current, adjusting a lower limit value of an inductor current according to the command current, the lower limit value of an inductor current plus a preset compensation current value to obtain the upper limit value of an inductor current, the switching frequency can be controlled by controlling the preset compensation current to achieve fixed frequency.
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Abstract
The present invention provides a control circuit and a control method for a switch circuit and a switching-mode power supply circuit. The control method comprises following steps: detecting an output voltage or an output current, and adjusting an upper limit value and a lower limit value of an inductor current according to a result of comparing the output voltage or the output current with the corresponding reference; and sampling the inductor current, and controlling a main switch transistor in the circuit to be switched off when a sampling current rises to the upper limit value, and controlling the main switch transistor to be switched on when the sampling current drops to the lower limit value. In the present invention, the inductor current is fast in response without overshoot, the output voltage drops very little, there is no overshoot in a process of voltage recovery, and circuit transient response is fast.
6 Citations
13 Claims
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1. A control method for a switch circuit, comprising following steps:
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detecting an output voltage or output current in a circuit, and increasing an upper limit value and a lower limit value of an inductor current when the output voltage is lower than a preset reference voltage or the output current is lower than a preset reference current; and
decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage or the output current is higher than the preset reference current; andsampling the inductor current in the circuit to obtain a sampling current, and controlling a main switch transistor in the circuit to be switched off when the sampling current rises to the upper limit value of the inductor current; and
controlling the main switch transistor to be switched on when the sampling current drops to the lower limit value of the inductor current;wherein detecting the output voltage or the output current in the circuit, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage or the output current is lower than the preset reference current, and decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage or the output current is higher than the preset reference current comprise the following steps; detecting the output voltage in a switch circuit of a constant voltage output, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage; and
decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage; anddetecting the output current in a switch circuit of a constant current output, and increasing the upper limit value and the lower limit value of the inductor current when the output current is lower than the preset reference current; and
decreasing the upper limit value and the lower limit value of the inductor current when the output current is higher than the preset reference current;wherein detecting the output voltage in the switch circuit of the constant voltage output, and increasing the upper limit value and the lower limit value of the inductor current when the output voltage is lower than the preset reference voltage, and decreasing the upper limit value and the lower limit value of the inductor current when the output voltage is higher than the preset reference voltage comprise the following steps; acquiring a sampling voltage of the output voltage in real time; comparing the sampling voltage with the preset reference voltage, and obtaining a compensation voltage according to a comparison result; converting the compensation voltage to obtain a command current; and adjusting the upper limit value and the lower limit value of the inductor current according to a preset compensation current value and the command current; wherein converting a compensation voltage to obtain a command current, adjusting a lower limit value of an inductor current according to the command current, the lower limit value of an inductor current plus a preset compensation current value to obtain the upper limit value of an inductor current, the switching frequency can be controlled by controlling the preset compensation current to achieve fixed frequency. - View Dependent Claims (2, 3, 4)
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5. A control circuit for a switch circuit, comprising a command current acquiring circuit, an adjuster, an inductor current control circuit, and a drive circuit;
- wherein
the command current acquiring circuit is configured to detect an output voltage or an output current in a circuit, convert the output voltage or the output current into a command current, and output the command current to the adjuster; the adjuster is configured to adjust an upper limit value or a lower limit value of an inductor current according to the command current and a preset compensation current value; and the inductor current control circuit is connected with the adjuster, the drive circuit, and a sampling terminal of the inductor current;
the inductor current control circuit is configured to sample the inductor current to obtain a sampling current, generate a switching signal according to the sampling current and the upper limit value and the lower limit value of the inductor current, and control a main switch transistor by the drive circuit, the main switch transistor is controlled to be switched off when the sampling current rises to the upper limit value of the inductor current, and the main switch transistor is controlled to be switched on when the sampling current drops to the lower limit value of the inductor current;wherein converting a compensation voltage to obtain a command current, adjusting a lower limit value of an inductor current according to the command current, the lower limit value of an inductor current plus a preset compensation current value to obtain the upper limit value of an inductor current, the switching frequency can be controlled by controlling the preset compensation current to achieve fixed frequency. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12, 13)
- wherein
Specification