CN-121643478-B - Conduction time generation circuit and voltage conversion system

CN121643478BCN 121643478 BCN121643478 BCN 121643478BCN-121643478-B

Abstract

The application provides a conduction time generation circuit and a voltage conversion system, and relates to the technical field of power electronics. The on-time generation circuit comprises a signal generation module, an output sampling module, a first comparator, a first output module and a second output module, wherein when the output sampling module outputs a turnover signal, the first output module outputs a start action signal to the signal generation module so that the signal generation module starts to act, the second output module starts to output an on-time signal after delay of the first comparator, and when the signal generation module outputs an end signal, the second output module ends to output the on-time signal, and the first output module and the second output module synchronously turn over. The on-time generating circuit and the voltage converting system provided by the application can enable the generated on-time to be more approximate to the on-time in an ideal state, reduce the influence of the delay of the comparator on the voltage converting circuit, and further improve the working performance of the voltage converting circuit.

Inventors

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Assignees

成都星拓微电子科技股份有限公司

Dates

Publication Date: 20260512
Application Date: 20260202

Claims (10)

1. A conduction time generation circuit is characterized by comprising a signal generation module, an output sampling module, a first comparator, a first output module and a second output module, wherein the output end of the signal generation module is respectively and electrically connected with the first input end of the first output module and the first input end of the second output module, the input end of the output sampling module is used for being connected with a voltage conversion circuit, the output end of the output sampling module is respectively and electrically connected with the second input end of the first output module and the input end of the first comparator, the output end of the first comparator is electrically connected with the second input end of the second output module, the output end of the first output module is electrically connected with the driving end of the signal generation module, the output end of the second output module is used as the output port of the conduction time generation circuit, When the output sampling module outputs a turnover signal, the first output module outputs a start action signal to the signal generating module so as to enable the signal generating module to start to act, and the second output module starts to output a conduction time signal after being delayed by the first comparator; When the signal generating module outputs the ending signal, the second output module ends outputting the on-time signal, and the first output module and the second output module synchronously turn over.
2. The on-time generation circuit of claim 1, wherein the signal generation module includes a second comparator, and the end signal generated by the signal generation module is output after being delayed by the second comparator; The delay of the first comparator is equal to the delay of the second comparator.
3. The on-time generation circuit of claim 2, wherein device parameters and operating parameters of the first comparator and the second comparator are consistent.
4. The on-time generation circuit of claim 3, wherein the first comparator and the second comparator are disposed in close proximity in a same direction.
5. The on-time generation circuit of claim 3, wherein the bias current of the first comparator is consistent with the bias current of the second comparator.
6. The on-time generation circuit of claim 1, wherein the signal generation module comprises a switching tube, a capacitor, a second comparator and a current source, one end of the capacitor is electrically connected with a first end of the switching tube, the current source and a non-inverting input end of the second comparator respectively, the other end of the capacitor is grounded with a second end of the switching tube, an inverting input end of the second comparator inputs a set voltage, an output end of the second comparator is electrically connected with a first input end of the first output module and a first input end of the second output module respectively, and an output end of the first output module is electrically connected with a driving end of the switching tube; when the first output module outputs a starting action signal, the switching tube is turned off.
7. The on-time generation circuit of claim 1, wherein the output sampling module comprises a third comparator, a non-inverting input of the third comparator is connected to a reference voltage source, an inverting input of the third comparator is connected to an output of the voltage conversion circuit, and an output of the third comparator is electrically connected to the non-inverting input of the first comparator and the second input of the first output module, respectively.
8. The on-time generation circuit of claim 1, wherein the first output module comprises a first inverter, a second inverter, a first nand gate, and a second nand gate, wherein an input of the first inverter is electrically connected to an output of the signal generation module, an input of the second inverter is electrically connected to the output sampling module, two input of the first nand gate and the second nand gate after cross coupling are electrically connected to the output of the first inverter and the output of the second inverter, respectively, and an output of the first nand gate and the second nand gate after cross coupling is electrically connected to a driving end of the signal generation module.
9. The on-time generation circuit of claim 1, wherein the second output module comprises a third inverter, a fourth inverter, a third nand gate, and a fourth nand gate, wherein an input of the third inverter is electrically connected to an output of the signal generation module, an input of the fourth inverter is electrically connected to an output of the first comparator, two input terminals of the third nand gate and the fourth nand gate after cross coupling are respectively electrically connected to the output terminals of the third inverter and the fourth inverter, and an output terminal of the third nand gate and the fourth nand gate after cross coupling are used as an output port of the on-time generation circuit.
10. A voltage conversion system, characterized in that the voltage conversion system comprises a voltage conversion circuit, a driving module and a conduction time generation circuit according to any one of claims 1 to 9, an output port of the conduction time generation circuit is electrically connected with the driving module, the driving module is electrically connected with a driving end of the voltage conversion circuit, and an output end of the voltage conversion circuit is electrically connected with the output sampling module.

Description

Conduction time generation circuit and voltage conversion system Technical Field The application relates to the technical field of power electronics, in particular to a conduction time generation circuit and a voltage conversion system. Background COT (Constant On-Time) is a variation of hysteresis Control (HYSTERETIC CONTROL) or Boundary Control (bound Control), which opens the upper tube and holds for a fixed period of Time (TON) whenever the output voltage is low to a certain threshold, then turns it off, after which the system waits for the output voltage to drop again to the threshold, and repeats the process. Unlike fixed frequency PWM control, COT control has no fixed on-clock, the on-time of each cycle is triggered by a "valley" of the output voltage, and the off-time is fixed (determined by TON). In the BUCK circuit with the COT structure, in an ideal state, the generating logic of the switching frequency FSW is that the circuit module generates the on-time TON, and then the negative feedback system generates the switching period T, t=ton/D (D is the duty cycle, d=vout/VIN), and the switching frequency fsw=1/T. For switching frequency stabilization, ton=k×d is generally set, K is a set coefficient, and fsw=1/K. At present, the COT structure in the BUCK circuit is generally built by a switch tube, a capacitor, a current source and a comparator, so that in practical application, the on-time TON is affected by the delay of the comparator. Specifically, in calculating the on-time, the delay needs to be added, i.e., ton=k×d+td1, TD1 representing the delay of the comparator. TD1 is a delay caused by a specific characteristic of the comparator, and is generally a constant of 20 ns-30 ns. The influence degree of TD1 on the switching frequency is different, and even trimming is unavoidable. The effect of TD1 is more and more pronounced in high frequency and small duty cycle applications. In the BUCK circuit, the inductance can be reduced by increasing the switching frequency while the output ripple is reduced, so the BUCK circuit needs to operate at a higher frequency. In summary, in the conventional BUCK circuit with the COT structure, the delay of the comparator in the COT structure affects the operation performance of the BUCK circuit, such as the accuracy of the switching frequency. Disclosure of Invention The application aims to provide a turn-on time generating circuit and a voltage conversion system, which are used for solving the problem that the working performance of a BUCK circuit is influenced by the delay of a comparator in the prior art. In order to achieve the above object, the technical scheme adopted by the embodiment of the application is as follows: In one aspect, the embodiment of the application provides a conduction time generation circuit, which comprises a signal generation module, an output sampling module, a first comparator, a first output module and a second output module, wherein the output end of the signal generation module is respectively and electrically connected with the first input end of the first output module and the first input end of the second output module, the input end of the output sampling module is used for being connected with a voltage conversion circuit, the output end of the output sampling module is respectively and electrically connected with the second input end of the first output module and the input end of the first comparator, the output end of the first comparator is electrically connected with the second input end of the second output module, the output end of the first output module is electrically connected with the driving end of the signal generation module, and the output end of the second output module is used as the output port of the conduction time generation circuit, When the output sampling module outputs a turnover signal, the first output module outputs a start action signal to the signal generating module so as to enable the signal generating module to start to act, and the second output module starts to output a conduction time signal after being delayed by the first comparator; When the signal generating module outputs the ending signal, the second output module ends outputting the on-time signal, and the first output module and the second output module synchronously turn over. Optionally, the signal generating module includes a second comparator, and the end signal generated by the signal generating module is output after being delayed by the second comparator; The delay of the first comparator is equal to the delay of the second comparator. Optionally, the device parameters and the working parameters of the first comparator and the second comparator are consistent. Optionally, the first comparator and the second comparator are disposed nearby in the same direction. Optionally, the bias currents of the first comparator and the second comparator are identical. Optionally, the signal generating module includes a switch tube, a capac