A DC switching power supply and its fast transient response circuit

Abstract

The invention discloses a direct current switching power supply and a fast transient response circuit thereof. The circuit comprises an output dynamic detection module and a comparator, wherein the input end of the output dynamic detection module is connected to the output end of a driving module of the direct current switching power supply, the output end of the output dynamic detection module is connected to the input end of the comparator, the output dynamic detection module is used to obtain the output end voltage of the driving module, and outputs a control signal when a voltage drop of the output end is detected; the input end of the comparator is connected to the output end of the output dynamic detection module, and is used to obtain the output control signal of the output dynamic detection module; the output end of the comparator is connected to the logic module of the direct current switching power supply, the comparator is used to obtain the control current according to the output control signal, compare the control current with the current reference value, and output an effective forced driving signal, which is used to force the logic module to output an effective duty cycle signal to the driving module, so as to force the driving module to open, thereby ensuring that the output voltage does not drop significantly.

Description

Technical Field

[0001] The invention relates to the field of microelectronic technology, and in particular to a direct current switching power supply and a fast transient response circuit thereof. Background Art

[0002] In the prior art, a DC switching power supply includes a logic module and a driving module connected in sequence, wherein the output end of the driving module is connected to an output capacitor and a load respectively, and a power tube is connected in series in the driving module, and the power tube is used to control the charging and discharging of the output capacitor. In order to realize the control of the power tube, the logic module is used to output a duty cycle signal Duty, and send the duty cycle signal Duty to the driving module, and the driving module is used to control the conduction and closing of the power tube according to the duty cycle signal Duty.

[0003] The disadvantage of the above DC switching power supply is that when the load undergoes a transient jump, for example, when the load suddenly changes from no-load to full-load, the waveforms of the load current, the duty cycle signal Duty and the output voltage VOUT (the terminal voltage of the output capacitor) are as follows: Figure 1 As shown in the figure, it can be seen that when the duty cycle signal Duty is at a high level, it indicates that the output capacitor Cout replenishes energy. Taking the output capacitor Cout as 14uF as an example, without considering the piezoelectric effect, when the load current jumps from 0.5mA to 1A within 1us, the output voltage VOUT drops by about 84mV ( Figure 1 Therefore, how to quickly suppress the output voltage drop caused by the transient jump of the load connected to the output end of the DC switching power supply is a problem that needs to be solved urgently. Summary of the invention

[0004] Based on this, it is necessary to provide a DC switching power supply and a fast transient response circuit thereof to address the above technical problems, so as to solve the problem of large output voltage drop caused by transient jump of the load connected to the output end of the DC switching power supply in the prior art.

[0005] Based on the above purpose, a fast transient response circuit of a DC switching power supply includes:

[0006] An output dynamic detection module and a comparator, wherein the input end of the output dynamic detection module is used to connect to the output end of the driving module of the DC switching power supply, the output end of the output dynamic detection module is connected to the input end of the comparator, and the output dynamic detection module is used to obtain the output end voltage of the driving module and output a control signal when detecting that the output end voltage drops;

[0007] The input end of the comparator is connected to the output end of the output dynamic detection module, and is used to obtain the output control signal of the output dynamic detection module. The output end of the comparator is connected to the logic module of the DC switching power supply. The comparator is used to obtain the control current according to the output control signal, compare the control current with the set current reference value, and output a valid forced drive signal when the control current is greater than the current reference value. The forced drive signal is used to force the logic module to output a valid duty cycle signal to the drive module to force the power tube in the drive module to turn on.

[0008] Optionally, the fast transient response circuit also includes a DC operating point providing module, the input end of the DC operating point providing module is connected to the positive power supply of the DC switching power supply, the control end of the DC operating point providing module is connected to the output end of the output dynamic detection module, the output end of the DC operating point providing module is grounded, and the DC operating point providing module is used to provide a DC operating point for the input end of the comparator to ensure that the comparator outputs an invalid forced drive signal when the output end voltage is in a steady state.

[0009] Optionally, the output dynamic detection module includes a capacitor, one end of the capacitor is connected to the output end of the driving module, and the other end of the capacitor is connected to the input end of the comparator.

[0010] Optionally, the output dynamic detection module further includes a resistor, one end of which is connected to the control end of the DC operating point providing module, and the other end of which is respectively connected to the capacitor and the output end of the dynamic detection module.

[0011] Optionally, the comparator includes a first switching tube and a first current source, the control end of the first switching tube is connected to the output end of the output dynamic detection module, the anode of the first switching tube is connected to the positive power supply of the DC switching power supply, the cathode of the first switching tube is connected to the positive end of the first current source, and the negative end of the first current source is connected to the ground.

[0012] Optionally, the DC operating point providing module includes a second switching tube and a second current source, the control end of the second switching tube is used to connect to the output end of the output dynamic detection module, the anode of the second switching tube is connected to the positive power supply of the DC switching power supply, the cathode of the second switching tube is connected to the positive end of the second current source, and the negative end of the second current source is connected to the ground.

[0013] Optionally, the fast transient response circuit also includes: a logic NOT gate P1, a logic NOR gate P2 and an anti-multiple triggering module, the input end of the logic NOT gate P1 is connected to the output end of the comparator, the output end of the logic NOT gate P1 is connected to the first input end of the logic NOR gate P2, the second input end of the logic NOR gate P2 is connected to the output end of the anti-multiple triggering module, the input end of the anti-multiple triggering module is connected to the output end of the logic NOR gate P2, and the anti-multiple triggering module is used to control the forced drive signal to maintain the signal within a set delay time.

[0014] Optionally, the anti-multiple triggering module includes four D flip-flops and a logic NOT gate, wherein the D input terminal of the first D flip-flop is used to connect to the positive power supply, the CK input terminal of the first D flip-flop is used to connect to the output terminal of the comparator, and the QR output terminal of the first D flip-flop is used to connect to the second input terminal of the logic NOR gate P2; the D input terminal of the second D flip-flop is connected to the QN output terminal of the second D flip-flop, the CK input terminal of the second D flip-flop is used to receive a clock signal, the R input terminal of the second D flip-flop is connected to the QR output terminal of the first D flip-flop, and the QR output terminal of the second D flip-flop is connected to the CK input terminal of the third D flip-flop;

[0015] The D input of the third D flip-flop is connected to the QN output of the third D flip-flop, the R input of the third D flip-flop is connected to the QR output of the first D flip-flop, and the QR output of the third D flip-flop is connected to the CK input of the fourth D flip-flop; the D input of the fourth D flip-flop is connected to the positive power supply, the R input of the fourth D flip-flop is connected to the QR output of the first D flip-flop, the QR output of the fourth D flip-flop is connected to the input of the logic NOT gate, and the output of the logic NOT gate is connected to the R input of the first D flip-flop.

[0016] The effect of the anti-multiple triggering module is: in order to prevent the fast transient response circuit from being triggered back and forth during the load transient jump process, thereby causing the output voltage VOUT to oscillate, a delay time is set through the anti-multiple triggering module. During this time, the fast transient response circuit is only allowed to be triggered once.

[0017] Based on the above purpose, a DC switching power supply includes:

[0018] A logic module and a driving module, wherein the logic module is connected to the driving module, and the logic module is used to output a valid duty cycle signal to the driving module to control the driving module to turn on, and the DC switching power supply also includes the fast transient response circuit.

[0019] Optionally, the logic module includes: a logic NOT gate and three logic NOR gates, wherein the input end of the logic NOT gate P3 is used to input the modulation signal, the output end of the logic NOT gate P3 is connected to the first input end of the logic NOR gate P4, the second input end of the logic NOR gate P4 is used to input the forced drive signal, the output end of the logic NOR gate P4 is connected to the first input end of the logic NOR gate P5, the second input end of the logic NOR gate P5 is connected to the output end of the logic NOR gate P6, and the output end of the logic NOR gate P5 is used to output the duty cycle signal Duty; the first input end of the logic NOR gate P6 is used to input the forced drive signal, and the second input end of the logic NOR gate P6 is used to input the clock signal.

[0020] The above technical solution has the following beneficial effects:

[0021] When the load undergoes a large sudden change in a short period of time, such as jumping from no-load to full load, the DC switching power supply and its fast transient response circuit of the present invention can detect the rapid drop of the output voltage in a short period of time by using the output dynamic detection module, and use the forced driving signal output by the comparator to force the driving module to open for a period of time to replenish energy for the output capacitor and immediately raise the output voltage, thereby ensuring that the output voltage will not drop significantly and the drop is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for use in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the accompanying drawings in the following description are only some embodiments of the present invention. For ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without paying creative labor.

[0023] Figure 1 It is a waveform diagram of the load current, the duty cycle signal Duty of the switching power supply and the output voltage VOUT when the load connected to the existing switching power supply suddenly changes from no-load to full-load;

[0024] Figure 2 is a fast transient response circuit diagram of a DC switching power supply provided in Embodiment 1 of the present invention;

[0025] Figure 3 is a fast transient response circuit diagram of a DC switching power supply provided in an example of the first embodiment of the present invention;

[0026] Figure 4 is a fast transient response circuit diagram of a DC switching power supply provided in another example of the first embodiment of the present invention;

[0027] Figure 5 is a fast transient response circuit diagram of a DC switching power supply provided in Embodiment 2 of the present invention;

[0028] Figure 6 is a specific circuit diagram of the anti-multiple triggering module provided in the second embodiment of the present invention;

[0029] Figure 7 is a timing waveform diagram of the input signal and the output signal of the anti-multiple triggering module provided in the second embodiment of the present invention;

[0030] Figure 8 is a circuit diagram of a DC switching power supply provided in Embodiment 3 of the present invention;

[0031] Fig. 9 is a specific circuit diagram of a logic module provided in an example of Embodiment 3 of the present invention;

[0032] Fig.10 is a waveform diagram of the load current, the duty cycle signal Duty of the switching power supply and the output voltage VOUT in the third embodiment of the present invention;

[0033] The symbols are explained as follows:

[0034] 1. Output dynamic detection module; 2. Comparator; 3. DC operating point providing module; 4. Logic module; 5. Drive module; 6. Load; 7. Fast transient response circuit; 8. Error amplifier; 9. Comparator; 10. Current sampling module; 11. Clock module. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In the first embodiment, Figure 2 As shown, a fast transient response circuit of a DC switching power supply is provided, comprising an output dynamic detection module 1, a comparator 2 and a DC operating point providing module 3, wherein the input end of the output dynamic detection module 1 is used to connect to the output end of a driving module 5 of the DC switching power supply, the output end of the output dynamic detection module 1 is connected to the input end of the comparator 2, and the output dynamic detection module 1 is used to obtain the output end voltage VOUT of the driving module 5, and output a control signal when it is detected that the output end voltage VOUT drops.

[0037] Figure 2In the embodiment, the input end of the comparator 2 is connected to the output end of the output dynamic detection module 1, and is used to obtain the output control signal of the output dynamic detection module 1. The output end of the comparator 2 is connected to the logic module 4 of the DC switching power supply. The comparator 2 is used to obtain the control current according to the output control signal, compare the control current with the set current reference value, and output a valid forced drive signal TR_EN when the control current is greater than the current reference value. The forced drive signal TR_EN is used to force the logic module 4 to output a valid duty cycle signal Duty to the drive module 5, and force the power tube connected in series in the drive module 5 to turn on, so that the output capacitor Cout connected to the drive module 5 is charged, so as to quickly raise the output voltage VOUT of the drive module 5.

[0038] like Figure 2 As shown, the input end of the DC operating point providing module 3 is connected to the positive power supply VDD of the DC switching power supply, the control end of the DC operating point providing module 3 is connected to the output end (also the DC operating point) in the output dynamic detection module 1, and the output end of the DC operating point providing module 3 is grounded. The DC operating point providing module 3 is used to provide a DC operating point for the input end of the comparator 2, ensuring that the comparator 2 outputs an invalid forced driving signal when the output end voltage VOUT is in a steady state, further ensuring that the purpose of not forcing the power tube to open is achieved.

[0039] In this embodiment, the control end of the power tube of the driving module 5 is used to input the duty cycle signal Duty, the anode of the power tube is connected to the positive electrode of the power supply, and the cathode of the power tube is connected to the output capacitor Cout and the load 6. Since the load state of the load 6 suddenly changes from light load or no load to full load, the above-mentioned output terminal voltage VOUT drops.

[0040] In one example, a fast transient response circuit is provided, which has the specific structures of the output dynamic detection module 1, the comparator 2 and the DC operating point providing module 3 as shown in FIG. Figure 3 As shown, the output dynamic detection module 1 includes a capacitor C1 , one end of the capacitor C1 is connected to the output end of the driving module 5 , and the other end VA of the capacitor C1 (ie, the output end of the output dynamic detection module 1 ) is connected to the input end of the comparator 2 .

[0041] In this example, the function of the output dynamic detection module 1 is to utilize the AC-passing and DC-blocking characteristics of the capacitor C1 to make the voltage at the other end VA node of the capacitor C1 simulate the rapid drop of the output voltage VOUT, so as to reasonably set the DC operating point of the comparator to enable it to work normally.

[0042] Figure 3In the embodiment, the comparator 2 includes a first switch tube PM2 (the switch tube is a P-type MOS tube) and a first current source I2. The control end of the P-type first switch tube PM2 is connected to the output end of the output dynamic detection module 1, the anode of the first switch tube PM2 is connected to the positive power supply VDD of the DC switching power supply, the cathode of the first switch tube PM2 is connected to the positive end of the first current source I2, and the negative end of the first current source I2 is connected to the ground.

[0043] In this example, the function of the comparator 2 is: the first switch tube PM2 is used as the input tube of the comparator, and the current of the first current source I2 is used as the bias current of the comparator, and its value is the current reference value. When the output voltage VOUT of the driving module 5 drops rapidly, since the voltage across the capacitor C1 cannot change suddenly, the node VA voltage will follow the output voltage VOUT and also drop rapidly. When the node VA voltage drops, the pull-up ability of the first switch tube PM2 in the comparator 2 is enhanced. After the first switch tube PM2 is turned on, a high-level forced drive signal TR_EN (i.e., an effective forced drive signal) is output. This signal will be input to the logic module 4, and the duty cycle signal Duty is forced to be high, and an effective duty cycle signal is obtained, forcing the power tube in series in the driving module 5 to open, replenishing energy for the output capacitor Cout, and preventing the output voltage VOUT of the driving module 5 from further falling, thereby achieving rapid suppression of the output voltage drop.

[0044] After the power tube is forced to be turned on, the output capacitor Cout is greatly replenished with energy, which will quickly raise the output voltage VOUT, so that the input voltage of the comparator 2 (i.e., the VA node voltage) will rise with the output voltage VOUT, and the pull-up ability of the first switch tube PM2 will be weakened. When the output voltage VOUT rises to the normal voltage, the first switch tube PM2 of the comparator 2 is turned off, and the forced drive signal TR_EN output by the comparator 2 becomes a low level, that is, the comparator 2 outputs an invalid forced drive signal, so that the fast transient response circuit does not work.

[0045] Figure 3 In the embodiment, the DC operating point providing module 3 includes a second switch tube PM1 (the switch tube is a P-type MOS tube) and a second current source I1, wherein the control end of the second switch tube PM1 is connected to the output end of the output dynamic detection module 1, the anode of the second switch tube PM1 is connected to the positive power supply VDD of the DC switching power supply, the cathode of the second switch tube PM1 is connected to the positive end of the second current source I1, and the negative end of the second current source I1 is connected to the ground.

[0046] In this example, the function of the DC operating point providing module 3 is: since the control end of the second switch tube PM1 is connected to the cathode, and the second switch tube PM1 is a P-type MOS tube, the second switch tube PM1 is always in the on state. When the output voltage VOUT of the switch tube is in a DC steady state (that is, in a non-voltage drop), a DC operating point is provided to the input end of the comparator 2 to ensure that when the DC steady state is in progress, the output end of the comparator 2 outputs a low-level signal, that is, an invalid forced drive signal.

[0047] In the comparator 2 of this example, the first switch tube PM2 is a P-type switch tube, which is turned on by triggering the switch tube to be turned on by a low level; as another implementation method, the comparator includes an N-type first switch tube, a first inverter and a first current source I2, wherein the input end of the first inverter is connected to the output end of the output dynamic detection module 1, the output end of the first inverter is connected to the control end of the N-type first switch tube, the anode of the N-type first switch tube is connected to the positive power supply VDD, the cathode of the N-type first switch tube is connected to the positive end of the first current source I2, and the negative end of the first current source I2 is connected to the ground.

[0048] The above-mentioned comparator can also realize the role of the comparator in this example, wherein the first inverter is used to invert the output end of the dynamic detection module 1 to trigger the conduction of the N-type first switch tube, which is equivalent to replacing a P-type switch tube with a combination of an inverter and an N-type switch tube to realize the signal comparison function.

[0049] Similarly, in the DC operating point providing module 3 of this example, the second switch tube PM1 is also a P-type switch tube, which is turned on by triggering the switch tube to be turned on by a low level; as another implementation method, the DC operating point providing module includes an N-type first switch tube, a second inverter and a second current source I1, wherein the control end of the N-type second switch tube is connected to the output end of the second inverter, the input end of the second inverter is connected to the output end of the output dynamic detection module 1, and the input end of the second inverter is connected to the cathode of the N-type second switch tube, the anode of the N-type second switch tube is connected to the positive power supply VDD of the DC switching power supply, the cathode of the N-type second switch tube is connected to the positive end of the second current source I1, and the negative end of the second current source I1 is connected to the ground.

[0050] The above-mentioned dynamic detection module can also realize the function of the dynamic detection module in this example, wherein the second inverter is used to invert the output end of the dynamic detection module 1 to trigger the conduction of the N-type second switch tube to provide a DC operating point.

[0051] In another example, if Figure 4As shown, a fast transient response circuit is provided, including an output dynamic detection module 1, a comparator 2 and a DC operating point providing module 3. Different from the previous example, in this example, the output dynamic detection module 1 also includes a resistor R2, one end of the resistor R2 is connected to the control end of the DC operating point providing module 3, and the other end of the resistor R2 is respectively connected to the capacitor C1 and the output end of the dynamic detection module 1.

[0052] In this example, the resistor R2 is set to make the node VA a high resistance point, which ensures that the voltage at the node VA is more sensitive to the rapid change of the output terminal VOUT.

[0053] In the second embodiment, Figure 5 As shown, a fast transient response circuit is provided. In addition to an output dynamic detection module 1, a comparator 2 and a DC operating point providing module 3, the circuit also includes a logic NOT gate P1, a logic NOR gate P2 and an anti-multiple triggering module, wherein the input end of the logic NOT gate P1 is connected to the output end of the comparator 2, the output end of the logic NOT gate P1 is connected to the first input end of the logic NOR gate P2, the second input end of the logic NOR gate P2 is connected to the output end of the anti-multiple triggering module, and the input end of the anti-multiple triggering module is connected to the output end of the logic NOR gate P2.

[0054] In this embodiment, the specific structure of the anti-multiple triggering module is as follows: Figure 6 As shown, it includes four D flip-flops and a logic NOT gate, wherein the D input terminal of the first D flip-flop is used to connect to the positive power supply VDD, the CK input terminal of the first D flip-flop is used to connect to the output terminal of the comparator 2, and the QR output terminal of the first D flip-flop is used to connect to the second input terminal of the logic NOR gate P2; the D input terminal of the second D flip-flop is connected to the QN output terminal of the second D flip-flop, the CK input terminal of the second D flip-flop is used to receive the clock signal CLK_100k, the R input terminal of the second D flip-flop is connected to the QR output terminal of the first D flip-flop, and the QR output terminal of the second D flip-flop is connected to the CK input terminal of the third D flip-flop.

[0055] The D input of the third D flip-flop is connected to the QN output of the third D flip-flop, the R input of the third D flip-flop is connected to the QR output of the first D flip-flop, and the QR output of the third D flip-flop is connected to the CK input of the fourth D flip-flop; the D input of the fourth D flip-flop is connected to the positive power supply VDD, the R input of the fourth D flip-flop is connected to the QR output of the first D flip-flop, the QR output of the fourth D flip-flop is connected to the input of the logic NOT gate, and the output of the logic NOT gate is connected to the R input of the first D flip-flop.

[0056] In this example, the function of the anti-multiple triggering module is: after detecting the falling edge of the effective forced drive signal TR_EN output by the logic NOR gate P2, the anti-multiple triggering module output control signal PTR will become a high level, and during the set delay time, the high level of the control signal PTR will force the drive signal TR_EN to be a low level to ensure that the fast transient response circuit will only be triggered once within a period of time. Specifically, the above-mentioned delay time is set by the second D flip-flop, the third D flip-flop, and the fourth flip-flop. Optionally, this delay time can be set to about 500us.

[0057] The timing waveforms of the input signal and output signal of the above-mentioned anti-multiple trigger module are as follows: Figure 7 As shown, the input signal is the forced drive signal TR_EN and the clock signal CLK_100k, and the output signal is the control signal PTR. Figure 7 It can be seen that when the falling edge of the forced driving signal TR_EN arrives, the control signal PTR will be set to a high level within a set period of time.

[0058] In this embodiment, the specific structures of the output dynamic detection module 1, the comparator 2 and the DC operating point providing module 3 refer to the relevant records in the first embodiment, which will not be described in detail in this embodiment.

[0059] Combine the following Figure 5 , the working process of the fast transient response circuit in this embodiment is described:

[0060] When the output voltage VOUT detected by the output dynamic detection module 1 drops, the comparator 2 outputs a valid control signal TR_EN1 (a high-level signal). The signal passes through the logic NOT gate P1 and the logic NOR gate P2 to output a valid forced drive signal TR_EN (a high-level signal). When the signal TR_EN is at a high level, the duty cycle signal Duty is forced to output a high level, quickly replenishing the output capacitor Cout, and the output terminal VOUT rises rapidly.

[0061] When the output voltage VOUT detected by the output dynamic detection module 1 returns to a steady state (i.e., the voltage value returns to within the normal voltage range), the comparator 2 outputs an invalid control signal TR_EN1 (a low-level signal), which passes through the logic NOT gate P1 and the logic NOR gate P2, and outputs an invalid forced drive signal TR_EN (a low-level signal). When the signal TR_EN is at a low level, the loop control is restored, i.e., when the signal TR_EN is at a low level, the fast transient response circuit no longer controls the duty cycle signal Duty of the logic module 4. The duty cycle signal Duty output by the logic module 4 is determined by the clock signal CLK_100k and the modulation signal PWM inside the DC switching power supply, i.e., the rising edge of the clock signal CLK_100k will cause the duty cycle signal Duty to output a high level, and the high level of the modulation signal PWM will cause the duty cycle signal Duty to output a low level.

[0062] In the third embodiment, Figure 8 As shown, a DC switching power supply is provided, including the fast transient response circuit 7 in the above-mentioned embodiment 1 or embodiment 2, and also including a logic module 4, a driving module 5, an error amplifier 8, and a comparator 9 (the comparator is set separately, not Figures 2 to 5 ), a current sampling module 10 and a clock module 11, wherein a first input end of the error amplifier 8 is connected to an output end of the driving module 5, a second input end of the error amplifier 8 is used to input a reference voltage Vref, an output end of the error amplifier 8 is connected to a first input end of the comparator 9, a second input end of the comparator 9 is connected to an output end of the current sampling module 10, and an input end of the current sampling module 10 is connected to the driving module 5.

[0063] like Figure 8 As shown, the output end of the comparator 9 is connected to the first input end of the logic module 4 , the second input end of the logic module 4 is connected to the output end of the clock module 11 , and the third input end of the logic module 4 is connected to the output end of the fast transient response circuit 7 .

[0064] In this embodiment, the working principle of the DC switching power supply is:

[0065] The error amplifier 8 receives the output voltage VOUT of the driving module 5 through the first input terminal, compares the output voltage VOUT with the reference voltage Vref, performs error amplification, outputs an error signal, and outputs the error signal to the first input terminal of the comparator 9. The comparator 9 is used to obtain the output current value CS of the driving module 5 through the current sampling module 10, compares the current value CS with the error signal, and outputs the modulation signal PWM to the first input terminal of the logic module 4; the second input terminal of the logic module 4 is used to receive the clock signal CLK (i.e., the clock signal CLK_100k in Example 2) from the clock module 11, and the third input terminal of the logic module 4 is used to receive the forced drive signal TR_EN output by the fast transient response circuit 7, and output the duty cycle signal Duty according to the modulation signal PWM, the clock signal CLK and the forced drive signal TR_EN.

[0066] In one example, a specific structure of a logic module is provided, such as Fig. 9 As shown, the logic module includes a logic NOT gate and three logic NOR gates, wherein the input end of the logic NOT gate P3 is used to input the modulation signal PWM, the output end of the logic NOT gate P3 is connected to the first input end of the logic NOR gate P4, the second input end of the logic NOR gate P4 is used to input the forced drive signal TR_EN, the output end of the logic NOR gate P4 is connected to the first input end of the logic NOR gate P5, the second input end of the logic NOR gate P5 is connected to the output end of the logic NOR gate P6, and the output end of the logic NOR gate P5 is used to output the duty cycle signal Duty.

[0067] Fig. 9 In the embodiment, the first input terminal of the logic NOR gate P6 is used to input the forced driving signal TR_EN, the second input terminal of the logic NOR gate P6 is used to input the clock signal CLK, and the output terminal of the logic NOR gate P6 is connected to the second input terminal of the logic NOR gate P5.

[0068] The working principle of the above logic module is:

[0069] When the logic module receives a valid forced drive signal TR_EN (a high-level signal), the forced logic module outputs a high-level duty cycle signal Duty; when the logic module receives an invalid forced drive signal TR_EN (a low-level signal), the duty cycle signal Duty output by the logic module 4 is determined by the clock signal CLK and the modulation signal PWM inside the DC switching power supply, that is, the rising edge of the clock signal CLK will cause the duty cycle signal Duty to output a high level, and the high level of the modulation signal PWM will cause the duty cycle signal Duty to output a low level.

[0070] In order to verify the effect of the fast transient response circuit in the DC switching power supply, the DC switching power supply is simulated online. Taking the output capacitor Cout as 14uF as an example, the piezoelectric effect is not considered. When the load undergoes a transient jump, the output voltage and the waveforms of each node in the loop are as follows: Fig.10 As shown in Figure 1, when the load current changes from 0.5mA to 1A within 1us, the output voltage VOUT drops by about 56mV ( Fig.10 The difference between the vertical coordinates of the nodes A1 and B1 in the middle greatly reduces the drop of VOUT during transient jumps.

[0071] The embodiments described above are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. Such modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included in the protection scope of the present invention.

Claims

1. A fast transient response circuit of a DC switching power supply, characterized in that: include: It includes an output dynamic detection module and a comparator, wherein the input end of the output dynamic detection module is used to connect to the output end of the driving module of the DC switching power supply, the output end of the output dynamic detection module is connected to the input end of the comparator, and the output dynamic detection module is used to obtain the output end voltage of the driving module, and output a control signal when detecting that the output end voltage drops; The input end of the comparator is connected to the output end of the output dynamic detection module, and is used to obtain the output control signal of the output dynamic detection module. The output end of the comparator is connected to the logic module of the DC switching power supply. The comparator is used to obtain the control current according to the output control signal, compare the control current with the set current reference value, and output a valid forced drive signal when the control current is greater than the current reference value. The forced drive signal is used to force the logic module to output a valid duty cycle signal to the drive module to force the power tube in the drive module to turn on.

2. The fast transient response circuit of a DC switching power supply according to claim 1, characterized in that: The fast transient response circuit also includes a DC operating point providing module, the input end of the DC operating point providing module is connected to the positive power supply of the DC switching power supply, the control end of the DC operating point providing module is connected to the output end of the output dynamic detection module, the output end of the DC operating point providing module is grounded, and the DC operating point providing module is used to provide a DC operating point for the input end of the comparator to ensure that the comparator outputs an invalid forced driving signal when the output end voltage is in a steady state.

3. The fast transient response circuit of a DC switching power supply as claimed in claim 2, characterized in that: The output dynamic detection module includes a capacitor, one end of the capacitor is connected to the output end of the driving module, and the other end of the capacitor is connected to the input end of the comparator.

4. The fast transient response circuit of a DC switching power supply as claimed in claim 3, characterized in that: The output dynamic detection module also includes a resistor, one end of which is connected to the control end of the DC operating point providing module, and the other end of which is respectively connected to the capacitor and the output end of the dynamic detection module.

5. The fast transient response circuit of a DC switching power supply as claimed in claim 1, characterized in that: The comparator includes a first switch tube and a first current source, the control end of the first switch tube is connected to the output end of the output dynamic detection module, the anode of the first switch tube is connected to the positive power supply of the DC switching power supply, the cathode of the first switch tube is connected to the positive end of the first current source, and the negative end of the first current source is connected to the ground.

6. The fast transient response circuit of a DC switching power supply as claimed in claim 2, characterized in that: The DC operating point providing module includes a second switch tube and a second current source, the control end of the second switch tube is used to connect to the output end of the output dynamic detection module, the anode of the second switch tube is connected to the positive power supply of the DC switching power supply, the cathode of the second switch tube is connected to the positive end of the second current source, and the negative end of the second current source is connected to the ground.

7. The fast transient response circuit of a DC switching power supply according to claim 1, characterized in that: The fast transient response circuit also includes: a logic NOT gate P1, a logic NOR gate P2 and an anti-multiple triggering module, wherein the input end of the logic NOT gate P1 is connected to the output end of the comparator, the output end of the logic NOT gate P1 is connected to the first input end of the logic NOR gate P2, the second input end of the logic NOR gate P2 is connected to the output end of the anti-multiple triggering module, the input end of the anti-multiple triggering module is connected to the output end of the logic NOR gate P2, and the anti-multiple triggering module is used to control the forced drive signal to maintain the signal within the set delay time.

8. The fast transient response circuit of a DC switching power supply as claimed in claim 7, characterized in that: The anti-multiple triggering module includes four D flip-flops and a logic NOT gate, wherein the D input terminal of the first D flip-flop is used to connect to the positive power supply, the CK input terminal of the first D flip-flop is used to connect to the output terminal of the comparator, and the QR output terminal of the first D flip-flop is used to connect to the second input terminal of the logic NOR gate P2; the D input terminal of the second D flip-flop is connected to the QN output terminal of the second D flip-flop, the CK input terminal of the second D flip-flop is used to receive a clock signal, the R input terminal of the second D flip-flop is connected to the QR output terminal of the first D flip-flop, and the QR output terminal of the second D flip-flop is connected to the CK input terminal of the third D flip-flop; The D input of the third D flip-flop is connected to the QN output of the third D flip-flop, the R input of the third D flip-flop is connected to the QR output of the first D flip-flop, and the QR output of the third D flip-flop is connected to the CK input of the fourth D flip-flop; the D input of the fourth D flip-flop is connected to the positive power supply, the R input of the fourth D flip-flop is connected to the QR output of the first D flip-flop, the QR output of the fourth D flip-flop is connected to the input of the logic NOT gate, and the output of the logic NOT gate is connected to the R input of the first D flip-flop.

9. A DC switching power supply, comprising a logic module and a driving module, wherein the logic module is connected to the driving module, and the logic module is used to output a valid duty cycle signal to the driving module to control the driving module to turn on, characterized in that: The DC switching power supply further comprises a fast transient response circuit as claimed in any one of claims 1 to 8.

10. The DC switching power supply according to claim 9, characterized in that: The logic module includes: a logic NOT gate and three logic NOR gates, wherein the input end of the logic NOT gate P3 is used to input the modulation signal, the output end of the logic NOT gate P3 is connected to the first input end of the logic NOR gate P4, the second input end of the logic NOR gate P4 is used to input the forced drive signal, the output end of the logic NOR gate P4 is connected to the first input end of the logic NOR gate P5, the second input end of the logic NOR gate P5 is connected to the output end of the logic NOR gate P6, and the output end of the logic NOR gate P5 is used to output the duty cycle signal Duty; the first input end of the logic NOR gate P6 is used to input the forced drive signal, and the second input end of the logic NOR gate P6 is used to input the clock signal.

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