CN216086483U - BOOST type switch power supply voltage regulator - Google Patents
BOOST type switch power supply voltage regulator Download PDFInfo
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- CN216086483U CN216086483U CN202121684347.4U CN202121684347U CN216086483U CN 216086483 U CN216086483 U CN 216086483U CN 202121684347 U CN202121684347 U CN 202121684347U CN 216086483 U CN216086483 U CN 216086483U
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Abstract
The utility model discloses a BOOST type switching power supply voltage regulator, which comprises: the circuit comprises an input end IN, an output end OUT, a control end CT, an inductor L1, a switch tube NM1, a first P-type channel MOS field effect tube PM1, a second P-type channel MOS field effect tube PM2, a capacitor C1, a resistance voltage division network, an error amplifier EA and a voltage comparator COMP. The BOOST type switching power supply voltage regulator provided by the utility model can solve the problem of output voltage value limitation existing in the traditional BOOST type switching power supply voltage regulator structure, and improves the stability of a circuit.
Description
Technical Field
The utility model belongs to the technical field of electronic circuits, relates to a switching power supply circuit, and particularly relates to a BOOST type switching power supply voltage regulator.
Background
A switching mode power supply voltage regulator is a type of topology commonly used in power supply design that has the capability to generate a regulated, regulated output voltage. The structure of the voltage divider determines that the output voltage can be adjusted artificially, and the voltage divider is widely used in a power supply functional module because a voltage divider sampling network, an error amplifier and a pulse width modulator form a stable loop. The performance of a switched-mode power supply voltage regulator has a large impact on the overall circuit.
The switching power supply voltage regulator typically includes a BUCK switching power supply voltage regulator and a BOOST switching power supply voltage regulator. The BUCK type switching power supply voltage regulator is also called as a step-down regulator, and the structure of the BUCK type switching power supply voltage regulator determines that the regulator can normally and stably work when the output voltage is lower than the input voltage; the BOOST type switching power supply voltage regulator is also called a BOOST regulator, and the BOOST regulator can normally and stably work only when the output voltage is determined to be higher than the input voltage by the structure of the BOOST regulator.
Taking a conventional BUCK-type switching power supply voltage regulator circuit as an example: when the switch tube is switched on, the input end of the circuit charges the inductor, and simultaneously provides current for the load at the output end. According to the circuit structure schematic diagram of the BUCK type switching power supply voltage regulator, the approximate equation when the switching tube is turned on and off can be briefly listed by neglecting the diode voltage drop:
ton ═ T · D, toff ═ T · (1-D); wherein T is the switching time period of the switching tube, and D is the corresponding duty ratio. Because when the switching tube switching condition changes, the current in the inductance can not change suddenly, so solve the equation and can obtain: vOUT＝VIND, it can be seen that the output voltage that can be obtained by adjusting the duty cycle of the switching tube in this configuration is equal to or less than the input voltage, and the stabilization of the output voltage is ensured by the feedback loop formed by the voltage divider network and the error amplifier connected to the output terminal.
Taking a traditional BOOST type switching power supply voltage circuit as an example: when the switch tube is switched on, the input end of the circuit charges the inductor, and when the switch tube is switched off, the current of the inductor cannot change suddenly, so that the polarity of the inductor changes and supplies current to the load together with the input end of the circuit. According to the structural schematic diagram of the BOOST type switching power supply voltage circuit, the conduction voltage drop of a diode is ignored, and the conduction and the turn-off of a switching tube are briefly listedApproximate equation:
ton ═ T · D, toff ═ T · (1-D); wherein T is the switching time period of the switching tube, and D is the corresponding duty ratio. Because when the switching tube switching condition changes, the current in the inductance can not change suddenly, so solve the equation and can obtain:
it can be seen that the output voltage obtained by adjusting the duty ratio of the switching tube under the structure is greater than or equal to the input voltage, and meanwhile, the stability of the output voltage is ensured by a feedback loop formed by a voltage division network, an error amplifier and the like connected with the input end.
In practical applications, it is the most basic requirement of a switching regulator to be able to correctly output an adjustable and stable output voltage value, and the key factor of whether a power supply circuit using the structure is feasible or not. However, since the circuit structure of the BUCK-type switching power supply voltage regulator and the circuit structure of the BOOST-type switching power supply voltage regulator determine that the output voltage has an adjustable voltage range, this is undoubtedly a great limitation in practical application, and will have a great influence on the subsequent structural design.
In view of the above, there is a need to design a new switching mode power supply voltage regulator to overcome at least some of the above-mentioned disadvantages of the existing switching mode power supply voltage regulators.
SUMMERY OF THE UTILITY MODEL
The utility model provides a BOOST type switching power supply voltage regulator, which can solve the problem of limitation of an output voltage value existing in the traditional BOOST type switching power supply voltage regulator structure and improve the stability of a circuit.
In order to solve the technical problem, according to one aspect of the present invention, the following technical solutions are adopted:
a BOOST-type switching power supply voltage regulator, the voltage regulator comprising:
an input terminal IN for providing an input voltage;
an output terminal OUT for providing an output voltage;
an inductor L1, the dotted terminal of which is connected to the input terminal IN, for providing current to the load together with the voltage at the input terminal IN after the switching tube NM1 is turned off;
the switch tube NM1 is connected between the different name end of the inductor L1 and the ground;
the substrate and the drain of the first P-type channel MOS field effect transistor PM1 are connected together to replace a diode, and the voltage loss caused by the conduction voltage drop of the diode is reduced by the synchronous rectification technology;
the substrate of the second P-type channel MOS field effect transistor PM2 is connected with the source stage together and is used for playing the role of an equivalent resistor to reduce voltage when the voltage of the output end needs to be smaller than that of the input end;
the first P-type channel MOS field effect transistor PM1 and the second P-type channel MOS field effect transistor PM2 are connected between the synonym terminal of the inductor L1 and the output terminal OUT in series;
a capacitor C1 connected between the output terminal OUT and ground for providing current to the load when the switching tube NM1 is turned on;
the resistor voltage-dividing network is connected between the output end OUT and the ground;
an error amplifier EA having as input an output of the resistance voltage divider network and a reference voltage VREF 1;
the pulse width modulator PWM takes the output of the error amplifier EA and a sawtooth wave Vt with the period T as input, the output of the pulse width modulator PWM is connected to the grid electrode of the switching tube NM1 and is used for adjusting the duty ratio of the output voltage of the pulse width modulator according to a reference voltage VREF1, so that the proportion of the on-time and the off-time in the cycle period of the switching tube NM1 is adjusted, and the output current and the output voltage are finally adjusted;
the voltage comparator COMP takes an input end IN and an output end OUT as input ends, and the output end of the voltage comparator COMP is connected to the grid electrode of the second P-type channel MOS field effect transistor PM 2;
and the control terminal CT is used for controlling the conduction of the first P-type channel MOS field effect transistor PM1, so that the first P-type channel MOS field effect transistor PM1 can respectively turn off and turn on the first P-type channel MOS field effect transistor PM1 when the switching transistor is turned on and off.
As an implementation mode of the utility model, the resistance voltage division network comprises a first resistor R1 and a second resistor R2 which are connected in series.
In an embodiment of the utility model, the switching transistor NM1 is an N-channel MOS field effect transistor.
As an embodiment of the present invention, when the switching transistor NM1 is turned on, the control terminal CT outputs a high level to turn off the first P-channel MOS fet PM 1; when the switching tube NM1 is turned off, the control terminal CT outputs a low level to turn on the first P-type channel MOS fet PM 1; thereby reducing losses due to the conduction voltage drop of diode D1.
As an embodiment of the present invention, the voltage reduction operation at the time when the output voltage value of the output terminal OUT is lower than the input voltage value of the input terminal IN is performed by using the voltage comparator COMP having the input voltage of the input terminal IN and the output voltage of the output terminal OUT as inputs and the second P-channel MOS fet PM2 whose gate is controlled by the output of the voltage comparator COMP.
As an embodiment of the present invention, if the output voltage value of the output terminal OUT needs to be increased or decreased within the adjustment range larger than the input voltage value of the input terminal IN, a corresponding reference voltage VREF1 is set according to the required output voltage value and the resistor divider network;
the error amplifier EA and the pulse width modulator PWM adjust the duty ratio of square wave output of the pulse width modulator PWM according to the partial pressure sampling value and the reference voltage value of the current output voltage, so that the conduction time of a switching tube is adjusted; the charging time of the inductor L1 is changed, so that during the off period of the switching tube, the electric energy which the inductor L1 can provide to the load is changed correspondingly, resulting in a corresponding change of the output voltage at the output terminal OUT;
after the output voltage of the output end OUT is divided by the resistor voltage dividing network, the divided voltage value is equal to the reference voltage value VREF1, the feedback loop is stable, and the output voltage of the output end OUT is further kept stable.
As an embodiment of the present invention, if the output voltage value of the output terminal OUT needs to be increased or decreased within the adjustment range smaller than the input voltage value of the input terminal IN, a corresponding reference voltage VREF1 is set according to the required output voltage value and the resistor divider network;
the error amplifier EA and the pulse width modulator PWM can reduce the duty ratio of square wave output of the pulse width modulator PWM according to the voltage division sampling value and the reference voltage value of the current larger output voltage, so that the conduction time of a switching tube is shortened; the charging time of the inductor L1 is further shortened, so that during the turn-off period of the switching tube, the electric energy which can be provided by the inductor L1 for the load is correspondingly reduced, and the output voltage of the output end OUT is reduced;
when the output voltage of the output end OUT is reduced to be equal to the input voltage of the input end IN, and the voltage comparator COMP taking the input voltage of the input end IN and the output voltage of the output end IN as input detects the condition, outputting a high level to the gate of the second P-channel MOS field effect transistor PM2 to pinch off the second P-channel MOS field effect transistor PM 2;
at this time, although the switching tube is kept off, the input end IN is conducted to the source of the PM2 through the PN junction formed by the source and the substrate of the first P-type channel MOS field effect transistor PM1, but cannot be conducted to the output end OUT through the NP junction formed by the substrate connected with the source and the drain, and the only method through the PM2 is through the channel transmission of the PM 2;
after the second P-channel MOS fet PM2 is pinched off, the output voltage at the output terminal OUT will be lowered due to the path from the load to the ground, and when the divided sampling value of the output voltage at the output terminal OUT is smaller than the reference voltage value, the error amplifier EA and the pulse width modulator PWM will output a square wave to the gate of the switching tube. Then the inductor L1 starts to perform the charging and discharging action again, IN the period of the first switching tube recovering to turn on and off again, when the switching tube is turned off, the voltage value of the synonym terminal of the inductor L1 is equal to the voltage value of the inductor L1 plus the voltage value of the input terminal IN, and the voltage value reaches the source of the second P-type channel MOS field effect transistor PM2 through the turned-on first P-type channel MOS field effect transistor PM1, so that the second P-type channel MOS field effect transistor PM2 works IN the saturation region, which is equivalent to a resistor to complete the voltage reduction;
the output voltage of the output end OUT changes correspondingly, and the continuous adjustment of the feedback loop is caused; finally, when the divided voltage sampling value of the output voltage at the output end OUT is equal to the reference voltage value, the feedback loop is stable, and a stable output voltage value OUT with a voltage value lower than the input voltage value of the input end IN is further obtained.
The utility model has the beneficial effects that: the BOOST type switching power supply voltage regulator provided by the utility model can solve the limitation of the output voltage value existing in the traditional BOOST type switching power supply voltage regulator structure.
When the voltage of the output end OUT is required to be smaller than the voltage of the input end IN, the voltage value of VREF1 is firstly set according to the required voltage value of the output end, the duty ratio D of the output square wave of the pulse width modulator PWM is changed into 0 through a feedback loop, the output end OUT is equivalently directly communicated with the input end IN, and therefore the voltage of the output end OUT is equal to the voltage of the input end IN. Then the voltage comparator COMP detects that the voltage at the output terminal is equal to the voltage at the input terminal, and outputs a high level to the gate of PM2, so that PM2 operates IN the saturation region and is equivalent to a resistor, and the voltage reduction process from the input terminal IN to the output terminal OUT is completed. At this time, a new feedback relationship is formed due to the participation of the PM2, and the output voltage of the output terminal OUT having a voltage value lower than the input voltage of the input terminal IN can be stabilized by the feedback loop.
Drawings
FIG. 1 is a schematic diagram of a conventional BUCK-type switching power supply voltage regulator.
Fig. 2 is a schematic diagram of a conventional BOOST-type switching power supply voltage regulator.
Fig. 3 is a schematic diagram of a topology of an exemplary switching power supply voltage regulator according to the present invention.
Detailed Description
Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.
For a further understanding of the utility model, reference will now be made to the preferred embodiments of the utility model by way of example, and it is to be understood that the description is intended to further illustrate features and advantages of the utility model, and not to limit the scope of the claims.
The description in this section is for several exemplary embodiments only, and the present invention is not limited only to the scope of the embodiments described. It is within the scope of the present disclosure and protection that the same or similar prior art means and some features of the embodiments may be interchanged.
It should be noted that the relational terms such as first and second, and the like in the present invention are used solely to distinguish one entity or action from another entity or action without necessarily representing any actual relationship or order between the entities or actions. The drawings provided herein are for illustrative purposes only to show the basic concepts of the present invention, and not for the purpose of limiting the utility model, but to show the components related to the present invention in terms of the number, shape and size of the components in actual implementation.
The steps in the embodiments in the specification are only expressed for convenience of description, and the implementation manner of the present application is not limited by the order of implementation of the steps.
"coupled" in this specification includes both direct and indirect connections, such as through some active device, passive device, or electrically conductive medium; but also may include connections through other active or passive devices, such as through switches, follower circuits, etc., that are known to those skilled in the art for achieving the same or similar functional objectives.
FIG. 2 is a schematic diagram of a conventional BOOST-type switching power supply voltage regulator circuit; referring to fig. 2, assuming that the output voltage and the output current are already established at this time, when the switching tube NM1 is turned on, the input terminal IN is connected to ground through the inductor L1 and the switching tube NM1, that is, the input terminal IN charges the inductor L1 for a duration TD, T is a period of the sawtooth wave Vt, D is a duty ratio of the pulse width modulator output square wave, and during this period, the polarity of the dotted terminal of the inductor is positive and the polarity of the dotted terminal of the inductor is negative; at the moment when the switching tube NM1 is turned off, since the current of the inductor cannot change abruptly and the output voltage of the output terminal OUT is greater than the input voltage of the input terminal IN, at the moment when the switching tube is turned off, the inductor current remains unchanged but the polarity changes, that is, the polarity of the dotted terminal is negative and the polarity of the dotted terminal is positive. The inductor then acts as a power supply IN the same direction as the input OUT and supplies power to the output OUT together with the input IN, so that the output voltage at the output OUT is higher than the input IN.
The circuit structure of the conventional BOOST-type switching power supply voltage regulator has the function of adjusting the output voltage of the output end OUT through a feedback loop, which is also the basic function of the switching power supply voltage regulator.
Specifically, if an output voltage smaller than the output voltage value of the current output terminal OUT is required to be obtained within the adjustment range, the corresponding reference voltage VREF1 may be set according to the required output voltage value and the resistance voltage divider network, and the error amplifier EA and the pulse width modulator PWM may reduce the duty ratio of the output voltage of the pulse width modulator PWM according to the divided sampling value and the reference voltage value of the current larger output voltage, so as to shorten the on-time of the switching tube. And further, the charging time of the inductor L1 is shortened, so that during the off period of the switching tube, the electric energy which can be provided by the inductor L1 for the load is correspondingly reduced, which results in the output voltage of the output end OUT being reduced, and when the divided voltage value of the output voltage of the output end OUT is equal to the reference voltage VREF1 after the voltage division of the output voltage of the output end OUT through the resistor voltage division network, the feedback loop is stable, and further, the output voltage of the output end OUT is also kept stable.
Specifically, if an output voltage larger than the output voltage value of the current output terminal OUT is required to be obtained within the adjustment range, the corresponding reference voltage VREF1 may be set according to the required output voltage value and the resistance voltage divider network, and the error amplifier EA and the pulse width modulator PWM may increase the duty ratio of the square wave output of the pulse width modulator PWM according to the divided voltage sampling value and the reference voltage value of the current smaller output voltage, so that the on-time of the switching tube is prolonged. And further, the charging time of the inductor L1 is prolonged, so that during the off period of the switching tube, the electric energy which can be provided by the inductor L1 to the load is correspondingly increased, and the output voltage of the output end OUT is increased, and after the output voltage of the output end OUT is divided by the resistor voltage dividing network, the divided voltage value is equal to the reference voltage VREF1, the feedback loop is stable, and further, the output voltage of the output end OUT is also kept stable.
Specifically, if the output voltage value of the output terminal OUT is required to be smaller than the input voltage value of the input terminal IN, the corresponding reference voltage VREF1 is set according to the required output voltage value and the resistance voltage dividing network according to the operation method, and the error amplifier and the pulse width modulator reduce the duty ratio of the square wave output of the pulse width modulator PWM according to the divided voltage sampling value and the reference voltage value of the current larger output voltage, so that the on-time of the switching tube is shortened. The charging time of the inductor L1 is further shortened, so that the electric energy which can be provided by the inductor L1 to the load is also reduced correspondingly during the turn-off period of the switch tube, resulting in the reduction of the output voltage at the output terminal OUT. However, when the duty ratio of the PWM square wave output reaches 0, which corresponds to the switching tube being turned off, the input terminal IN is directly connected to the output terminal OUT via the inductor L1 and the diode D1, and the output voltage of the output terminal OUT is equal to the value of the input voltage of the input terminal IN minus the value of the on-state voltage of the diode D1, the switching regulator loses its regulation capability.
When the required output voltage of the output terminal OUT is lower than the input voltage, the conventional BOOST-type switching power supply voltage regulator fails, which indicates that the conventional BOOST-type switching power supply voltage regulator has the limitation of the output voltage, which undoubtedly affects the design of the subsequent structure in practical application, and thus has a significant impact.
Fig. 3 is a schematic diagram of a BOOST topology structure according to an embodiment of the present invention; referring to fig. 3, the present invention discloses a BOOST-type switching power supply voltage regulator, which includes: the circuit comprises an input end IN, an output end OUT, a control end CT, an inductor L1, a switch tube NM1, a first P-type channel MOS field effect tube PM1, a second P-type channel MOS field effect tube PM2, a capacitor C1, a resistance voltage division network, an error amplifier EA and a voltage comparator COMP.
The input end IN is used for providing an input voltage; the output terminal OUT is used to provide an output voltage. The dotted terminal of the inductor L1 is connected to the input terminal IN, and is used to supply current to the load together with the voltage at the input terminal IN after the switching tube NM1 is turned off.
The switch tube NM1 is connected between the different name end of the inductor L1 and the ground, is used as a switch tube in a circuit, and adjusts the output voltage of the output end by adjusting the proportion of the on-time and the off-time in a single period of NM 1. In one embodiment, the switch NM1 is an N-channel MOS fet.
The substrate and the drain of the first P-channel MOS field effect transistor PM1 are connected together to replace a diode, and the voltage loss caused by the conduction voltage drop of the diode is reduced through a synchronous rectification technology. The substrate of the second P-type channel MOS field effect transistor PM2 is connected with the source stage together, so as to play the role of an equivalent resistor for reducing voltage when the voltage of the output end needs to be smaller than that of the input end; the first P-type channel MOS field effect transistor PM1 and the second P-type channel MOS field effect transistor PM2 are connected between the synonym terminal of the inductor L1 and the output terminal OUT in a series mode.
The capacitor C1 is connected between the output terminal OUT and ground, and is used for supplying current to the load when the switching tube NM1 is turned on. The resistance voltage division network is connected between the output end OUT and the ground; in one embodiment, the resistor divider network comprises a first resistor R1 and a second resistor R2 connected in series.
The error amplifier EA takes as input the output of the resistor divider network and the reference voltage VREF 1. The output of the pulse width modulator PWM takes the output of the error amplifier EA and the sawtooth wave Vt with the period T as input, and the output of the pulse width modulator PWM is connected to the gate of the switching tube NM1, and is used for adjusting the duty ratio of the output voltage of the pulse width modulator according to the reference voltage VREF1, so as to adjust the proportion of the on-time and the off-time in the cycle period of the switching tube NM1, and finally adjust the output current and the output voltage.
The voltage comparator COMP takes an input end IN and an output end OUT as input ends, and the output end of the voltage comparator COMP is connected to the grid electrode of the second P-type channel MOS field effect transistor PM 2.
The control terminal CT is used to control the conduction of the first P-channel MOS fet PM1, so that the first P-channel MOS fet PM1 can turn off and turn on the first P-channel MOS fet PM1 when the switching transistor is turned on and off, respectively.
The utility model also discloses a control method of the BOOST type switching power supply voltage regulator, which comprises the following steps:
when the switching tube NM1 is turned on, the control terminal CT outputs a high level to turn off the first P-channel MOS fet PM 1; when the switching tube NM1 is turned off, the control terminal CT outputs a low level to turn on the first P-type channel MOS fet PM 1; thereby reducing the loss caused by the conduction voltage drop of the diode D1;
the voltage reduction operation at the moment when the output voltage value of the output end OUT is lower than the input voltage value of the input end IN is completed by adopting a voltage comparator COMP taking the input voltage of the input end IN and the output voltage of the output end OUT as input and a second P-type channel MOS field effect transistor PM2 controlled by the output of the voltage comparator COMP.
Different from the traditional BOOST type switching power supply voltage regulator structure, the structure of the utility model adopts the synchronous rectification technology, and the original diode D1 is replaced by a P-type channel MOS field effect transistor PM1 of a control gate of a control end CT. When the switching tube NM1 is turned on, the control terminal CT outputs a high level to turn off the PM 1; when the switch NM1 is turned off, the control terminal CT outputs a low level to turn on the PM1, which is aimed at reducing the loss caused by the voltage drop of the diode D1. IN addition, the voltage reduction operation at the time when the output voltage value of the output terminal OUT is lower than the input voltage value of the input terminal IN is performed by using the voltage comparator COMP having the input voltage of the input terminal IN and the output voltage of the output terminal OUT as inputs and the P-channel MOS fet PM2 having the output control gate of the voltage comparator COMP.
IN an embodiment, if the output voltage value of the output terminal OUT needs to be increased or decreased within the adjustment range larger than the input voltage value of the input terminal IN, the corresponding reference voltage VREF1 is set according to the required output voltage value and the resistor voltage dividing network, and the error amplifier EA and the pulse width modulator PWM adjust the duty ratio of the square wave output of the pulse width modulator PWM according to the divided sampling value and the reference voltage value of the current output voltage, so that the on-time of the switching tube is adjusted. The charging time of the inductor L1 is thus changed, so that during the off-time of the switching tube. The inductor L1 can provide a corresponding change to the power supplied by the load, which results in a corresponding change to the output voltage at the output terminal OUT, and when the divided voltage value of the output voltage at the output terminal OUT is equal to the reference voltage value VREF1 after the divided voltage of the output voltage at the output terminal OUT is divided by the resistor voltage divider network, the feedback loop is stable, so that the output voltage at the output terminal OUT is also stable.
IN an embodiment, if the output voltage value of the output terminal OUT needs to be increased or decreased within the adjustment range smaller than the input voltage value of the input terminal IN, the corresponding reference voltage VREF1 is set according to the required output voltage value and the resistor voltage dividing network, and the error amplifier EA and the pulse width modulator PWM reduce the duty ratio of the square wave output of the pulse width modulator PWM according to the divided voltage sampling value and the reference voltage value of the current larger output voltage, so that the on-time of the switching tube is shortened. The charging time of the inductor L1 is further shortened, so that the electric energy which can be provided by the inductor L1 to the load is also reduced correspondingly during the turn-off period of the switch tube, resulting in the reduction of the output voltage at the output terminal OUT.
When the output voltage of the output terminal OUT drops to be equal to the input voltage of the input terminal IN, and the voltage comparator COMP, which takes the input voltage of the input terminal IN and the output voltage of the output terminal IN as input, detects this condition, a high level is output to the gate of the P-channel MOS fet PM2, pinching off the PM 2. At this time, although the switching tube is kept off, the input end can be conducted to the source of the PM2 through the PN junction formed by the source and the substrate of the PM1, but cannot be conducted to the output end OUT through the NP junction formed by the substrate connected with the source and the drain, and the only method for passing through the PM2 is through the channel of the PM 2.
After the PM2 is clamped off, the output voltage of the output terminal OUT will become low due to the path from the load to the ground, and when the divided sampled value of the output voltage of the output terminal OUT is smaller than the reference voltage value, the error amplifier EA and the pulse width modulator PWM will output a square wave to the gate of the switching tube. Then, the inductor L1 starts to perform the charging and discharging actions again, and IN the period when the first switching tube resumes the on and off states, when the switching tube is turned off, the voltage value at the different name end of the inductor L1 is equal to the voltage value of the inductor L1 plus the voltage value at the input end IN, and reaches the source of the PM2 through the turned-on PM1, so that the PM2 works IN the saturation region, which is equivalent to a resistor that completes the voltage reduction. In this way, the output voltage at the output terminal OUT will change accordingly, causing the feedback loop to continue to adjust. Finally, when the divided voltage sampling value of the output voltage at the output end OUT is equal to the reference voltage value, the feedback loop is stable, and a stable output voltage value OUT with a voltage value lower than the input voltage value of the input end IN is further obtained.
As described above, in the topology proposed by the present invention, when outputting low voltage, there is a P-channel MOS fet operating in the saturation region to perform the voltage reduction function, so as to obtain an output voltage with a voltage value lower than the input voltage value, and the output voltage can be adjusted by setting the reference voltage VREF 1. The problem that the output voltage of the traditional BOOST type switching power supply voltage regulator is limited in regulation range is solved.
In summary, the BOOST-type switching power supply voltage regulator provided by the utility model can solve the limitation of the output voltage value existing in the traditional BOOST-type switching power supply voltage regulator structure.
When the voltage of the output end OUT is required to be smaller than the voltage of the input end IN, the voltage value of VREF1 is firstly set according to the required voltage value of the output end, the duty ratio D of the output square wave of the pulse width modulator PWM is changed into 0 through a feedback loop, the output end OUT is equivalently directly communicated with the input end IN, and therefore the voltage of the output end OUT is equal to the voltage of the input end IN. Then the voltage comparator COMP detects that the voltage at the output terminal is equal to the voltage at the input terminal, and outputs a high level to the gate of PM2, so that PM2 operates IN the saturation region and is equivalent to a resistor, and the voltage reduction process from the input terminal IN to the output terminal OUT is completed. At this time, a new feedback relationship is formed due to the participation of the PM2, and the output voltage of the output terminal OUT having a voltage value lower than the input voltage of the input terminal IN can be stabilized by the feedback loop.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The description and applications of the utility model herein are illustrative and are not intended to limit the scope of the utility model to the embodiments described above. Effects or advantages referred to in the embodiments may not be reflected in the embodiments due to interference of various factors, and the description of the effects or advantages is not intended to limit the embodiments. Variations and modifications of the embodiments disclosed herein are possible, and alternative and equivalent various components of the embodiments will be apparent to those skilled in the art. It will be clear to those skilled in the art that the present invention may be embodied in other forms, structures, arrangements, proportions, and with other components, materials, and parts, without departing from the spirit or essential characteristics thereof. Other variations and modifications of the embodiments disclosed herein may be made without departing from the scope and spirit of the utility model.
Claims (6)
1. A BOOST-type switching power supply voltage regulator, said voltage regulator comprising:
an input terminal IN for providing an input voltage;
an output terminal OUT for providing an output voltage;
an inductor L1, the dotted terminal of which is connected to the input terminal IN, for providing current to the load together with the voltage at the input terminal IN after the switching tube NM1 is turned off;
the switch tube NM1 is connected between the different name end of the inductor L1 and the ground;
the substrate and the drain of the first P-type channel MOS field effect transistor PM1 are connected together, so that the voltage loss caused by the conduction voltage drop of the diode is reduced by the synchronous rectification technology;
the substrate of the second P-type channel MOS field effect transistor PM2 is connected with the source stage together and is used for playing the role of an equivalent resistor to reduce voltage when the voltage of the output end needs to be smaller than that of the input end; the first P-type channel MOS field effect transistor PM1 and the second P-type channel MOS field effect transistor PM2 are connected between the synonym terminal of the inductor L1 and the output terminal OUT in series;
a capacitor C1 connected between the output terminal OUT and ground for providing current to the load when the switching tube NM1 is turned on;
the resistor voltage-dividing network is connected between the output end OUT and the ground;
an error amplifier EA having as input an output of the resistance voltage divider network and a reference voltage VREF 1;
the pulse width modulator PWM takes the output of the error amplifier EA and a sawtooth wave Vt with the period T as input, the output of the pulse width modulator PWM is connected to the grid electrode of the switching tube NM1 and is used for adjusting the duty ratio of the output voltage of the pulse width modulator according to a reference voltage VREF1, so that the proportion of the on-time and the off-time in the cycle period of the switching tube NM1 is adjusted, and finally the output current and the output voltage are adjusted;
the voltage comparator COMP takes an input end IN and an output end OUT as input ends, and the output end of the voltage comparator COMP is connected to the grid electrode of the second P-type channel MOS field effect transistor PM 2;
and the control terminal CT is used for controlling the conduction of the first P-channel MOS fet PM1, so that the first P-channel MOS fet PM1 can respectively turn off and turn on the first P-channel MOS fet PM1 when the switch NM1 is turned on and off.
2. A BOOST-type switching power supply voltage regulator according to claim 1, characterized in that:
the resistance voltage division network comprises a first resistor R1 and a second resistor R2 which are connected in series.
3. A BOOST-type switching power supply voltage regulator according to claim 1, characterized in that:
the switch tube NM1 is an N-type channel MOS field effect tube.
4. A BOOST-type switching power supply voltage regulator according to claim 1, characterized in that:
when the switching tube NM1 is turned on, the control terminal CT outputs a high level to turn off the first P-channel MOS fet PM 1;
when the switch NM1 is turned off, the control terminal CT outputs a low level to turn on the first P-channel mosfet PM 1.
5. A BOOST-type switching power supply voltage regulator according to claim 1, characterized in that:
the voltage reduction operation at the moment when the output voltage value of the output end OUT is lower than the input voltage value of the input end IN is completed by adopting a voltage comparator COMP taking the input voltage of the input end IN and the output voltage of the output end OUT as input and a second P-type channel MOS field effect transistor PM2 controlled by the output of the voltage comparator COMP.
6. A BOOST-type switching power supply voltage regulator according to claim 1, characterized in that:
the error amplifier EA and the pulse width modulator PWM adjust the duty ratio of square wave output of the pulse width modulator PWM according to the partial pressure sampling value and the reference voltage value of the current output voltage, so that the conduction time of a switching tube is adjusted; the charging time of the inductor L1 is changed, so that the electric energy that the inductor L1 can provide to the load is changed during the turn-off period of the switching tube, resulting in a corresponding change of the output voltage at the output terminal OUT.
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121684347.4U CN216086483U (en) | 2021-07-23 | 2021-07-23 | BOOST type switch power supply voltage regulator |
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| Application Number | Priority Date | Filing Date | Title |
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| CN202121684347.4U CN216086483U (en) | 2021-07-23 | 2021-07-23 | BOOST type switch power supply voltage regulator |
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