CN111835181A

CN111835181A - Voltage converter

Info

Publication number: CN111835181A
Application number: CN201910285612.2A
Authority: CN
Inventors: 蔡宗谚
Original assignee: Realtek Semiconductor Corp
Current assignee: Realtek Semiconductor Corp
Priority date: 2019-04-10
Filing date: 2019-04-10
Publication date: 2020-10-27

Abstract

The invention discloses a voltage converter which can operate in a synchronous mode or an asynchronous mode according to an input voltage. The voltage converter includes: a voltage detection circuit for generating a detection result according to an input voltage of an input terminal; a switch control circuit for generating a first switch control signal and a second switch control signal according to the detection result and an output voltage of an output terminal; a first switch, for intermittently conducting according to the first switch control signal in the synchronous mode and the asynchronous mode; a second switch for being intermittently turned on in the synchronous mode according to the second switch control signal and being turned off in the asynchronous mode according to the second switch control signal; and the energy storage circuit is electrically connected with the input end and the output end and used for storing and releasing energy according to the conducting state of the first switch and the second switch so as to adjust the output voltage according to the input voltage.

Description

Voltage converter

Technical Field

The present invention relates to voltage converters, and more particularly, to a voltage converter capable of operating in one of a synchronous mode and an asynchronous mode.

Background

Voltage converters are circuits that are common in the art, as shown in U.S. patent No. 4,578,630. The voltage converter generally includes a synchronous type and an asynchronous type, and the conversion efficiency of the synchronous type is generally better than that of the asynchronous type. However, although the conversion efficiency of the synchronous voltage converter is better, in some applications, the synchronous voltage converter may have other problems. Taking a synchronous buck converter of an rf device as an example, when an input voltage (e.g., 1.7V) of the synchronous buck converter is close to an output voltage (e.g., 1.1V), the input voltage interferes with an rf signal, so that phase noise of the rf signal is degraded.

In view of the foregoing, there is a need in the art for a voltage converter that allows for conversion efficiency and reduces the effects of similar input and output voltages.

Disclosure of Invention

It is an object of the present invention to provide a voltage converter to avoid the problems of the prior art.

The invention discloses a voltage converter which can operate in one of a synchronous mode and an asynchronous mode according to an input voltage. The voltage detection circuit is used for generating a detection result according to the input voltage of an input voltage end. The switch control circuit is used for generating a first switch control signal and a second switch control signal according to the detection result and the output voltage of an output voltage end. The first switch is used for being intermittently conducted in the synchronous mode and the asynchronous mode according to the first switch control signal. The second switch is used for being intermittently conducted according to the second switch control signal in the synchronous mode and is used for being not conducted according to the second switch control signal in the asynchronous mode, wherein the first switch and the second switch are not conducted at the same time. The energy storage circuit is electrically connected with the input voltage end and the output voltage end and used for storing and releasing energy according to the conducting state of the first switch and the second switch so as to adjust the output voltage according to the input voltage. Through the technical characteristics, the voltage converter can operate in the synchronous mode to consider the conversion efficiency when the input voltage is not similar to the output voltage; and when the input voltage is similar to the output voltage, the asynchronous mode can be operated to reduce the influence caused by the similar input voltage and output voltage.

The features, implementations, and technical advantages of the present invention are described in detail below with reference to the accompanying drawings.

Drawings

FIG. 1 shows an embodiment of a voltage converter according to the present invention;

FIG. 2 illustrates one embodiment of the energy storage circuit of FIG. 1;

FIG. 3 shows another embodiment of the voltage converter of the present invention; and

FIG. 4 illustrates an embodiment of the energy storage circuit of FIG. 3.

Description of the symbols

100 voltage converter

110 voltage detection circuit

120 switch control circuit

130 first switch

140 second switch

150 energy storage circuit

160 node

V_INInput voltage

V_OUTOutput voltage

V_SSTerminal of low potential

300 voltage converter

310 voltage detection circuit

320 switch control circuit

330 first switch

340 second switch

350 energy storage circuit

360 node

Detailed Description

The invention discloses a voltage converter, which can operate in one of a synchronous mode and an asynchronous mode according to an input voltage; in other words, in the synchronous mode, the voltage converter is equivalent to a synchronous voltage converter, and in the asynchronous mode, the voltage converter is equivalent to an asynchronous voltage converter. Therefore, the voltage converter can operate in the synchronous mode when the input voltage is not similar to an output voltage so as to consider conversion efficiency; and when the input voltage is similar to the output voltage, the asynchronous mode can be operated to reduce the influence caused by the similar input voltage and output voltage.

Fig. 1 shows an embodiment of a voltage converter according to the present invention. The voltage converter 100 of fig. 1 is a buck converter (bulk converter), and includes a voltage detection circuit 110, a switch control circuit 120, a first switch 130, a second switch 140, and an energy storage circuit 150; the voltage converter 100 of fig. 1 is an integrated circuit, but this is not a limitation of the present invention; in addition, the dashed lines of FIG. 1 represent alternative paths, either present or absent depending on implementation requirements.

Please refer to fig. 1. The voltage detection circuit 110 is used for detecting an input voltage V according to an input terminal_INGenerating a detection result. For example, when the voltage detection circuit 110 detects the input voltage V_INAnd the output voltage V of the output terminal described later_OUTWhen the absolute value of the difference is lower than a threshold (e.g., 0.5V), the voltage detection circuit 110 outputs the detection result, so that the switch control circuit 120 generates a first switch control signal and a second switch control signal for an asynchronous mode; when the voltage detection circuit 110 detects the input voltage V_INAnd the output voltage V_OUTWhen the absolute value of the difference is not lower than the threshold, the voltage detection circuit 110 outputs the detection result, so that the switch control circuit 120 generates the first switch control signal and the second switch control signal for a synchronous mode; when an implementation requirement requires the output voltage V_OUTWhen a specified voltage (e.g., 1.1V) is required (i.e., the output voltage V_OUTIs adjusted to be equal to or approximate to the designated voltage), the voltage detection circuit 110 sets the designated voltage according to the input voltage V_INThe input voltage V can be obtained_INAnd the output voltage V_OUTThe relationship between (e.g. the input voltage V)_INAnd the output voltage V_OUTWhether the absolute value of the difference of (d) is below the threshold); the threshold may be implementation specific. In an exemplary embodiment, the voltage detection circuit 110 is an N-bit analog-to-digital converter, N is an integer not less than one, and the N-bit analog-to-digital converter is based on the input voltage V_INAnd the output voltage V_OUTOutputting a digital value as the detection result; in another exemplary embodiment, the voltage detection circuit 110 is a voltage comparator that compares the input voltage with a reference voltage (e.g., the specified voltage plus the threshold) to output a comparison result as the detection result. Since each of the analog-to-digital converter and the voltage comparator individually may be a circuit known as self-developed, the details thereof are omitted here.

Please refer to fig. 1. The switch control circuit 120 is used for controlling the output voltage V according to the detection result of the voltage detection circuit 110 and the output voltage V of the output terminal_OUTGenerating a first switch control signal and a second switch control signal; in more detail, according to the detection result, the switch control circuit 120 can respectively control the first switch 130 and the second switch 140 to operate in one of the synchronous mode and the asynchronous mode according to the first switch control signal and the second switch control signal, and further, according to the output voltage V_OUTThe switch control circuit 120 can control the first switch 130 and the second switch 140 respectively by the first switch control signal and the second switch control signal to make the output voltage V_OUTApproaching a voltage meeting the implementation requirement. It is noted that under the control of the switch control circuit 120, the first switch 130 and the second switch 140 are not turned on simultaneously. In an implementation example, the switch control circuit 120 performs at least one of Pulse Width Modulation (PWM) and Pulse Frequency Modulation (PFM) to control the conducting states of the first switch 130 and the second switch 140. Since the switch control circuit 120 alone may be a known or self-developed circuit, details thereof are omitted herein.

Please refer to fig. 1. The first switch 130 is located at the input voltage V_INBetween the input terminal of (b) and a node 160, the second switch 140 is located between the node 160 and a low potential terminal V_SSFor example, ground. The first switch 130 is used for being intermittently turned on in the synchronous mode and the asynchronous mode according to the first switch control signal to adjust the output voltage V_OUT. The second switch 140 is used forIntermittently conducting according to the second switch control signal in a synchronous mode to adjust the output voltage; in this case, the voltage converter 100 is a synchronous voltage converter, and has a better conversion efficiency. The second switch 140 is further configured to be turned off in the asynchronous mode according to the second switch control signal, and the voltage converter 100 is an asynchronous voltage converter capable of reducing the influence of the input voltage and the output voltage. In an exemplary embodiment, each of the first switch 130 and the second switch 140 is a transistor having a gate for receiving the first/second switch control signal, wherein the second switch 140 includes a parasitic diode as a current path for current to flow through in the asynchronous mode, and thus the second switch 140 is equivalent to a diode in the asynchronous mode. In one exemplary embodiment, the first switch 130 is a first type transistor (e.g., a PMOS transistor) and the second switch is a second type transistor (e.g., an NMOS transistor). Since each of the first switch 130 and the second switch 140 individually may be a known or self-developed circuit, the details thereof are omitted herein.

Please refer to fig. 1. The energy storage circuit 150 is electrically connected to the input voltage V_INAnd the output voltage V_OUTAn output terminal for storing and releasing energy according to the conduction states of the first switch 130 and the second switch 140 to output the energy according to the input voltage V_INAdjusting the output voltage V_OUT. An embodiment of the energy storage circuit 150 is shown in fig. 2, and includes an inductor and a capacitor. The inductor is located at node 160 and the output voltage V_OUTBetween the output terminals of (1); the capacitor is arranged at the output voltage V_OUTAnd the low potential terminal V_SSIn the meantime. Since each of the inductor and the capacitor, individually, may be a known or self-developed element, the details thereof are omitted here.

Fig. 3 shows another embodiment of the voltage converter of the present invention. The voltage converter 300 of fig. 3 is a boost converter (boost converter), which includes a voltage detection circuit 310, a switch control circuit 320, a first switch 330, a second switch 340, and an energy storage circuit 350; the voltage converter 300 of fig. 3 is an integrated circuit, but this is not a limitation of the present invention; in addition, the dashed lines of FIG. 3 represent alternative paths, either present or absent depending on implementation requirements.

Please refer to fig. 3. The configuration and operation of the voltage detection circuit 310, the switch control circuit 320, the first switch 330 and the second switch 340 in fig. 3 are similar to the configuration and operation of the voltage detection circuit 110, the switch control circuit 120, the first switch 130 and the second switch 140 in fig. 1, respectively; the main difference between the embodiments of fig. 1 and 3 for the above-described circuit is the input voltage V of fig. 1_INHigher than the output voltage V_OUTAnd the input voltage V of FIG. 3_INBelow the output voltage V_OUTTherefore, the voltage detection circuit 110 of fig. 1 and the voltage detection circuit 310 of fig. 3 detect the input voltage V according to their respective voltage detection conditions_INAnd the output voltage V_OUTIn relation to each other (e.g. detecting the input voltage V)_INAnd the output voltage V_OUTWhether the absolute value of the difference between is below a threshold); in addition, compared to fig. 1, the first switch 330 of fig. 3 is located at the node 360 and a low potential terminal V_SSThe second switch 340 of FIG. 3 is located between the node 360 and the output voltage V_OUTBetween the output terminals of (a).

Please refer to fig. 3. The energy storage circuit 350 is electrically connected to the input voltage V_INAnd the output voltage V_OUTFor storing and releasing energy according to the conducting state of the first switch 330 and the second switch 340, according to the input voltage V_INAdjusting the output voltage V_OUT. An embodiment of the energy storage circuit 350 is shown in fig. 4, and includes an inductor and a capacitor. The inductor is arranged at the input voltage V_INAnd node 360; the capacitor is arranged at the output voltage V_OUTAnd the low potential terminal V_SSIn the meantime. Since each of the inductor and the capacitor, individually, may be a known or self-developed element, the details thereof are omitted here.

Since the details and variations of the embodiment of fig. 3 can be understood by those skilled in the art with reference to the disclosure of the embodiment of fig. 1, that is, the technical features of the embodiment of fig. 1 can be reasonably applied to the embodiment of fig. 3, the repeated and redundant description is omitted here.

It is to be noted that, when the implementation is possible, a person skilled in the art may selectively implement some or all of the technical features of any one of the foregoing embodiments, or selectively implement a combination of some or all of the technical features of the foregoing embodiments, thereby increasing the flexibility of implementation of the present invention.

In summary, the voltage converter of the present invention can operate in the synchronous mode when the input voltage is similar to the output voltage to have high conversion efficiency, and can operate in the asynchronous mode when the input voltage is not similar to the output voltage to reduce the influence caused by the similar input voltage and output voltage.

Although the embodiments of the present invention have been described above, the embodiments are not intended to limit the present invention, and those skilled in the art can make variations on the technical features of the present invention according to the explicit or implicit contents of the present invention, and all such variations may fall within the scope of the patent protection sought by the present invention.

Claims

1. A voltage converter capable of operating in one of a synchronous mode and an asynchronous mode according to an input voltage, the voltage converter comprising:

a voltage detection circuit for generating a detection result according to the input voltage of an input terminal;

a switch control circuit for generating a first switch control signal and a second switch control signal according to the detection result and an output voltage of an output terminal;

a first switch, for intermittently conducting according to the first switch control signal in the synchronous mode and the asynchronous mode;

a second switch, for intermittently conducting according to the second switch control signal in the synchronous mode and for not conducting according to the second switch control signal in the asynchronous mode, wherein the first switch and the second switch are not conducted at the same time; and

and the energy storage circuit is electrically connected with the input end and the output end and used for storing and releasing energy according to the conducting state of the first switch and the second switch so as to adjust the output voltage according to the input voltage.

2. The voltage converter of claim 1, wherein when the voltage detection circuit detects that the difference between the input voltage and the output voltage is below a threshold, the voltage detection circuit outputs the detection result, such that the switch control circuit generates the first switch control signal and the second switch control signal for the asynchronous mode.

3. The voltage converter of claim 2, wherein when the voltage detection circuit detects that the difference between the input voltage and the output voltage is higher than the threshold, the voltage detection circuit outputs the detection result, so that the switch control circuit generates the first switch control signal and the second switch control signal for the synchronous mode.

4. The voltage converter of claim 1, wherein when the voltage detection circuit detects that the difference between the input voltage and the output voltage is higher than a threshold, the voltage detection circuit outputs the detection result to enable the switch control circuit to generate the first switch control signal and the second switch control signal for the synchronous mode.

5. The voltage converter of claim 1, wherein the voltage detection circuit is an analog-to-digital converter or a voltage comparator.

6. The voltage converter of claim 1, wherein the switch control circuit is configured to perform at least one of pulse width modulation and pulse frequency modulation.

7. The voltage converter of claim 1, wherein each of the first switch and the second switch is a transistor, and the second switch comprises a parasitic diode, and the parasitic diode serves as a current path for current to flow through in the asynchronous mode.

8. The voltage converter of claim 1, wherein the energy storage circuit comprises an inductor and a capacitor, the inductor being located between the input terminal and the output terminal, the capacitor being located between the output terminal and a low potential terminal.

9. The voltage converter of claim 8, wherein the voltage converter is a buck converter, the first switch is between the input terminal and a node, the second switch is between the node and the low potential terminal, and the inductor is between the node and the output terminal.

10. The voltage converter of claim 8, wherein the voltage converter is a boost converter, the inductor is located between the input terminal and a node, the first switch is located between the node and the low potential terminal, and the second switch is located between the node and the output terminal.