Voltage conversion device and method thereof

Abstract

The application provides a voltage conversion device and a method thereof. The voltage conversion device includes a charge pump circuit, an operating voltage generation module and a processing module. The charge pump circuit converts an input voltage into an output voltage according to an operating voltage and a frequency signal, and a voltage conversion rate of the charge pump circuit can be dynamically adjusted. The operating voltage generation module is connected to the output voltage and includes a sink diode, and generates the operating voltage according to a conduction state of the sink diode. The processing module is connected to the operating voltage generation module to detect a first current flowing through the sink diode, and adjusts the voltage conversion rate of the charge pump circuit according to the first current.

Description

Technical Field

[0001] This invention relates to a voltage conversion device technology, and more particularly to a voltage conversion device and method thereof that can adjust the voltage conversion according to the input voltage. Background Technology

[0002] The purpose of a voltage conversion device is to convert an input voltage into an output voltage using a default conversion rate, which can be greater than or less than 1. Common voltage conversion devices include charge pumps and switched capacitor power converters.

[0003] With the increasing application of voltage conversion devices, the input voltage of these devices may have a wide voltage range from 2.8V to 20V. For example, after the system containing the voltage conversion device is powered on, the input voltage gradually rises from 0 to the target value. This causes the output voltage of the voltage conversion device to be affected and change significantly, making it unable to stay within the preset range, thus impacting the overall system efficiency.

[0004] In view of this, there is a need for a voltage conversion device and method that can adjust the voltage conversion rate according to the input voltage in order to reduce the variation of the output voltage of the voltage conversion device. Summary of the Invention

[0005] In view of the above problems, the object of the present invention is to provide a voltage conversion device and method thereof.

[0006] To achieve the above objectives, this invention discloses a voltage conversion device comprising a voltage conversion circuit, an operating voltage generation module, and a processing module. The voltage conversion circuit converts an input voltage into an output voltage based on an operating voltage and a frequency signal, wherein the voltage conversion rate of the voltage conversion circuit is dynamically adjustable. The operating voltage generation module includes a Zener diode and generates an operating voltage based on the input voltage and a conduction state of the Zener diode. The processing module is connected to the operating voltage generation module and is used to detect a first current flowing through the Zener diode and adjust the voltage conversion rate of the voltage conversion circuit based on the first current.

[0007] According to one embodiment, when the first current is higher than a reference current, the processing module sets the voltage conversion rate of the voltage conversion circuit to a lower value.

[0008] According to one embodiment, when the first current is not higher than the reference current, the processing module sets the voltage conversion rate of the voltage conversion circuit to a higher value.

[0009] According to one embodiment, the processing module includes a current mirror circuit and a reference current source. The reference current source is used to generate a reference current. A first terminal of the current mirror circuit is coupled to a Zener diode, so that a first current flows through the first terminal. A second terminal of the current mirror circuit is coupled to the reference current source, and the current mirror circuit mirrors the first current to generate a second current that flows through the second terminal. The voltage at the second terminal is used to set the voltage conversion rate of the voltage conversion circuit.

[0010] According to one embodiment, the voltage conversion circuit includes a charge pump circuit, which includes multiple charge pump stages connected in series. The processing module includes a switch and a logic circuit. The switch is connected in parallel with a corresponding charge pump stage of the multiple charge pump stages. The logic circuit is used to selectively turn on the switch to bypass the corresponding charge pump stage, thereby adjusting the voltage conversion rate of the charge pump circuit.

[0011] According to one embodiment, there are multiple reference currents, and the processing module adjusts the voltage conversion rate of the voltage conversion circuit in multiple stages according to whether the first current is greater than each of the multiple reference currents.

[0012] To achieve the above objectives, the present invention discloses a voltage conversion method comprising the following steps: providing a voltage conversion circuit to convert an input voltage into an output voltage based on an operating voltage and a frequency signal, wherein a voltage conversion rate of the voltage conversion circuit can be dynamically adjusted; providing an operating voltage generation module, wherein the operating voltage generation module includes a Zener diode and generates an operating voltage based on the input voltage and a conduction state of the Zener diode; detecting a first current flowing through the Zener diode and adjusting the voltage conversion rate of the voltage conversion circuit based on the first current.

[0013] According to one embodiment, adjusting the voltage conversion rate of the voltage conversion circuit based on the first current includes: setting the voltage conversion rate of the voltage conversion circuit to a lower value when the first current is higher than a reference current; and setting the voltage conversion rate of the voltage conversion circuit to a higher value when the first current is not higher than the reference current.

[0014] According to one embodiment, the voltage conversion method of the present invention further includes: providing a reference current source to generate a reference current; providing a current mirror circuit, wherein a first terminal of the current mirror circuit is coupled to a Zener diode to allow a first current to flow through the first terminal, a second terminal of the current mirror circuit is coupled to the reference current source, and the current mirror circuit mirrors the first current to generate a second current flowing through the second terminal; and adjusting the voltage conversion rate of the voltage conversion circuit according to the voltage at the second terminal of the current mirror circuit.

[0015] According to one embodiment, the voltage conversion circuit includes a charge pump circuit, the charge pump circuit including multiple charge pump stages connected in series, and the voltage conversion method further includes: providing a switch connected in parallel with a corresponding charge pump stage of the multiple charge pump stages; selectively turning on the switch to bypass the corresponding charge pump stage based on whether a first current is higher than a reference current, thereby adjusting the voltage conversion rate of the charge pump circuit.

[0016] According to the above technical solution, the present invention allows the voltage conversion device to adjust the voltage conversion rate according to the input voltage, thereby reducing the variation range of the output voltage of the voltage conversion device. Attached Figure Description

[0017] Figure 1 This is a block diagram of the voltage conversion device of the present invention.

[0018] Figure 2 This is a circuit diagram of one embodiment of the voltage conversion device of the present invention.

[0019] Figure 3 This is a flowchart of the voltage conversion method of the present invention.

[0020] Figure 4 This is a flowchart of one embodiment of the voltage conversion method of the present invention.

[0021] Symbol Explanation

[0022] 10: Voltage conversion device; 11: Voltage conversion circuit; 111: Voltage conversion rate; 112, VPUMP: Output voltage; 12: Operating voltage generation module; 121, ZD: ZN diode; 13: Processing module; 140, VDD: Operating voltage; 141, VIN: Input voltage; 142, CLK: Frequency signal; 231: Current mirror circuit; 232: Operating voltage generation circuit; C1~C4: Capacitors; D1~D4: Diodes; INV1, INV2: Inverters; Ith: Reference current source; M1, M2: Transistors; n1: First terminal; n2: Second terminal; NOR: NOR gate; r1: Resistor; IZD: Current Detailed Implementation

[0023] The following will describe in detail the implementation of the present invention with reference to the accompanying drawings and embodiments, so that the process of how the present invention uses technical means to solve technical problems and achieve technical effects can be fully understood and implemented accordingly.

[0024] To make the features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below with reference to the accompanying drawings. The following description contains specific information relating to exemplary embodiments of the present invention. The accompanying drawings and detailed description are merely exemplary embodiments. However, the present invention is not limited to these exemplary embodiments. Other variations and embodiments of the invention will occur to those skilled in the art. Unless otherwise stated, the same or corresponding components in the drawings are indicated by the same or corresponding reference numerals. Furthermore, the drawings and illustrations in the present invention are generally not drawn to scale and are not intended to correspond to actual relative dimensions.

[0025] Please see Figure 1 , Figure 1 This is a block diagram of the voltage conversion device of the present invention. Figure 1 As shown, the voltage conversion device 10 includes a voltage conversion circuit 11, an operating voltage generation module 12, and a processing module 13. The voltage conversion circuit 11 converts an input voltage 141 into an output voltage 112 based on an operating voltage 140 and a frequency signal 142. The voltage conversion rate 111 of the voltage conversion circuit 11 is dynamically adjustable. The operating voltage generation module 12 includes a Zener diode 121 and generates the operating voltage 140 based on the input voltage 141 and a conduction state of the Zener diode 121. The processing module 13 is connected to the operating voltage generation module 12 and detects the current flowing through the Zener diode 121, adjusting the voltage conversion rate 111 of the voltage conversion circuit 11 based on the current flowing through the Zener diode 121.

[0026] In one embodiment, when the current flowing through the Zener diode 121 is higher than a reference current (i.e., the Zener diode 121 is turned on), the processing module 13 sets the voltage conversion rate 111 of the voltage conversion circuit 11 to a lower value. When the current flowing through the Zener diode 121 is not higher than the reference current (i.e., the Zener diode 121 is not turned on), the processing module 13 sets the voltage conversion rate 111 of the voltage conversion circuit 11 to a higher value. For example, during the process of the input voltage 141 gradually increasing from 0, when the Zener diode 121 is not yet turned on (that is, the Zener diode 121 has not entered the breakdown state), the operating voltage 140 will increase with the input voltage 141. Since the value of the operating voltage 140 is low at this stage, in order to maintain the output voltage within the default range, the voltage conversion circuit 11 needs a higher voltage conversion rate 111. The voltage conversion rate 111 of the voltage conversion circuit 11 is set to a higher value. For example, assuming that the voltage conversion rate 111 of the voltage conversion circuit 11 can be set to 2 times or 3 times, when the current flowing through the Zener diode 121 is not higher than the reference current, the processing module 13 sets the voltage conversion rate 111 of the voltage conversion circuit 11 to 3 times.

[0027] When the input voltage 141 rises to the point that the Zener diode 121 enters the breakdown state and turns on, the operating voltage 140 will be clamped by the breakdown voltage of the Zener diode 121. Since the value of the operating voltage 140 is high at this stage, in order to keep the output voltage 112 within the default range, the voltage conversion circuit 11 needs a lower voltage conversion rate 111. The voltage conversion rate 111 of the voltage conversion circuit 11 is set to a lower value, for example, twice.

[0028] In one embodiment, the voltage conversion circuit 11 may be a charge pump circuit or a switched capacitor power conversion circuit.

[0029] Please see Figure 2 , Figure 2 This is a circuit diagram of one embodiment of the voltage conversion device of the present invention. Figure 2 As shown, the voltage conversion device includes a charge pump circuit, an operating voltage generation circuit 232, a current mirror circuit 231, a reference current source Ith, and a selection circuit. It should be noted that this embodiment uses a Dickson charge pump circuit to implement the voltage conversion circuit, but the invention is not limited thereto. Figure 1 The processing module 13 is implemented using a current mirror circuit 231, a reference current source Ith, and a selection circuit. The selection circuit includes a NOR gate and a switch (implemented using a transistor M2).

[0030] Figure 2 The charge pump circuit comprises multiple charge pump stages connected in series and inverters INV1 and INV2 connected in series. Each charge pump stage includes a diode and a capacitor. Inverters INV1 and INV2 operate with an operating voltage VDD. The input of inverter INV1 receives a frequency signal CLK. Diodes D1 to D4 are connected in series. The anode of diode D1 receives the input voltage VIN. Capacitor C1 is connected between the cathode of diode D1 and the output of inverter INV1. Capacitor C2 is connected between the cathode of diode D2 and the output of inverter INV2. Capacitor C3 is connected between the cathode of diode D3 and the output of the NOR gate. Capacitor C4 is connected between the cathode of diode D4 and ground. The voltage at the cathode of diode D4 is used as the output voltage VPUMP.

[0031] The switch (i.e., transistor M2) in the selection circuit is connected in parallel with diode D4. In other words, when switch M2 is on, diode D4 is bypassed, and the voltage conversion efficiency of the charge pump circuit is lower, for example, twice as high. When switch M2 is off, diode D4 is not bypassed, and the voltage conversion efficiency of the charge pump circuit is higher, for example, three times as high.

[0032] The operating voltage generation circuit 232 includes a Zener diode ZD, a resistor r1, and a transistor M1. Resistor r1 is connected between the first terminal n1 of the current mirror circuit 231 and the cathode of the Zener diode ZD. The reference current source Ith is connected to the second terminal n2 of the current mirror circuit 231. The current mirror circuit 231 mirrors the first current flowing through the first terminal n1 to generate a mirrored current at the second terminal n2. The mirrored current and the first current can be proportional according to the design; here, a 1:1 ratio is used. The first current is the current IZD flowing through the Zener diode ZD.

[0033] When power is supplied to the voltage conversion device, the input voltage VIN gradually rises from 0. During the period when the input voltage VIN is below the breakdown voltage of the Zener diode ZD, the Zener diode ZD does not enter the breakdown state (i.e., Zener diode 121 is not yet conducting), and the current IZD is very small and negligible. Therefore, the operating voltage VDD is the input voltage VIN minus the critical voltage of transistor M1, and is linked to the input voltage VIN. Because the current IZD is very small, the mirror current is also very small and less than the current of the reference current source Ith. Therefore, the voltage at the second terminal n2 is at a logic low level, causing the switch (i.e., transistor M2) to turn off. Diode D4 is not bypassed, and the voltage conversion efficiency of the charge pump circuit is unaffected (i.e., the voltage conversion efficiency of the charge pump circuit is set to a higher value).

[0034] When the input voltage VIN is higher than the breakdown voltage of the Zener diode ZD, the Zener diode ZD enters the breakdown state (i.e., Zener diode 121 conducts), and the current IZD increases significantly. The gate voltage of transistor M1 is clamped at the breakdown voltage of the Zener diode ZD. Therefore, the operating voltage VDD is the breakdown voltage of the Zener diode ZD minus the critical voltage of transistor M1, and is not linked to the input voltage VIN. Because the current IZD increases significantly, the mirror current increases and is greater than the current of the reference current source Ith. Therefore, the voltage at the second terminal n2 is at a logic high level, causing the switch (i.e., transistor M2) to conduct, and diode D4 to be bypassed. The voltage conversion efficiency of the charge pump circuit is affected and reduced (i.e., the voltage conversion efficiency of the charge pump circuit is set to a lower value). Based on the above explanation, users can design an appropriate reference current source Ith, allowing the charge pump circuit to use a higher voltage slew rate when the Zener diode ZD is not conducting and the operating voltage VDD is low, and a lower voltage slew rate when the Zener diode ZD is conducting and the operating voltage VDD is high. This keeps the output voltage VPUMP of the charge pump circuit within its default range. For example, with an input voltage range of 2.8V to 20V and an operating voltage VDD range of 2.3V to 5V, the voltage slew rate of the charge pump circuit can be switched to 2x or 3x respectively.

[0035] In one embodiment, when the voltage conversion circuit can select more than two voltage conversion rates (e.g., three or four voltage conversion rates), the aforementioned reference current sources can be multiple to provide reference currents of different magnitudes. The selection circuit may include multiple NOR gates and multiple switches to adjust the voltage conversion rate of the voltage conversion circuit in multiple stages based on whether the mirrored current (i.e., the current IZD flowing through the ZD diode) is greater than the multiple reference currents respectively. For example, in one embodiment, a first switch is connected in parallel with a diode D3, and a second switch is connected in parallel with a diode D4. The mirrored current is compared with a first reference current and a second reference current, respectively. A first NOR gate receives the comparison result of the first reference current and controls the first switch, and a second NOR gate receives the comparison result of the second reference current and controls the second switch, thereby achieving multi-stage adjustment of the voltage conversion rate.

[0036] Please see Figure 3 , Figure 3 This is a flowchart of the voltage conversion method of the present invention. Figure 3 and Figure 1 As shown, the voltage conversion method of the present invention may include the following steps.

[0037] Step S31: A voltage conversion circuit 11 is provided. The voltage conversion circuit 11 converts an input voltage 141 into an output voltage 112 based on an operating voltage 140 and a frequency signal 142. The voltage conversion rate 111 of the voltage conversion circuit 11 can be dynamically adjusted. In one embodiment, the voltage conversion circuit 11 may be a charge pump circuit or a switched capacitor power conversion circuit.

[0038] Step S32: Provide an operating voltage generation module 12, which includes a Zener diode 121 and generates an operating voltage 140 based on the input voltage 141 and a conduction state of the Zener diode 121.

[0039] Step S33: Detect a first current flowing through the Zener diode 121, and adjust the voltage conversion rate 111 of the voltage conversion circuit 11 according to the first current.

[0040] In one embodiment, in step S33, when the first current is higher than a reference current, the voltage conversion rate 111 of the voltage conversion circuit 11 is set to a lower value, and when the first current is not higher than the reference current, the voltage conversion rate 111 of the voltage conversion circuit 11 is set to a higher value.

[0041] In one embodiment, step S33 may further include: providing a reference current source to generate a reference current, and providing a current mirror circuit, wherein a first terminal of the current mirror circuit is coupled to a Zener diode 121 to allow a first current to flow through the first terminal, a second terminal of the current mirror circuit 231 is coupled to the reference current source, and the current mirror circuit 231 mirrors the first current to generate a second current flowing through the second terminal; and adjusting the voltage conversion rate 111 of the voltage conversion circuit 11 according to the voltage at the second terminal of the current mirror circuit 231.

[0042] Please see Figure 4 , Figure 4 This is a flowchart illustrating one embodiment of the voltage conversion method of the present invention. Figure 4 and Figure 2 As shown, one embodiment of the voltage conversion method of the present invention may include the following steps.

[0043] Step S41: A charge pump circuit is provided, which includes multiple charge pump stages connected in series. The charge pump circuit can convert an input voltage VIN into an output voltage VPUMP based on an operating voltage VDD and a frequency signal CLK.

[0044] Step S42: A transistor M2 and a NOR gate are provided. Transistor M2 is connected in parallel with diode D4 of the charge pump stage. The conduction state of transistor M2 can adjust the voltage conversion rate of the charge pump circuit. For example, when transistor M2 is on, diode D4 is bypassed, causing the voltage conversion rate of the charge pump circuit to be affected and decrease; when transistor M2 is not on, diode D4 is not bypassed, and the voltage conversion rate of the charge pump circuit remains unchanged.

[0045] Step S43: An operating voltage generation circuit 232 is provided. The operating voltage generation circuit 232 includes a Zener diode ZD, a resistor r1, and a transistor M1. The operating voltage generation circuit 232 can generate an operating voltage VDD based on the input voltage VIN and a conduction state of the Zener diode ZD. For example, when the Zener diode ZD is not conducting (i.e., the Zener diode ZD is not in the breakdown state), the operating voltage VDD is the input voltage VIN minus the critical voltage of the transistor M1; when the Zener diode ZD is conducting (i.e., the Zener diode ZD is in the breakdown state), the operating voltage VDD is the breakdown voltage of the Zener diode ZD minus the critical voltage of the transistor M1.

[0046] Step S44: A current mirror circuit 231 and a reference current source Ith are provided to detect the current IZD flowing through the Zener diode ZD and adjust the voltage conversion rate 111 of the voltage conversion circuit 11 according to the current IZD. In this embodiment, a resistor r1 is connected between the first terminal n1 of the current mirror circuit 231 and the cathode of the Zener diode ZD, and the reference current source Ith is connected to the second terminal n2 of the current mirror circuit 231. The current mirror circuit 231 can mirror the first current flowing through the first terminal n1 to generate a mirrored current at the second terminal n2. The mirrored current and the first current can be proportional according to the design, and are described here as a 1:1 ratio. The first current is the current IZD flowing through the Zener diode ZD.

[0047] Step S45: Depending on whether the current flowing through the Zener diode ZD is higher than the current of the reference current source, the switch (i.e., transistor M2) is selectively turned on to bypass the corresponding charge pump stage, thereby adjusting the voltage conversion rate of the charge pump circuit.

[0048] In this embodiment, during the period when the input voltage VIN is not higher than the breakdown voltage of the Zener diode ZD, the Zener diode ZD does not enter the breakdown state (i.e., the Zener diode 121 is not yet turned on), and the current IZD is very small and negligible. Therefore, the operating voltage VDD is the input voltage VIN minus the critical voltage of transistor M1, and is linked to the input voltage VIN. Since the current IZD is very small, the mirror current is also very small and less than the current of the reference current source Ith. Therefore, the voltage at the second terminal n2 is at a logic low level, causing the switch (i.e., transistor M2) to be turned off. Diode D4 is not bypassed, and the voltage conversion efficiency of the charge pump circuit is not affected (i.e., the voltage conversion efficiency of the charge pump circuit is set to a higher value).

[0049] When the input voltage VIN is higher than the breakdown voltage of the Zener diode ZD, the Zener diode ZD enters the breakdown state (i.e., Zener diode 121 conducts), and the current IZD increases significantly. The gate voltage of transistor M1 is clamped at the breakdown voltage of the Zener diode ZD. Therefore, the operating voltage VDD is the breakdown voltage of the Zener diode ZD minus the critical voltage of transistor M1, and is not linked to the input voltage VIN. Because the current IZD increases significantly, the mirror current increases and is greater than the current of the reference current source Ith. Therefore, the voltage at the second terminal n2 is at a logic high level, causing the switch (i.e., transistor M2) to conduct, and diode D4 to be bypassed. The voltage conversion efficiency of the charge pump circuit is affected and reduced (i.e., the voltage conversion efficiency of the charge pump circuit is set to a lower value).

[0050] Although the present invention has been disclosed above with reference to the foregoing embodiments, it is not intended to limit the present invention. Any person skilled in the art may make some modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the scope of patent protection of the present invention shall be determined by the claims appended to the present invention.

Claims

1. A voltage conversion device, characterized in that, include: A voltage conversion circuit converts an input voltage into an output voltage based on an operating voltage and a frequency signal, wherein the voltage conversion rate of the voltage conversion circuit can be dynamically adjusted. An operating voltage generation module includes a Zener diode and generates the operating voltage based on the input voltage and a conduction state of the Zener diode; as well as A processing module, connected to the operating voltage generation module, is used to detect a first current flowing through the Zener diode and adjust the voltage conversion rate of the voltage conversion circuit according to the first current.

2. The voltage conversion device as described in claim 1, characterized in that, When the first current is higher than a reference current, the processing module sets the voltage conversion rate of the voltage conversion circuit to a lower value.

3. The voltage conversion device as described in claim 2, characterized in that, When the first current is not higher than the reference current, the processing module sets the voltage conversion rate of the voltage conversion circuit to a higher value.

4. The voltage conversion device as described in claim 2, characterized in that, The processing module includes a current mirror circuit and a reference current source. The reference current source is used to generate the reference current. The first terminal of the current mirror circuit is coupled to the Zener diode, so that the first current flows through the first terminal. The second terminal of the current mirror circuit is coupled to the reference current source, and the current mirror circuit mirrors the first current to generate a second current that flows through the second terminal. The voltage at the second terminal is used to set the voltage conversion rate of the voltage conversion circuit.

5. The voltage conversion device as described in claim 1, characterized in that, The voltage conversion circuit includes a charge pump circuit comprising multiple charge pump stages connected in series. The processing module includes a switch and a logic circuit. The switch is connected in parallel with a corresponding charge pump stage of the multiple charge pump stages. The logic circuit is used to selectively turn on the switch to bypass the corresponding charge pump stage, thereby adjusting the voltage conversion rate of the charge pump circuit.

6. The voltage conversion device as described in claim 2, characterized in that, The reference current is multiple, and the processing module adjusts the voltage conversion rate of the voltage conversion circuit in multiple stages according to whether the first current is greater than each of the multiple reference currents.

7. A voltage conversion method, characterized in that, include: A voltage conversion circuit is provided to convert an input voltage into an output voltage based on an operating voltage and a frequency signal, wherein the voltage conversion rate of the voltage conversion circuit can be dynamically adjusted. An operating voltage generation module is provided, wherein the operating voltage generation module includes a Zener diode and generates the operating voltage according to the input voltage and a conduction state of the Zener diode; A first current flowing through the Zener diode is detected, and the voltage conversion rate of the voltage conversion circuit is adjusted according to the first current.

8. The voltage conversion method as described in claim 7, characterized in that, Adjusting the voltage conversion rate of the voltage conversion circuit according to the first current includes: When the first current is higher than a reference current, the voltage conversion rate of the voltage conversion circuit is set to a lower value; and When the first current is not higher than the reference current, the voltage conversion rate of the voltage conversion circuit is set to a relatively high value.

9. The voltage conversion method as described in claim 8, characterized in that, Also includes: A reference current source is provided to generate the reference current; A current mirror circuit is provided, wherein a first terminal of the current mirror circuit is coupled to the Zener diode, allowing a first current to flow through the first terminal, a second terminal of the current mirror circuit is coupled to the reference current source, and the current mirror circuit mirrors the first current to generate a second current flowing through the second terminal. as well as The voltage conversion rate of the voltage conversion circuit is adjusted according to the voltage at the second terminal of the current mirror circuit.

10. The voltage conversion method as described in claim 9, characterized in that, The voltage conversion circuit includes a charge pump circuit, which comprises multiple charge pump stages connected in series. The voltage conversion method further includes: A switch is provided in parallel with a corresponding charge pump stage of the plurality of charge pump stages; the switch is selectively turned on to bypass the corresponding charge pump stage based on whether the first current is higher than the reference current, thereby adjusting the voltage conversion rate of the charge pump circuit.

Images