A charge pump circuit for DC-to-DC conversion

Abstract

The present invention belongs to the technical field of power integrated circuits, and specifically relates to a charge pump circuit for DC-DC conversion. After the capacitor is fully charged with the input voltage Vs, the two ends are disconnected from the original charging circuit, the negative plate of the capacitor is connected to the original input voltage Vs, and at this time the value of the positive plate of the capacitor will be raised. That is, charging the capacitor, removing the capacitor from the charging circuit to isolate the charged charge, and then connecting it to another circuit to transfer the just-isolated charge. The present invention utilizes the charging and discharging characteristics of the capacitor to obtain an output voltage after raising the input voltage, realizing the DC-DC voltage conversion. The structure of the present invention avoids the problem that the reverse diode in the common charge pump circuit is difficult to integrate, and simplifies the chip pins.

Description

Technical Field

[0001] The present invention belongs to the technical field of power integrated circuits, and specifically relates to a charge pump circuit for direct current to direct current conversion. Background Art

[0002] In a high-voltage gate driver chip, there are two different channels: the high-side and the low-side. The source of the MOS transistor in the low-side channel is grounded, so only a small gate voltage is required to turn on the MOS transistor; however, the source of the MOS transistor in the high-side channel is connected to a floating ground, and the maximum value of the floating ground can reach dozens of volts. At this time, a high gate voltage is required to turn on the MOS. Therefore, a circuit is needed to generate the voltage for turning on the high-side power transistor. Summary of the Invention

[0003] In response to the above requirements, the present invention proposes a charge pump circuit for direct current to direct current conversion, which can meet the driving requirements for different power transistors.

[0004] The technical solution of the present invention is as follows:

[0005] A charge pump circuit for direct current to direct current conversion, characterized in that it includes a first NMOS transistor, a second NMOS transistor, a third NMOS transistor, a fourth NMOS transistor, a first capacitor, a first resistor, a first Zener diode, a second Zener diode, and a first diode; wherein, the drain of the second NMOS transistor is connected to the power supply, its gate is connected to a first bias voltage, and its source is connected to the anode of the first diode; the cathode of the first diode is connected to one end of the first capacitor and the source of the third NMOS transistor; the other end of the first capacitor is connected to the source of the fourth NMOS transistor and the drain of the first NMOS transistor; the drain of the fourth NMOS transistor is connected to the power supply, and its gate is connected to a second bias voltage; the gate of the first NMOS transistor is connected to the first bias voltage, and its source is connected to one end of the first resistor and the anode of the first Zener diode; the other end of the first resistor is grounded; the cathode of the first Zener diode is connected to the anode of the second Zener diode, and the cathode of the second Zener diode is connected to the power supply; the gate of the third NMOS transistor is connected to the second bias voltage; the drain of the third NMOS transistor is the high-side output terminal of the charge pump circuit, and the source of the first NMOS transistor is the low-side output terminal of the charge pump circuit.

[0006] Defining the high-side output terminal as Vb, the low-side output terminal as Vcharge, and the power supply as Vs, the relationship between Vb and Vcharge is Vb - Vs = -(Vcharge - Vs).

[0007] The beneficial effects of the present invention are as follows: 1) This circuit can generate a DC output voltage higher than the DC input voltage; 2) It avoids the problem that a high reverse breakdown voltage diode is required in a common charge pump circuit, but it is difficult to integrate this diode; 3) There is no need to provide an input voltage externally to the chip. The output of the driver is directly used as the input of this circuit, which can reduce one chip pin. Brief Description of the Drawings

[0008] Figure 1 It is a structural implementation diagram of a charge pump circuit for DC - to - DC conversion proposed by the present invention. Detailed Embodiment

[0009] The technical solution of the present invention will be described below with reference to the drawings:

[0010] After the capacitor is fully charged with the input voltage Vs in the present invention, the two ends are disconnected from the original charging circuit. The negative plate of the capacitor is connected to the original input voltage Vs. At this time, the value of the positive plate of the capacitor will be raised. That is, charging the capacitor, removing the capacitor from the charging circuit to isolate the charged charge, and then connecting it to another circuit to transfer the just - isolated charge. Figuratively speaking, the capacitor that transfers the charge can be regarded as a "bucket filled with electrons". Fill this bucket from a large water tank, close the faucet, and then pour the water in the bucket into a large water tank.

[0011] Figure 1 It is a charge pump circuit for DC - to - DC conversion. The charge pump circuit module includes: the first NMOS transistor NM0, the second NMOS transistor NM1, the third NMOS transistor NM2, the fourth NMOS transistor NM3, the first capacitor C1, the first resistor R0, the first Zener diode D1, the second Zener diode D2, and the first diode D3.

[0012] The power supply node Vs is connected to the cathode of the second Zener diode D2. The anode of the second Zener diode D2 is connected to the cathode of the first Zener diode D1. The anode of the first Zener diode D1 is connected to the low-side output node Vcharge. Vcharge is connected to the first port of the first resistor R0. The second port of the first resistor R0 is grounded. Vs is connected to the drain of the fourth NMOS transistor NM3. The gate of the fourth NMOS transistor NM3 is connected to the vbias2 node. The source of the fourth NMOS transistor NM3 is connected to the drain of the first NMOS transistor NM0. The gate of the first NMOS transistor NM0 is connected to the vbias1 node. The source of the first NMOS transistor NM0 is connected to Vcharge. Vs is connected to the drain of the second NMOS transistor NM1. The gate of the second NMOS transistor NM1 is connected to the vbias1 node. The source of the second NMOS transistor NM1 is connected to the anode of the first diode D3. The cathode of the first diode D3 is connected to the first port of the first capacitor C1. The second port of the first capacitor C1 is connected to the drain of the first NMOS transistor NM0. The high-side output terminal node Vb is connected to the drain of the third NMOS transistor NM2. The gate of the third NMOS transistor NM2 is connected to the vbias2 node. The source of the third NMOS transistor NM2 is connected to the cathode of the first diode D3.

[0013] The working principle of the present invention is as follows:

[0014] First, set vbias1 to high and vbias2 to low. NM0 and NM1 are turned on, and NM2 and NM3 are turned off. At this time, Vs charges the positive plate of the capacitor C1 through NM1-D3. The negative plate of C1 is connected to Vcharge through NM0. After being fully charged, set vbias2 to high and vbias1 to low. NM2 and NM3 are turned on, and NM0 and NM1 are turned off. At this time, the negative plate of C1 is connected to Vs through NM3, and the voltage of the negative plate is raised. The positive plate of C1 is connected to the output Vb through NM2.

[0015] According to the circuit connection relationship, the value of Vcharge is equal to the sum of the voltages of the Zener diodes D1 and D2. Therefore, the voltage across the capacitor after being fully charged is the difference between Vs and Vcharge. When the circuit connection changes, the difference between the voltage value of the output Vb and Vcharge is twice the sum of the voltages of D1 and D2. The difference between Vb and ground is Vs plus the sum of the voltages of D1 and D2. By setting different numbers of series-connected Zener diodes, different output Vb values can be obtained.

[0016] D3 is connected to the source of NM1 to ensure that the current only flows through NM2 when the capacitor is connected to the output Vb, preventing the current from flowing through NM1. Vs is directly introduced from the output of the driving transistor inside the chip.

Claims

1. A charge pump circuit for DC-DC conversion, characterized in that, it includes a first NMOS transistor, a second NMOS transistor, a third NMOS transistor, a fourth NMOS transistor, a first capacitor, a first resistor, a first Zener diode, a second Zener diode, and a first diode; wherein, the drain of the second NMOS transistor is connected to the power supply, its gate is connected to a first bias voltage, and its source is connected to the anode of the first diode; the cathode of the first diode is connected to one end of the first capacitor and the source of the third NMOS transistor; the other end of the first capacitor is connected to the source of the fourth NMOS transistor and the drain of the first NMOS transistor; the drain of the fourth NMOS transistor is connected to the power supply, its gate is connected to a second bias voltage; the gate of the first NMOS transistor is connected to the first bias voltage, its source is connected to one end of the first resistor and the anode of the first Zener diode; the other end of the first resistor is grounded; the cathode of the first Zener diode is connected to the anode of the second Zener diode, and the cathode of the second Zener diode is connected to the power supply; the gate of the third NMOS transistor is connected to the second bias voltage; the drain of the third NMOS transistor is the high-side output terminal of the charge pump circuit, and the source of the first NMOS transistor is the low-side output terminal of the charge pump circuit.

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