阅读说明：本技术 一种具有钳位限流功能的高压ldo电路 (High-voltage low dropout regulator (LDO) circuit with clamping current-limiting function ) 是由 陈玉鹏 李林喜 晋丁亥 李江山 于 2021-06-30 设计创作，主要内容包括：本发明提出了一种具有钳位限流功能的高压LDO电路,用于解决传统高压LDO面积过大、性能不高、输出驱动管栅源电压过高易损坏以及LDO的输出限流问题。本发明包括3个NMOS管M1～M3,4个电阻R1～R4、电容C1、4个稳压二极管D1～D4和误差放大器AMP；在输入端通过三个稳压二极管串联将输入高电压降至一个低压范围,可采用更低耐压器件设计电路,其输出驱动管的栅极和源极接入稳压二极管采用其稳压电压值达到限制输出电流的目的。提高驱动能力的同时减少光罩层,电路简单并且可降低成本。(The invention provides a high-voltage LDO (low dropout regulator) circuit with a clamping current-limiting function, which is used for solving the problems that the traditional high-voltage LDO has overlarge area and low performance, the grid-source voltage of an output driving tube is overhigh and is easy to damage and the output current-limiting of the LDO. The invention comprises 3 NMOS transistors M1-M3, 4 resistors R1-R4, a capacitor C1, 4 voltage stabilizing diodes D1-D4 and an error amplifier AMP; the input high voltage is reduced to a low voltage range by connecting three voltage stabilizing diodes in series at the input end, a circuit can be designed by adopting a lower voltage-resistant device, and the grid electrode and the source electrode of the output driving tube are connected into the voltage stabilizing diodes to achieve the purpose of limiting the output current by adopting the voltage stabilizing voltage value. The driving capability is improved and the mask layer is reduced, the circuit is simple and the cost can be reduced.)

1. A high-voltage LDO circuit with a clamping current-limiting function is characterized by comprising a first NMOS tube M1, a second NMOS tube M2, a third NMOS tube M3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a first voltage-stabilizing diode D1, a second voltage-stabilizing diode D2, a third voltage-stabilizing diode D3, a fourth voltage-stabilizing diode D4 and an error amplifier AMP; wherein the content of the first and second substances,

the drain of the first NMOS transistor M1 and the first resistor R1 are connected as an input terminal VIN; the input end VIN is connected with the reverse end of the first voltage-stabilizing diode D1 and the gate of the second NMOS transistor M2 sequentially through a first resistor R1 and a second resistor R2; the input end VIN is connected to the gate of the first NMOS transistor M1 through a first resistor R1;

the forward terminal of the first zener diode D1 is connected to the reverse terminal of the second zener diode D2; the forward terminal of the second zener diode D2 is connected to the reverse terminal of the third zener diode D3; the forward terminal of the third zener diode D3 is grounded GND;

the source electrode of the first NMOS transistor M1, the drain electrode of the second NMOS transistor M2 and the drain electrode of the third NMOS transistor M3 are connected to form a power supply end VinH of the third NMOS transistor M3;

the source electrode of the second NMOS tube M2 is connected with the power supply end VHC of the error amplifier AMP; the positive input end of the error amplifier AMP is connected with a reference voltage VREF; the inverting input terminal of the error amplifier AMP is grounded to GND through a fourth resistor R4; the reverse input end of the error amplifier AMP is connected with the forward end of the fourth voltage-stabilizing diode D4 through a first capacitor C1 to serve as an output end Vout;

the output end of the error amplifier AMP and the reverse direction of the fourth voltage stabilizing diode D4 are connected with the grid electrode of the third NMOS tube M3; the source of the third NMOS transistor M3 is connected to the forward terminal of the fourth zener diode D4, and also connected to GND sequentially through the third resistor R3 and the fourth resistor R4.

Technical Field

The invention relates to the electronic circuit technology, in particular to a high-voltage low dropout regulator (LDO) circuit with a clamping current limiting function.

Background

The LDO (low dropout regulator) is a core module in power management, and can realize voltage conversion and output a stable power voltage. With the development of the scale of integrated circuits, electronic devices are smaller in size and weight, which puts higher and higher demands on miniaturization of power supply circuits. If the area of the LDO can be reduced well, the area of the chip can be effectively reduced. Therefore, the requirement of miniaturization of the power supply circuit is met, and the chip cost is well controlled.

The basic structure of the LDO comprises: the feedback resistor network, the output driving tube and the error amplifier. In order to meet the requirement of operating voltage in high-voltage application, a high-voltage MOS device is generally required to construct an analog circuit, and the performance of the high-voltage device is generally inferior to that of a low-voltage device, and a large chip area is often required, so that the area of a designed high-voltage LDO circuit is too large. Meanwhile, the output driving tube is used as an important component in the LDO topological structure, if the grid-source voltage is overlarge and exceeds the rated withstand voltage value, the output driving tube can be broken down and damaged. The gate-source withstand voltage of the output driving tube generally depends on the thickness of the gate oxide layer. The thicker the gate oxide, the higher the gate-source withstand voltage, and the current driving capability of the driving transistor is reduced. In order to overcome this problem, a thick gate oxide power device is generally used to ensure sufficient gate-source withstand voltage of the driving transistor, and the thick gate oxide power device has low current driving capability and high cost. Therefore, it is necessary to design a protection circuit of the output driving transistor to limit the gate-source voltage, so that a thin gate oxide power device with better driving performance can be used as the output driving transistor.

When the LDO supplies power to a load, the LDO regulator may be damaged if an output short circuit occurs or the load current is too large. Especially in the case of short circuit, the LDO has excessive current flowing through the output driving transistor, which may burn the output driving transistor. Therefore, it is necessary to design a current limiting circuit for LDO regulation, which can limit the output current within the tolerable range of the driving tube in time under the condition of overload or short circuit.

Disclosure of Invention

In order to solve the problems that the traditional high-voltage LDO is overlarge in area, low in performance, too high in grid-source voltage of an output driving tube and easy to damage and the output current of the LDO is limited, the invention provides a high-voltage LDO circuit with a clamping current-limiting function.

In order to achieve the purpose, the invention provides the following technical scheme: the high-voltage power amplifier comprises a first NMOS transistor M1, a second NMOS transistor M2, a third NMOS transistor M3, a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a first voltage-stabilizing diode D1, a second voltage-stabilizing diode D2, a third voltage-stabilizing diode D3, a fourth voltage-stabilizing diode D4 and an error amplifier AMP; wherein the content of the first and second substances,

the drain of the first NMOS transistor M1 and the first resistor R1 are connected as an input terminal VIN; the input end VIN is connected with the reverse end of the first voltage-stabilizing diode D1 and the gate of the second NMOS transistor M2 sequentially through a first resistor R1 and a second resistor R2; the input end VIN is connected to the gate of the first NMOS transistor M1 through a first resistor R1;

the forward terminal of the first zener diode D1 is connected to the reverse terminal of the second zener diode D2; the forward terminal of the second zener diode D2 is connected to the reverse terminal of the third zener diode D3; the forward terminal of the third zener diode D3 is grounded GND;

the source electrode of the first NMOS transistor M1, the drain electrode of the second NMOS transistor M2 and the drain electrode of the third NMOS transistor M3 are connected to form a power supply end VinH of the third NMOS transistor M3;

the source electrode of the second NMOS tube M2 is connected with the power supply end VHC of the error amplifier AMP; the positive input end of the error amplifier AMP is connected with a reference voltage VREF; the inverting input terminal of the error amplifier AMP is grounded to GND through a fourth resistor R4; the reverse input end of the error amplifier AMP is connected with the forward end of the fourth voltage-stabilizing diode D4 through a first capacitor C1 to serve as an output end Vout;

the output end of the error amplifier AMP and the reverse direction of the fourth voltage stabilizing diode D4 are connected with the grid electrode of the third NMOS tube M3; the source of the third NMOS transistor M3 is connected to the forward terminal of the fourth zener diode D4, and also connected to GND sequentially through the third resistor R3 and the fourth resistor R4.

The invention has the beneficial effects that:

1. the input high voltage is reduced to a low voltage range at the input end through the series connection of three voltage stabilizing diodes, a circuit can be designed by adopting a lower voltage-resistant device, the circuit performance can be optimized, and the layout area can be reduced.

2. The output driving tube M3 adopts a voltage stabilizing diode to clamp and protect the grid source voltage resistance and simultaneously realize the purpose of current limiting, compared with the thick grid oxygen power device, the driving capability can be improved, simultaneously, the photomask layer is reduced, the circuit is simple, and the cost can be reduced.

Drawings

Fig. 1 is a schematic diagram of an implementation of a high voltage LDO circuit with a clamp current limiting function according to the present invention.

Detailed Description

The technical scheme of the invention is described in detail in the following with the accompanying drawings:

the invention discloses a high-voltage LDO circuit with a clamping current-limiting function, which is shown in figure 1 and comprises: 3 NMOS transistors M1, M2, M3, 4 resistors R1, R2, R3, R4, a capacitor C1, 4 zener diodes D1, D2, D3, D4 and an error amplifier AMP; wherein the content of the first and second substances,

the drain of the first NMOS transistor M1 and the first resistor R1 are connected as an input terminal VIN; the input end VIN is connected with the reverse end of the first voltage-stabilizing diode D1 and the gate of the second NMOS transistor M2 sequentially through a first resistor R1 and a second resistor R2; the input end VIN is connected to the gate of the first NMOS transistor M1 through a first resistor R1;

the forward terminal of the first zener diode D1 is connected to the reverse terminal of the second zener diode D2; the forward terminal of the second zener diode D2 is connected to the reverse terminal of the third zener diode D3; the forward terminal of the third zener diode D3 is grounded GND;

the source electrode of the first NMOS transistor M1, the drain electrode of the second NMOS transistor M2, and the drain electrode of the third NMOS transistor M3 are connected to a power supply terminal VinH of the third NMOS transistor M3, and the third NMOS transistor M3 serves as an output driving transistor.

The source electrode of the second NMOS tube M2 is connected with the power supply end VHC of the error amplifier AMP; the positive input end of the error amplifier AMP is connected with a reference voltage VREF; the inverting input terminal of the error amplifier AMP is grounded to GND through R4; the reverse input end of the error amplifier AMP is connected with the forward end of the fourth voltage stabilizing diode D4 through a capacitor C1 to serve as an output end Vout;

the output end of the error amplifier AMP and the reverse direction of the fourth voltage stabilizing diode D4 are connected with the grid electrode of the third NMOS tube M3; the source of the third NMOS transistor M3 is connected to the forward terminal of the third zener diode D4, and also connected to GND sequentially through the third resistor R3 and the fourth resistor R4.

The working principle of the invention is as follows:

the input high voltage is reduced to a low voltage range through the series connection of three voltage stabilizing diodes at the input end, and VinH and VHC output by a first NMOS tube M1 and a second NMOS tube M2 respectively supply power to a rear-stage driving tube M3 and an error amplifier AMP; the output driving tube adopts the voltage-stabilizing characteristic of a voltage-stabilizing diode D4 to clamp the gate-source voltage of the output driving tube M3, so that the purpose of output current limiting is achieved while the gate-source voltage of the output driving tube is protected against voltage. Compared with a thick gate oxide power device, the driving capability can be improved, meanwhile, the mask layer is reduced, the circuit is simple, and the cost can be reduced. The final input voltage VIN of the circuit can reach 100V, the output voltage can reach 11V, and the output current is 50 mA.

While the foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.