A switch chip capable of replacing a PMOS tube

Abstract

The present invention provides a switch chip capable of replacing a PMOS tube, comprising an input pin, an output pin, and a control pin, which can respectively replace the source, drain, and gate of the PMOS tube equivalently, and a control circuit in the chip comprises an NMOS tube, a GND pin in the chip, a floating ground detection module, a charge pump, and a charge discharge module, wherein the drain and source of the NMOS tube are respectively connected to the input pin and the output pin, the gate of the NMOS tube is connected to the output end of the charge discharge module and the output end of the charge pump, the floating ground detection module is connected to the charge discharge module and the charge pump control connection, one end of the control pin is connected to the input end of the floating ground detection module and the GND pin in the chip, and the other end is connected to the GPIO pin of an external single-chip computer. The beneficial effects of the present invention are: it can replace the PMOS tube as a switch chip, has low cost, good on-impedance, and has intelligent functions such as current detection and voltage clamping compared to traditional PMOS tubes.

Description

Technical Field

[0001] The present invention relates to the field of circuit technology, and in particular to a switch chip capable of replacing a PMOS tube. Background Art

[0002] MOS tube is a metal-oxide-semiconductor field effect transistor, or metal-insulator-semiconductor. The source and drain of MOS tube can be swapped, and they are both N-type regions formed in P-type backgate. In most cases, these two regions are the same, and even if the two ends are swapped, it will not affect the performance of the device. Such devices are considered symmetrical. MOS transistors are divided into P-type MOS tubes and N-type MOS tubes. An integrated circuit composed of MOS tubes is called a MOS integrated circuit, a circuit composed of NMOS is an NMOS integrated circuit, a circuit composed of PMOS tubes is a PMOS integrated circuit, and a complementary MOS circuit composed of NMOS and PMOS tubes is a CMOS circuit. PMOS tube refers to a MOS tube with an n-type substrate and a p-channel, which transports current by the flow of holes. The full name of NMOS in English is N-Metal-Oxide-Semiconductor. It means N-type metal-oxide-semiconductor, and transistors with this structure are called NMOS transistors.

[0003] As a key switch function module in many systems, PMOS discrete devices can be used in complementary working environments with NMOS due to their voltage conduction characteristics. However, with the same small area (approximately considered as cost), since the mobility of electrons is more than twice the mobility of holes, PMOS needs to pay more than twice the area cost to achieve the same on-resistance performance of NMOS switches. In addition, the conduction characteristics of PMOS will change with the voltage changes caused by the load and the source and drain, resulting in lower on-resistance than expected in many cases, so the performance will also be greatly affected.

[0004] In order to reduce the on-resistance (Rdson) at a low cost, many switches use NMOS as the main switching element. There is a similar type of NMOS driver called a high-side switch. However, if the high-side switch is directly applied to the PMOS scenario, the high-side switch often requires an independent power supply, which is unacceptable in many scenarios and the cost will be too high. Therefore, the designed system can only tolerate the negative impact of PMOS for simplicity and stability and it is difficult to have a better solution. Therefore, people currently hope to have a low-cost PMOS switch, digital level signal control, a system that is not sensitive to power supply, no need for additional power supply, and the use method is exactly the same as PMOS, with lower on-resistance and stable switching characteristics. This is an urgent problem that needs to be solved for people. Summary of the invention

[0005] In order to solve the problems in the prior art, the present invention provides a switch chip that can replace the PMOS tube. By introducing the ground floating drive technology, the GND pin inside the switch chip is hidden, and the switch chip that can replace the PMOS tube is simulated with the NMOS design. It can not only realize the function of the normal switch working scenario of the PMOS, but also achieve the same PMOS on-resistance performance parameters on the market with less than half the MOS area cost, but also has relatively excellent on-resistance and relatively stable load driving capability, does not require additional pins for separate power supply, is fully compatible with the logic control of the PMOS, makes up for the core shortcomings of the PMOS switch scenario, can add more detection and protection functions, and solves the problems of high on-resistance and large occupied area of ​​the PMOS switch in the prior art.

[0006] The present invention provides a switch chip capable of replacing a PMOS tube, comprising an internal control circuit and external pins of the chip, wherein the external pins of the chip include an input pin, an output pin and a control pin, wherein the input pin can be equivalent to replacing the source of the PMOS tube, the output pin can be equivalent to replacing the drain of the PMOS tube, and the control pin can be equivalent to replacing the gate of the PMOS tube. The internal control circuit of the chip comprises an NMOS tube, an internal GND pin of the chip, a floating ground detection module, a charge pump and a charge discharge module, wherein the drain of the NMOS tube is connected to the input pin, and the source of the NMOS tube is connected to the output pin. The floating ground detection module is connected to the charge discharge module and the charge pump control connection, one end of the control pin is connected to the input end of the floating ground detection module and the GND pin in the chip, and the other end of the control pin can be connected to the GPIO pin of the external single-chip microcomputer. The floating ground detection module can detect the control signal of the control pin input by the GPIO pin of the external single-chip microcomputer and control the on-off of the switch between the input pin and the output pin through the gate of the NMOS tube.

[0007] The present invention is further improved. When the control pin receives a high-level signal input from the GPIO pin of the external single-chip microcomputer, the GND pin in the chip floats or is at a high level, and the floating ground detection module controls the charge discharge module to operate transiently, quickly discharges the charge to turn off the NMOS tube, the gate of the NMOS tube is at a low level, and the switch between the input pin and the output pin is disconnected; when the control pin receives a ground signal input from the GPIO pin of the external single-chip microcomputer, the GND pin in the chip is grounded, the floating ground detection module controls the charge pump to turn on, the gate of the NMOS tube is at a high level, and the switch between the input pin and the output pin is connected.

[0008] The present invention is further improved, the control circuit in the chip also includes a reference current module and an oscillator, the reference current module is connected to the oscillator, the source of the NMOS tube, and the input pin for power supply, the oscillator module can control the charge pump to provide a driving voltage for the gate of the NMOS tube, and the driving voltage is greater than a certain proportion of the output voltage VDD of the reference current module.

[0009] The present invention is further improved, the control circuit in the chip also includes an inductor clamping module, and the inductor clamping module can prevent the inductor externally connected to the output pin from pulling down the voltage of the output pin and causing breakdown between the source and the drain of the NMOS tube.

[0010] The present invention is further improved in that the control circuit in the chip further includes a leakage protection module, and the leakage protection module can prevent the chip substrate from generating leakage behavior when the GND pin in the chip is floating.

[0011] The present invention is further improved in that the NMOS tube is arranged in the chip control circuit in an integrated form or a sealed form.

[0012] The present invention is further improved, the external chip pin also includes a current detection pin IS, the internal chip control circuit also includes a current detection module, the input end of the current detection module is connected to the source of the NMOS tube, and the output end of the current detection module is connected to the current detection pin IS.

[0013] Compared with the prior art, the beneficial effects of the present invention are as follows: providing a switch chip capable of replacing a PMOS tube, hiding the GND pin inside the switch chip by introducing a ground floating drive technology, simulating a switch chip capable of replacing a PMOS tube, and therefore, compared with other similar high-side switch solutions on the market, no additional power supply is required, the logic control is fully compatible with PMOS, and there is almost no need to modify the already designed system, and in the absence of an additional power supply, NMOS is used to compensate for the on-resistance of PMOS, achieving the same on-resistance performance parameters of PMOS on the market but requiring less than half the area cost of MOS, and at the same time, inductive clamping protection under inductive loads can be provided to prevent the on-resistance of MOS The possibility of burning MOS is very easy when carrying inductive loads. It can replace PMOS+clamping protection circuit in some inductive applications. The expanded current detection module can monitor the current of the load. In some specific occasions, it can replace the design of PMOS+ammeter. More importantly, its conduction performance is no longer dependent on the external power supply system, load size, etc. like the traditional PMOS switch. As long as it is turned on, it can achieve lower conduction impedance, and can almost achieve consistency in multiple application scenarios, avoiding the uncertainty caused by changes in threshold voltage with process, operating voltage and temperature. Compared with traditional PMOS tubes, it has intelligent functions such as current detection and voltage clamping, which solves the problems of high conduction impedance and large occupied area of ​​PMOS switches in the prior art. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the solutions in the present invention or the prior art, a brief introduction is given below to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0015] Figure 1 This is a principle block diagram of a switch chip capable of replacing a PMOS tube according to the present invention;

[0016] Figure 2 A schematic diagram of a switch chip equivalent to a PMOS tube that can replace a PMOS tube according to the present invention;

[0017] Figure 3 This is a principle block diagram of a switch chip capable of replacing a PMOS tube according to the present invention;

[0018] Figure 4 The schematic diagram is a principle block diagram of a switch chip capable of replacing a PMOS tube according to the present invention. DETAILED DESCRIPTION

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which the present invention belongs; the terms used in the specification of the application herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention; the terms "including" and "having" and any variations thereof in the specification and claims of the present invention and the above-mentioned drawings are intended to cover non-exclusive inclusions. The terms "first", "second", etc. in the specification and claims of the present invention or the above-mentioned drawings are used to distinguish different objects, not to describe a specific order.

[0020] Reference to "embodiments" herein means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present invention. The appearance of the phrase in various places in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0021] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings.

[0022] like Figure 1-Figure 4As shown, the present invention provides a switch chip capable of replacing a PMOS tube, comprising an in-chip control circuit and an off-chip pin, wherein the off-chip pin comprises an input pin, an output pin and a control pin, wherein the input pin can equivalently replace the source of the PMOS tube, the output pin can equivalently replace the drain of the PMOS tube, and the control pin can equivalently replace the gate of the PMOS tube. The in-chip control circuit comprises an NMOS tube, an in-chip GND pin, a floating ground detection module, a charge pump and a charge discharge module, wherein the drain of the NMOS tube is connected to the input pin, the source of the NMOS tube is connected to the output pin, the gate of the NMOS tube is connected to the output end of the charge discharge module and the output end of the charge pump, the floating ground detection module is connected to the charge discharge module and the charge pump control connection, one end of the control pin is connected to the input end of the floating ground detection module and the in-chip GND pin, and the other end of the control pin can be connected to the GPIO pin of an external single-chip computer. In this embodiment, the floating ground detection module can detect the control signal of the control pin input by the GPIO pin of the external single-chip microcomputer and control the on-off of the switch between the input pin and the output pin through the gate of the NMOS tube. When the control pin receives a high-level signal input by the GPIO pin of the external single-chip microcomputer, the GND pin in the chip floats or is at a high level, and the floating ground detection module controls the charge discharge module to operate transiently, quickly discharges the charge to turn off the NMOS tube, and the gate of the NMOS tube is at a low level, and the switch between the input pin and the output pin is disconnected; when the control pin receives a ground signal input by the GPIO pin of the external single-chip microcomputer, the GND pin in the chip is grounded, the floating ground detection module controls the charge pump block to turn on, the gate of the NMOS tube is at a high level, and the switch between the input pin and the output pin is connected.

[0023] like Figure 1-Figure 4As shown, the control circuit in the chip also includes a reference current module, an oscillator and a charge pump. The reference current module is connected to the oscillator, the source of the NMOS tube, and the input pin for power supply. The oscillator module can control the charge pump to provide a driving voltage for the gate of the NMOS tube, and the driving voltage is greater than a certain proportion of the output voltage VDD of the reference current module; the control circuit in the chip also includes an inductor clamping module, which can prevent the inductor externally connected to the output pin from pulling down the voltage of the output pin and causing breakdown between the source and the drain of the NMOS tube; the control circuit in the chip also includes a leakage protection module, which can prevent the chip substrate from leaking when the GND pin in the chip is floating; the NMOS tube is arranged in the chip control circuit in an integrated form or a sealed form; the pin outside the chip also includes a current detection pin IS, and the control circuit in the chip also includes a current detection module, the input end of the current detection module is connected to the source of the NMOS tube, and the output end of the current detection module is connected to the current detection pin IS. In this embodiment, an NMOS tube + charge pump is used to disguise as a switch chip that can replace the PMOS tube, and the ground of the entire switch chip is used as the start-up switch. The application scenario is exactly the same as the PMOS switch application scenario. The switch chip is only designed with three PIN pins, namely PMOS Source (source), PMOS Gate (gate), and PMOSDrain (drain). When the PMOS Gate is at a low level, due to the high level connection of the PMOS Source, a current path to the PMOS Gate pin will be formed internally to enable the switch chip to work normally. The PMOS Gate pin voltage can generally be pulled up to almost twice the output voltage VDD of the reference current module due to the charge pump, as the start-up voltage of the NMOS, turning on the built-in or co-packaged NMOS tube to form an electronic-based conduction impedance channel. At this time, the PMOS Source and PMOS Drain will be turned on (similar to PMOS) to form a low-resistance channel, completing the chip's startup function; when the PMOS Gate is high or floating, the current previously formed inside to the PMOS Gate pin will stop flowing due to the high-level connection of the PMOS Source, and the floating detection module circuit of the chip will be triggered to turn off the PMOS Gate voltage to turn off the chip. The overall circuit diagram is as follows Figure 1 As shown, Figure 3 yes Figure 1 Another form of sealed NMOS, the working principle is similar to Figure 1 The core of the whole circuit is to use floating drive design for the GND pin inside the chip, which is actually equivalent to providing a low-level path for the external control signal. From the outside, it is like driving a PMOS tube (such as Figure 2 The entire switch chip is composed of Figure 1 and Figure 3 The display includes reference current module, inductor clamp module, floating detection module, leakage protection module, oscillator, charge pump, charge discharge module, NMOS tube (sealed or integrated), etc. The reference current module can provide the entire switch chip system with a reference current that changes very little with temperature, and provide a stable working state for the entire switch chip system; the inductor clamp module provides the possibility of driving inductor protection for the entire switch chip system. When driving the inductive load, the OUT port of the MOS tube will be pulled down due to the external inductor. At this time, if the inductance is large, it will directly exceed the breakdown voltage of the source and drain. Therefore, it is almost impossible for a pure PMOS tube to drive a high inductive load. If there is an inductor clamp, it is possible to replace the PMOS+ protection circuit; the floating detection module detects the signal received by the GND pin in the chip (that is, PMOS Gate). When it is higher than a certain value (about to become a high level or has floated), it triggers the charge discharge module to quickly turn off the MOS tube drive, and at the same time turn off the oscillator and charge pump. Otherwise, if there is no such function, the fast opening and closing design cannot be achieved; the leakage protection module is to prevent the GND pin in the chip (PMOS Gate) from being damaged. When the Gate is floating or at a high level, the substrate of the switch chip will leak electricity, and this module is needed to prevent the substrate from leaking electricity. The oscillator generates the system clock and the charge pump drive signal, and the charge pump raises the gate voltage of the NMOS tube to a VDD voltage not exceeding a certain multiple (the output voltage of the reference current module). Therefore, it can drive the subsequent NMOS tubes so that they are not restricted by the power supply working conditions and can operate at a lower on-impedance. NMOS tubes can be designed in integrated form or sealed form, which is actually related to the application scenario. There is no essential difference in the working of the two. Figure 1 and Figure 3 On this basis, a current detection module can also be designed. The output current source flows out through the current detection pin IS, and the detection current flowing through the NMOS tube can be output without affecting the normal function of the replaced PMOS.

[0024] As can be seen from the above, the present invention provides a switch chip that can replace the PMOS tube. By introducing the ground floating drive technology, the GND pin inside the switch chip is hidden, and the switch chip that can replace the PMOS tube is simulated. Therefore, compared with other similar high-side switch solutions on the market, no other additional power supply is required, and the logic control is fully compatible with PMOS. There is almost no need to change the already designed system. In the absence of additional power supply, NMOS is used to compensate for the PMOS on-resistance, achieving the same PMOS on-resistance performance parameters on the market but only requiring less than half the MOS area cost. At the same time, inductive clamping protection under inductive load can be provided to prevent MOS from carrying inductive loads. It is very easy to burn out the MOS, and it can replace the PMOS+ clamping protection circuit in some inductive applications. The expanded current detection module can monitor the current of the load, and can replace the PMOS+ ammeter design in some specific occasions. More importantly, its conduction performance is no longer dependent on the external power supply system, load size, etc. like the traditional PMOS switch. As long as it is turned on, it can achieve a lower on-resistance, and can almost achieve consistency in multiple application scenarios, avoiding the uncertainty caused by changes in threshold voltage with process, operating voltage and temperature. Compared with traditional PMOS tubes, it has intelligent functions such as current detection and voltage clamping, which solves the problems of high on-resistance and large occupied area of ​​PMOS switches in the prior art.

[0025] The specific implementation modes described above are preferred implementation modes of the present invention, and are not intended to limit the specific implementation scope of the present invention. The scope of the present invention includes but is not limited to the specific implementation modes, and all equivalent changes made according to the present invention are within the protection scope of the present invention.

Claims

1. A switch chip capable of replacing a PMOS tube, characterized in that: The invention comprises an on-chip control circuit and off-chip pins, wherein the off-chip pins comprise an input pin, an output pin and a control pin, wherein the input pin can be equivalent to a source of a PMOS tube, the output pin can be equivalent to a drain of a PMOS tube, and the control pin can be equivalent to a gate of a PMOS tube. The on-chip control circuit comprises an NMOS tube, an on-chip GND pin, a floating ground detection module, a charge pump and a charge discharge module, wherein the drain of the NMOS tube is connected to the input pin, the source of the NMOS tube is connected to the output pin, the gate of the NMOS tube is connected to the output end of the charge discharge module and the output end of the charge pump, the floating ground detection module is connected to the charge discharge module and the charge pump control connection, one end of the control pin is connected to the input end of the floating ground detection module and the on-chip GND pin, and the other end of the control pin can be connected to the GPIO of an external single-chip computer. The floating ground detection module is connected to the pins, the floating ground detection module can detect the control signal of the control pin input by the GPIO pin of the external single-chip microcomputer and control the on-off of the switch between the input pin and the output pin through the gate of the NMOS tube. When the control pin receives the high-level signal input by the GPIO pin of the external single-chip microcomputer, the GND pin in the chip floats or is at a high level, and the floating ground detection module controls the charge discharge module to work transiently, discharges the charge quickly to turn off the NMOS tube, the gate of the NMOS tube is at a low level, and the switch between the input pin and the output pin is disconnected; when the control pin receives the grounding signal input by the GPIO pin of the external single-chip microcomputer, the GND pin in the chip is grounded, the floating ground detection module controls the charge pump to start, the gate of the NMOS tube is at a high level, and the switch between the input pin and the output pin is connected.

2. The switch chip capable of replacing a PMOS tube according to claim 1, characterized in that: The control circuit in the chip also includes a reference current module and an oscillator. The reference current module is connected to the oscillator, the source of the NMOS tube, and the input pin for power supply. The oscillator can control the charge pump to provide a driving voltage for the gate of the NMOS tube, and the driving voltage is greater than a certain proportion of the output voltage VDD of the reference current module.

3. The switch chip capable of replacing a PMOS tube according to claim 2, characterized in that: The control circuit in the chip further includes an inductor clamping module, which can prevent the inductor externally connected to the output pin from pulling down the voltage of the output pin and causing breakdown between the source and drain of the NMOS tube.

4. The switch chip capable of replacing a PMOS tube according to claim 3, characterized in that: The control circuit in the chip also includes a leakage protection module, which can prevent the chip substrate from generating leakage behavior when the GND pin in the chip is floating.

5. The switch chip capable of replacing a PMOS tube according to claim 4, characterized in that: The NMOS tube is arranged in the chip control circuit in an integrated form or a packaged form.

6. The switch chip capable of replacing a PMOS tube according to claim 5, characterized in that: The off-chip pins further include a current detection pin IS, and the on-chip control circuit further includes a current detection module, the input end of the current detection module is connected to the source of the NMOS tube, and the output end of the current detection module is connected to the current detection pin IS.

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