Automatic protection circuit

Abstract

This invention discloses an automatic protection circuit, which is included in the driving circuit of a chip. The transistors in the driving circuit are low-voltage transistors, and the maximum value of the output voltage generated by the driving circuit through the output node is greater than the maximum withstand voltage of the low-voltage transistor. The automatic protection circuit includes a first transistor and a protection module. The protection module includes a third transistor and a first protection node. The first transistor is connected to a first power supply and the first protection node. The protection module is connected to the output node and the first protection node through the third transistor, and is used to turn off the third transistor when the output voltage of the output node exceeds the maximum withstand voltage, thereby preventing the output voltage from flowing back to the first transistor. In this automatic protection circuit, the withstand voltages (VGS and VGD) of all transistors are less than the maximum withstand voltage of the low-voltage transistor, while the output voltage of the driving circuit can be higher than the maximum withstand voltage of the low-voltage transistor.

Description

Technical Field

[0001] This invention relates to the field of chip design, and more particularly to an automatic protection circuit. Background Technology

[0002] Novel non-volatile memories such as resistive random access memory (RRAM), magnetic random access memory (MRAM), and phase-change random access memory (PCRAM) typically require higher voltages (above the core logic voltage VDD) for write operations and lower voltages (usually VDD or lower) for read operations. Since low-voltage transistors can break down under high voltage loads, high-voltage transistors are typically used in arrays to drive write operations. However, high-voltage transistors are usually large, significantly increasing chip footprint, and their slow charging and discharging speeds result in slower operation speeds, higher power consumption, and negatively impact chip performance.

[0003] To enable the driving of low-voltage transistors, a protection mechanism is needed to prevent overvoltage conditions in the low-voltage transistors. Therefore, this specification provides an automatic protection circuit. Summary of the Invention

[0004] The present invention provides an automatic protection circuit to at least partially solve the above-mentioned problems existing in the prior art.

[0005] The present invention adopts the following technical solution:

[0006] This invention provides an automatic protection circuit, which is included in the driving circuit of a chip. The transistor in the driving circuit is a low-voltage transistor, and the maximum value of the output voltage generated by the driving circuit through the output node is greater than the maximum withstand voltage of the low-voltage transistor. The automatic protection circuit includes a first transistor and a protection module, and the protection module includes a third transistor and a first protection node, wherein:

[0007] The first transistor is connected to the first power supply and the first protection node;

[0008] The protection module connects the output node and the first protection node via the third transistor. When the output voltage of the output node exceeds the maximum withstand voltage, the third transistor is turned off to prevent the output voltage from flowing back into the first transistor.

[0009] Optionally, the protection module further includes a second transistor and a second protection node, the second protection node being connected to the gate of the third transistor, and the gate of the second transistor being connected to a second power supply;

[0010] The second transistor is located between the output node and the second protection node.

[0011] Optionally, when the output voltage of the output node exceeds the maximum withstand voltage, the second transistor is turned on, increasing the voltage of the second protection node and causing the third transistor to turn off.

[0012] Optionally, the protection module further includes a fourth transistor, a fifth transistor, and a third protection node, wherein the fourth transistor and the fifth transistor are connected in series;

[0013] The fourth transistor is connected to the third transistor via the second protection node;

[0014] The fifth transistor is grounded;

[0015] The third protection node is located between the fourth transistor and the fifth transistor.

[0016] Optionally, the gate of the fourth transistor is connected to a third power supply;

[0017] When the output voltage of the output node exceeds the maximum withstand voltage, the second transistor turns on, increasing the voltage of the second protection node. The voltage of the second protection node is then transmitted to the third protection node through the fourth transistor, causing the fourth transistor to turn off to prevent the fifth transistor from overvoltage.

[0018] Optionally, the first transistor and the fifth transistor are connected to a control signal.

[0019] Optionally, the driving circuit has a low-voltage mode and a high-voltage mode, wherein the output voltage generated in the low-voltage mode does not exceed the maximum withstand voltage value, and the output voltage generated in the high-voltage mode exceeds the maximum withstand voltage value.

[0020] Optionally, when the control signal controls the drive circuit to operate in the low-voltage mode, the first transistor, the second transistor, and the fifth transistor are turned off, while the third transistor and the fourth transistor are turned on.

[0021] Optionally, when the control signal controls the drive circuit to operate in the high-voltage mode, the second transistor is turned on, causing the third transistor and the fourth transistor to be turned off.

[0022] Optionally, when the control signal controls the drive circuit to switch from the low-voltage mode to the high-voltage mode, the second transistor changes from off to on.

[0023] The above-mentioned at least one technical solution adopted in this invention can achieve the following beneficial effects:

[0024] The automatic protection circuit provided by this invention can protect the output voltage of the monitoring output node of the module. When the output voltage exceeds the maximum withstand voltage of the transistor in the automatic protection circuit, the current path between the output node and the first protection node is cut off by controlling the third transistor to turn off, thereby preventing the high voltage backflow of the first transistor. Attached Figure Description

[0025] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and are used to explain the invention, but do not constitute an undue limitation of the invention. In the drawings:

[0026] Figure 1 A schematic diagram of an automatic protection circuit structure provided in an embodiment of the present invention;

[0027] Figure 2 A schematic diagram of an automatic protection circuit structure provided in an embodiment of the present invention;

[0028] Figure 3 A voltage variation diagram is provided for an embodiment of the present invention. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below in conjunction with specific embodiments and corresponding drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0030] To address the driving problem of low-voltage transistors, this invention designs an automatic protection circuit internal to the chip driver circuit. This circuit protects the low-voltage transistors from backflow when the driver circuit generates a higher output voltage, preventing the low-voltage transistors from being damaged. This automatic protection circuit provides protection within the low-voltage transistor driver circuit, allowing the driver circuit to be designed solely using low-voltage transistors, reducing chip footprint, increasing read / write speed, and lowering power consumption.

[0031] The technical solutions provided by the various embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Figure 1 This is a schematic diagram of an automatic protection circuit structure provided in an embodiment of the present invention. Figure 1 As shown, the automatic protection circuit includes a first transistor M1 and a protection module, and the protection module includes a third transistor M3 and a first protection node PROT.

[0033] The automatic protection circuit is included in the chip's driver circuit, which uses low-voltage transistors; that is, all transistors in the driver circuit are low-voltage transistors. The driver circuit generates an output voltage through the output node to drive read and write operations. The driver circuit needs to generate a higher voltage for writing operations and a lower voltage for reading operations. Generally, the voltage used for writing operations is the maximum value of the output voltage generated by the driver circuit. Therefore, the output voltage generated by the driver circuit during operation is between 0 and its maximum value.

[0034] The maximum output voltage generated by this drive circuit is greater than the maximum withstand voltage of the low-voltage transistor. Therefore, if the output voltage exceeds the maximum withstand voltage of the low-voltage transistor, current will flow back into the low-voltage transistor, causing it to break down.

[0035] like Figure 1 As shown, in the automatic protection circuit of this invention, the first transistor M1 is connected to the first power supply VDD and the first protection node PROT. The protection module is connected to the output node and the first protection node PROT via the third transistor M3. This protection module is used when the output voltage VDD of the output node is... AGG When the voltage exceeds the maximum withstand voltage of the low-voltage transistor, the third transistor M3 is turned off. That is, the current path between the output node and the first protection node PROT is cut off, preventing the output voltage V from exceeding the withstand voltage. AGG Backflow into the first transistor caused it to break down.

[0036] In the automatic protection circuit of the present invention, the voltage withstand values ​​(VGS and VGD) of all transistors in the circuit are less than the maximum withstand voltage of the low-voltage transistor, while the output voltage of the drive circuit can be higher than the maximum withstand voltage of the low-voltage transistor.

[0037] Figure 2 This is a schematic diagram of an automatic protection circuit structure provided by an embodiment of the present invention. The following is in conjunction with... Figure 2 The automatic protection circuit provided by the present invention will be described in detail.

[0038] like Figure 2 As shown, in some embodiments, the protection module further includes a second transistor M2 and a second protection node GPROT, the gate of which is connected to the gate of a third transistor M3, and the gate of the second transistor M2 is connected to a second power supply VDD. The second transistor M2 is located between the output node and the second protection node GPROT.

[0039] In this embodiment, the gate of the second transistor M2 is connected to the second power supply VDD, the source is connected to the second protection node GPROT, and the drain is connected to the output node. The gate of the third transistor M3 is connected to the second protection node GPROT, the source is connected to the first protection node PROT, and the drain is connected to the output node.

[0040] When the output voltage does not exceed the maximum withstand voltage, the second transistor M2 is in the off state.

[0041] When the output voltage exceeds the maximum withstand voltage, the second transistor M2 turns on, connecting the current path between the output node and the second protection node GPROT, thereby transferring the output voltage to the second protection node GPROT, increasing the voltage of the second protection node GPROT, and turning off the third transistor M3 to prevent the large output voltage from flowing back into the first transistor M1.

[0042] For example, when the output voltage reaches VDD+Vth (Vth is the threshold voltage of the low-voltage transistor), the gate-source voltage VGS of the second transistor M2 reaches Vth, and the second transistor M2 is turned on.

[0043] In some embodiments, the protection module further includes a fourth transistor M4, a fifth transistor M5, and a third protection node SPROT. For example... Figure 2 As shown, the fourth transistor M4 and the fifth transistor M5 are connected in series. The fourth transistor M4 is connected to the third transistor M3 through the second protection node GPROT. The fifth transistor M5 is grounded. The third protection node SPROT is located between the fourth transistor M4 and the fifth transistor M5.

[0044] In this embodiment, the drain of the fourth transistor M4 is connected to the second protection node GPROT, and the source of the fourth transistor M4 is connected to the drain of the fifth transistor M5. When both the fourth transistor M4 and the fifth transistor M5 are turned on, the second protection node GPROT is at a low level.

[0045] In this automatic protection circuit, the current path of the fourth transistor M4 is from the second protection node GPROT to the third protection node SPROT, and then through the fifth transistor M5, which transfers the voltage of the second protection node GPROT to the third protection node SPROT. However, if the voltage of the third protection node SPROT is too high, the gate-source voltage VGS of the fifth transistor M5 will be too high, causing the fifth transistor M5 to break down.

[0046] In some embodiments, the gate of the fourth transistor M4 is connected to the third power supply VDD, the source is connected to the fifth transistor M5 through the third protection node SPROT, and the drain is connected to the second protection node GPROT. When the output voltage of the output node exceeds the maximum withstand value, the second transistor M2 is turned on, connecting the current path between the output node and the second protection node GPROT, thereby transferring the output voltage to the second protection node GPROT, increasing the voltage of the second protection node GPROT. This voltage of the second protection node GPROT is then transferred to the third protection node SPROT through the fourth transistor M4, causing the fourth transistor M4 to be turned off to prevent the fifth transistor M5 from overvoltage.

[0047] When the voltage of the second protection node GPROT is transferred to the third protection node SPROT through the fourth transistor M4, the voltage V of the third protection node SPROT... SPROT Increase, when V SPROT When the voltage rises to VDD-Vth (Vth is the threshold voltage of the low-voltage transistor), the gate-source voltage VGS of the fourth transistor M4 reaches VDD-Vth, and the fourth transistor M4 is turned off, thereby limiting the maximum voltage of the third protection node SPROT to VDD-Vth and protecting the fifth transistor M5 from overvoltage.

[0048] In some embodiments, the driving circuit is connected to a control signal via a first transistor M1 and a fifth transistor M5 to control the magnitude of the output voltage generated by the driving circuit, thereby enabling the driving circuit to generate a high voltage suitable for writing and a low voltage suitable for reading. In some embodiments, the first transistor M1 is connected to a first control signal V. CTRL The fifth transistor M5 is connected to the second control signal V. CTRL2 .

[0049] In some embodiments, the driving circuit has a low-voltage mode and a high-voltage mode. The output voltage generated in the low-voltage mode does not exceed the maximum withstand voltage of the low-voltage transistor and is suitable for driving read operations. The output voltage generated in the high-voltage mode exceeds the maximum withstand voltage of the low-voltage transistor and is suitable for driving write operations.

[0050] In some embodiments, under high voltage mode, the first drive signal and the second drive signal are at high level, and under low voltage mode, the first drive signal and the second drive signal are at low level.

[0051] In low-voltage mode, the output voltage does not exceed the maximum withstand voltage of the low-voltage transistor, and there is no risk of overvoltage for any transistor in the drive circuit; the automatic protection circuit is in standby mode. In high-voltage mode, the output voltage exceeds the maximum withstand voltage of the low-voltage transistor, and there is a risk of overvoltage for any transistor in the drive circuit; the automatic protection circuit then activates.

[0052] In some embodiments, when the control signal controls the drive circuit to operate in the high-voltage mode, the second transistor M2 is turned on, causing the third transistor M3 and the fourth transistor M4 to be turned off.

[0053] The gate of the fifth transistor M5 is connected to the second control signal, its source is grounded, and its drain is connected to the fourth transistor M4 through the third protection node SPROT. In high-voltage mode, the second control signal is high, and the fifth transistor M5 is turned on. The gate of the fourth transistor M4 is connected to the third power supply VDD, its source is connected to the fifth transistor M5 through the third protection node SPROT, and its drain is connected to the second protection node GPROT.

[0054] In high-voltage mode, the output voltage is greater than the maximum withstand voltage of the low-voltage transistor, which turns on the second transistor M2 and turns off the third transistor M3 to protect the first transistor M1 from being damaged. It also turns off the fourth transistor M4 to protect the fifth transistor M5 from being damaged.

[0055] In some embodiments, when the control signal controls the drive circuit to switch from low-voltage mode to high-voltage mode, the second transistor M2 changes from off to on.

[0056] During the transient mode switching, as the output voltage changes from low to high, the gate-source voltage VGS of the second transistor M2 gradually approaches the threshold voltage until it turns on. For example, during the transition from the low-voltage mode (VDD) to the high-voltage mode (2VDD), when the output voltage rises to VDD+Vth, the gate-source voltage of the second transistor M2 reaches the threshold voltage. As the output voltage continues to rise, the gate-source voltage of the second transistor M2 exceeds the threshold voltage, causing it to turn on from off. After the second transistor M2 turns on, the output voltage is transmitted to the second protection node GPROT, causing the gate-source voltage VGS of the third transistor M3 to... GS That is, the voltage V of the second protection node GPROT. GPROT and the voltage V of the first protection node PROT PROT The difference (V) GS =V GPROT -V PROT ) then increases (negative values ​​decrease). When V GPROT Reaching V PROT When -Vth, the third transistor M3 is turned off, cutting off the current path from the output node to the first protection node PROT, preventing high voltage from flowing back into the first transistor M1.

[0057] At the same time, when the voltage V of the second protection node GPROT GPROT During the rise, the voltage V of the third protection node SPROT SPROT As it rises, when the voltage V of the third protection node SPROT increases... SPROTWhen VDD-Vth is reached, the fourth transistor M4 is turned off, thus preventing V from being turned off. SPROT Further rise, making V SPROT It is clamped at VDD-Vth. This protects the fifth transistor M5 because the gate-source voltage VDS of the fifth transistor M5 is V... SPROT ≤VDD-Vth, within the safe range, there is no risk of overvoltage.

[0058] Figure 3 This is a voltage change diagram provided in the embodiments of this specification, such as... Figure 3 As shown, when the drive circuit is in low-voltage mode, the voltage rises from 0 to VDD. At this time, the second transistor M2 is cut off, and the voltage of the second protection node GPROT is 0. When the drive circuit is in high-voltage mode, the output voltage V... AGG The transient rise from 0 to 2VDD, at the output voltage V AGG When the voltage reaches VDD+Vth, the second transistor M2 will turn on, thereby increasing the output voltage V. AGG Passed to the second protection node, GPROT. From Figure 3 It can be seen that, under high voltage mode, the voltage V of the second protection node GPROT is... GPROT and output voltage V AGG Synchronous changes.

[0059] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0060] The various embodiments in this specification are described in a progressive manner. Similar or identical parts between embodiments can be referred to interchangeably. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0061] The above description is merely an embodiment of this specification and is not intended to limit the scope of this specification. Various modifications and variations can be made to this specification by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this specification should be included within the scope of the claims of this invention.

Claims

1. An automatic protection circuit, characterized by The automatic protection circuit is included in the chip's driving circuit. The transistors in the driving circuit are low-voltage transistors. The maximum value of the output voltage generated by the driving circuit through the output node is greater than the maximum withstand voltage of the low-voltage transistor. The automatic protection circuit includes a first transistor and a protection module, wherein the protection module includes a third transistor and a first protection node, wherein: The first transistor is connected to the first power supply and the first protection node; The protection module connects the output node and the first protection node through the third transistor, and is used to turn off the third transistor when the output voltage of the output node exceeds the maximum withstand voltage value, so as to prevent the output voltage from flowing back to the first transistor. The protection module further includes a fourth transistor, a fifth transistor, and a third protection node, wherein the fourth transistor and the fifth transistor are connected in series; The fourth transistor is connected to the third transistor via the second protection node; The fifth transistor is grounded; The third protection node is located between the fourth transistor and the fifth transistor; The protection module further includes a second transistor and a second protection node, the second protection node being connected to the gate of the third transistor, and the gate of the second transistor being connected to a second power supply. The second transistor is located between the output node and the second protection node.

2. The automatic protection circuit as described in claim 1, characterized in that, When the output voltage of the output node exceeds the maximum withstand voltage, the second transistor turns on, increasing the voltage of the second protection node and causing the third transistor to turn off.

3. The automatic protection circuit as described in claim 1, characterized in that, The gate of the fourth transistor is connected to the third power supply; When the output voltage of the output node exceeds the maximum withstand voltage, the second transistor turns on, increasing the voltage of the second protection node. The voltage of the second protection node is then transmitted to the third protection node through the fourth transistor, causing the fourth transistor to turn off to prevent the fifth transistor from overvoltage.

4. The automatic protection circuit as described in claim 3, characterized in that, The first transistor and the fifth transistor are connected to the control signal.

5. The automatic protection circuit as described in claim 4, characterized in that, The driving circuit has a low-voltage mode and a high-voltage mode. The output voltage generated in the low-voltage mode does not exceed the maximum withstand voltage value, and the output voltage generated in the high-voltage mode exceeds the maximum withstand voltage value.

6. The automatic protection circuit as described in claim 5, characterized in that, When the control signal controls the drive circuit to operate in the low-voltage mode, the first transistor, the second transistor, and the fifth transistor of the automatic protection circuit are turned off, while the third transistor and the fourth transistor are turned on.

7. The automatic protection circuit as described in claim 5, characterized in that, When the control signal controls the drive circuit to operate in the high-voltage mode, the second transistor is turned on, causing the third and fourth transistors to be turned off.

8. The automatic protection circuit as described in claim 5, characterized in that, When the control signal controls the drive circuit to switch from the low-voltage mode to the high-voltage mode, the second transistor changes from off to on.

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