CN109887912B - Electrostatic protection circuit for application of bipolar integrated circuit of cold backup system - Google Patents
Electrostatic protection circuit for application of bipolar integrated circuit of cold backup system Download PDFInfo
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- CN109887912B CN109887912B CN201910168453.8A CN201910168453A CN109887912B CN 109887912 B CN109887912 B CN 109887912B CN 201910168453 A CN201910168453 A CN 201910168453A CN 109887912 B CN109887912 B CN 109887912B
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Abstract
The invention discloses an electrostatic protection circuit for application of a bipolar integrated circuit of a cold backup system, which overcomes the defect that the traditional diode electrostatic protection structure cannot meet the application requirement of cold backup because a low-resistance channel exists from an input/output port to a positive power supply. The two port positive power supplies do not have a low-resistance path, so that the chip can meet the requirements of cold backup application. Meanwhile, the bipolar transistor Q1 and the bipolar transistor Q2 accelerate the discharge of electrostatic energy, and the antistatic capability of the chip can be effectively improved.
Description
Technical Field
The invention belongs to the field of integrated circuit design, and particularly relates to an electrostatic protection circuit for application of a bipolar integrated circuit of a cold backup system.
Background
The bipolar electrostatic protection circuit is an indispensable component module in a high-reliability bipolar analog integrated circuit chip and is used for protecting functional performance parameters of the chip from being influenced after a chip pin is subjected to certain electrostatic discharge stress. At present, a cold backup design method with high reliability, long service life, low energy consumption and convenient switching is generally used in the field of high-reliability system design such as aerospace and the like. The cold backup application is a key problem which must be solved by aerospace component development and application. Especially, the realization of the cold backup function of the integrated circuit for the interface is an important content of the localization work of the components. The i/o port of the device with the cold backup function must be in a high impedance state to the positive power supply to avoid leakage from the i/o port to the positive power supply. Therefore, the electrostatic protection structure of the chip applied in the cold backup system needs to be designed such that the input/output port is in a high impedance state to the positive power supply. However, the use of the conventional bipolar esd protection circuit as shown in fig. 1 does not allow the chip to meet the requirements of the cold backup design.
As shown in fig. 1, it is an electrostatic protection circuit between any two input/output ports of the chip and the positive and negative power supplies. The diode D1 and the diode D2 form an electrostatic protection circuit of the PORT1, the diode D3 and the diode D4 form an electrostatic protection circuit of the PORT2, and VS + is a positive power supply voltage and VS-is a negative power supply voltage.
In the electrostatic protection circuit of PORT1, the negative terminal of diode D1 is connected to positive power source VS +, the negative terminal of diode D1 is connected to PORT1 and the negative terminal of diode D2, and the positive terminal of diode D2 is connected to the negative power source voltage.
In the electrostatic protection circuit of PORT2, the negative terminal of diode D3 is connected to positive power source VS +, the negative terminal of diode D3 is connected to PORT2 and the negative terminal of diode D4, and the positive terminal of diode D4 is connected to the negative power source voltage.
Referring to fig. 1, the operation of the esd protection circuit will be described with respect to the esd paths between PORT1 and the PORTs.
When PORT1 is at high potential and the rest PORTs are at low potential, electrostatic energy can be discharged by forward conduction between the PORT1 and VS + through diode D1, electrostatic energy can be discharged by reverse Zener breakdown of diode D2 between VS, and electrostatic energy can be discharged by two paths between PORT2 (1. electrostatic energy is discharged by forward conduction through diode D1 while reverse Zener breakdown of diode D3; 2. electrostatic energy is discharged by reverse Zener breakdown of diode D2 while forward conduction through diode D4).
When PORT1 is at low potential and the rest PORTs are at high potential, electrostatic energy can be discharged between PORT and VS + through reverse Zener breakdown of diode D1, electrostatic energy can be discharged between VS and VS-through forward conduction of diode D2, and electrostatic energy discharge can be performed between PORT2 through two paths (1. electrostatic energy is discharged through forward conduction of diode D3 and reverse Zener breakdown of diode D1; 2. electrostatic energy is discharged through reverse Zener breakdown of diode D4 and forward conduction of diode D2).
However, the electrostatic protection circuit shown in fig. 1 has the following disadvantages:
1. because the forward diode structure is between the input/output PORTs (PORT1, PORT2) and the positive power source VS +, the input/output PORTs cannot form a high impedance state to the positive power source, and thus cannot meet the PORT characteristic requirements of the cold backup system.
2. The electrostatic energy is completely absorbed by the Zener breakdown of the diode, and if the anti-static capacity is improved, the layout area of the diode is increased sharply.
From the above analysis, in order to meet the port characteristic requirements of the cold backup chip, a general electrostatic protection circuit needs to be invented to ensure that a high resistance state is formed from the input/output port to the positive power supply, and meanwhile, the layout area is not sharply increased along with the enhancement of the electrostatic capacity.
Disclosure of Invention
The invention aims to overcome the defects and provide an electrostatic protection circuit for the application of a bipolar integrated circuit of a cold backup system, so that the problem of realizing the electrostatic protection function of a chip meeting the cold backup requirement on different process platforms by using a smaller layout area is solved.
In order to achieve the purpose, the electrostatic protection circuit comprises a positive power supply VS + and a negative power supply VS-, a diode D3 is arranged between the positive power supply VS + and the negative power supply VS-, the negative end of a diode D3 is connected with the positive power supply VS +, the positive end of a diode D3 is connected with the negative power supply VS-, the negative power supply VS-is connected with a PORT PORT1 and a PORT PORT2, and electrostatic protection circuits are arranged between a PORT PORT1 and a PORT PORT2 and the negative power supply VS-;
the electrostatic protection circuit between the PORT PORT1 and the negative power supply VS-comprises a diode D1, a resistor R1 and a bipolar transistor Q1, wherein the negative terminal of the diode D1 is connected with the PORT PORT1, the positive terminal of the diode D1 is connected with the base of the bipolar transistor Q1 and one end of the resistor R1, the negative power supply VS-is connected with the other end of the resistor R1 and the emitter of the bipolar transistor Q1, and the collector of the bipolar transistor Q1 is connected with the PORT PORT 1;
the electrostatic protection circuit between the PORT PORT2 and the negative power supply VS-comprises a diode D2, a resistor R2 and a bipolar transistor Q2, wherein the negative terminal of the diode D2 is connected with the PORT PORT2, the positive terminal of the diode D2 is connected with the base of the bipolar transistor Q2 and one end of the resistor R2, the negative power supply VS-is connected with the other end of the resistor R2 and the emitter of the bipolar transistor Q2, and the collector of the bipolar transistor Q2 is connected with the PORT PORT 2.
The PORT1 and the PORT2 are input/output terminals.
The negative supply VS-is a common node.
Both bipolar transistor Q1 and bipolar transistor Q2 are NPN type.
The diode D1 and the diode D2 are zener breakdown diodes.
Compared with the prior art, the invention overcomes the defect that the traditional diode electrostatic protection structure cannot meet the application requirement of cold backup because a low-resistance channel exists from an input/output port to a positive power supply. The two port positive power supplies do not have a low-resistance path, so that the chip can meet the requirements of cold backup application. Meanwhile, the bipolar transistor Q1 and the bipolar transistor Q2 accelerate the discharge of electrostatic energy, and the antistatic capability of the chip can be effectively improved.
Furthermore, the diode D1 and the diode D2 of the invention are zener breakdown diodes, and the breakdown voltages of the diode D1 and the diode D2 can be adjusted to meet the voltage withstanding requirements of different process platforms, so that the electrostatic protection structure has the portability of the process platforms, and the flexibility and the universality of the electrostatic protection circuit are improved.
Drawings
FIG. 1 is a circuit diagram of a conventional ESD protection circuit with a diode structure;
fig. 2 is a circuit diagram of the present invention.
Detailed Description
The invention is further described below with reference to the accompanying drawings.
Referring to fig. 2, the invention comprises a positive power supply VS + and a negative power supply VS-, a diode D3 is arranged between the positive power supply VS + and the negative power supply VS-, the negative terminal of the diode D3 is connected with the positive power supply VS +, the positive terminal of the diode D3 is connected with the negative power supply VS-, the negative power supply VS-is connected with a PORT1 and a PORT2, and an electrostatic protection circuit is arranged between the PORT1 and a PORT2 and the negative power supply VS-;
the electrostatic protection circuit between the PORT PORT1 and the negative power supply VS-comprises a diode D1, a resistor R1 and a bipolar transistor Q1, wherein the negative terminal of the diode D1 is connected with the PORT PORT1, the positive terminal of the diode D1 is connected with the base of the bipolar transistor Q1 and one end of the resistor R1, the negative power supply VS-is connected with the other end of the resistor R1 and the emitter of the bipolar transistor Q1, and the collector of the bipolar transistor Q1 is connected with the PORT PORT 1;
the electrostatic protection circuit between the PORT PORT2 and the negative power supply VS-comprises a diode D2, a resistor R2 and a bipolar transistor Q2, wherein the negative terminal of the diode D2 is connected with the PORT PORT2, the positive terminal of the diode D2 is connected with the base of the bipolar transistor Q2 and one end of the resistor R2, the negative power supply VS-is connected with the other end of the resistor R2 and the emitter of the bipolar transistor Q2, and the collector of the bipolar transistor Q2 is connected with the PORT PORT 2.
The PORT1 and the PORT2 are input/output terminals, the negative power source VS-is a common node, the bipolar transistor Q1 and the bipolar transistor Q2 are both NPN-type, and the diode D1 and the diode D2 are zener breakdown diodes.
The operation of the esd protection circuit will be described below with respect to the esd paths between the PORT1 and each PORT.
When the PORT PORT1 is at a high potential and the other PORTs are at a low potential, Zener breakdown can be realized between the PORT PORT1 and the negative power supply VS-through the diode D1, the voltage drop of the resistor R1 causes the base and the emitter of the bipolar transistor Q1 to be rapidly opened, the bipolar transistor Q1 starts to work, and electrostatic energy is discharged to the negative power supply VS-PORT through the bipolar transistor Q1 with the amplification function. The diode D1, the resistor R1 and the bipolar transistor Q1 can work to discharge electrostatic energy from the positive power source VS + when the diode D3 is turned on in the forward direction. The electrostatic energy can be discharged from the PORT2 through the diode D1, the resistor R1 and the bipolar transistor Q1, and then the collector-substrate junction of the bipolar transistor Q2 is turned on in the forward direction.
When the PORT PORT1 is at a low voltage level and the remaining PORTs are at a high voltage level, the electrostatic energy can be discharged from the negative power source VS-via the forward conduction of the collector-substrate junction of the bipolar transistor Q1. The zener diode D3 can break down from the positive power source VS +, and the collector-substrate junction of the bipolar transistor Q1 is turned on in the forward direction to discharge the electrostatic energy. The electrostatic energy can be discharged from the PORT2 through the diode D2, the resistor R2 and the bipolar transistor Q2, and then the collector-substrate junction of the bipolar transistor Q1 is turned on in the forward direction.
The invention can provide an effective static electricity discharge path, quickly discharge the static electricity energy between any two ports, avoid a low-resistance channel from an input/output port to a positive power supply end, and meet the requirement of cold backup application.
The idea of the present invention is to adjust the breakdown voltage of the diode D1, the diode D2, and the diode D3 to be suitable for different process platforms under specific circumstances, and design the layout areas of the bipolar transistor Q1 and the bipolar transistor Q2 to meet different antistatic criteria, and the above discussion merely shows one specific way of the present invention, and does not limit the scope of the present invention.
Claims (3)
1. An electrostatic protection circuit for a cold backup system bipolar integrated circuit is characterized by comprising a positive power supply VS + and a negative power supply VS-, a diode D3 is arranged between the positive power supply VS + and the negative power supply VS-, the negative end of a diode D3 is connected with the positive power supply VS +, the positive end of a diode D3 is connected with the negative power supply VS-, the negative power supply VS-is connected with a PORT PORT1 and a PORT PORT2, and electrostatic protection circuits are arranged between a PORT PORT1 and a PORT PORT2 and between the negative power supply VS-;
the electrostatic protection circuit between the PORT PORT1 and the negative power supply VS-comprises a diode D1, a resistor R1 and a bipolar transistor Q1, wherein the negative terminal of the diode D1 is connected with the PORT PORT1, the positive terminal of the diode D1 is connected with the base of the bipolar transistor Q1 and one end of the resistor R1, the negative power supply VS-is connected with the other end of the resistor R1 and the emitter of the bipolar transistor Q1, and the collector of the bipolar transistor Q1 is connected with the PORT PORT 1;
the electrostatic protection circuit between the PORT PORT2 and the negative power supply VS-comprises a diode D2, a resistor R2 and a bipolar transistor Q2, wherein the negative terminal of the diode D2 is connected with the PORT PORT2, the positive terminal of the diode D2 is connected with the base of the bipolar transistor Q2 and one end of the resistor R2, the negative power supply VS-is connected with the other end of the resistor R2 and the emitter of the bipolar transistor Q2, and the collector of the bipolar transistor Q2 is connected with the PORT PORT 2;
the PORT1 and the PORT2 are input/output terminals;
the negative supply VS-is a common node.
2. An esd protection circuit for a bi-polar ic application oriented to a cold standby system according to claim 1, wherein the bipolar transistor Q1 and the bipolar transistor Q2 are both NPN transistors.
3. An esd protection circuit for bipolar ic applications in cold backup systems according to claim 1, wherein diodes D1 and D2 are zener diode.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
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| CN201910168453.8A CN109887912B (en) | 2019-03-06 | 2019-03-06 | Electrostatic protection circuit for application of bipolar integrated circuit of cold backup system |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910168453.8A CN109887912B (en) | 2019-03-06 | 2019-03-06 | Electrostatic protection circuit for application of bipolar integrated circuit of cold backup system |
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| CN109887912A CN109887912A (en) | 2019-06-14 |
| CN109887912B true CN109887912B (en) | 2021-07-13 |
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| JP2008514010A (en) * | 2004-09-16 | 2008-05-01 | サーノフ コーポレーション | Device for ESD protection |
| CN101859766A (en) * | 2009-04-13 | 2010-10-13 | 苏州芯美微电子科技有限公司 | Novel NMOS (N-channel Metal Oxide Semiconductor) clamping between power VDD (Voltage Drain Drain) and IO (Input/Output) pin and application method thereof |
| US10181719B2 (en) * | 2015-03-16 | 2019-01-15 | Analog Devices Global | Overvoltage blocking protection device |
| JP6705726B2 (en) * | 2016-09-14 | 2020-06-03 | ルネサスエレクトロニクス株式会社 | Semiconductor device |
| CN106682331A (en) * | 2016-12-30 | 2017-05-17 | 北京厚德微电技术有限公司 | Extraction of static protection structure of integrated circuit layout and intelligent design verifying method |
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