CN109066627B - Protection circuit for hot plug detection port with HPD and ESD - Google Patents
Protection circuit for hot plug detection port with HPD and ESD Download PDFInfo
- Publication number
- CN109066627B CN109066627B CN201811065498.4A CN201811065498A CN109066627B CN 109066627 B CN109066627 B CN 109066627B CN 201811065498 A CN201811065498 A CN 201811065498A CN 109066627 B CN109066627 B CN 109066627B
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- Prior art keywords
- resistor
- hot plug
- circuit
- hpd
- triode
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/02—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess current
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/04—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage
- H02H9/045—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection responsive to excess voltage adapted to a particular application and not provided for elsewhere
Abstract
The invention relates to a protection circuit for a hot plug detection port with both HPD and ESD, which comprises a current limiting circuit, a voltage clamping circuit and a negative voltage coupling circuit, wherein the current limiting circuit comprises a first resistor connected between a hot plug signal input port and a hot plug signal output port in the hot plug detection port; the voltage clamping circuit comprises a triode, a second resistor and a third resistor, wherein a collector of the triode is connected to the hot plug signal output port, and an emitter of the triode is connected with a GND (ground) terminal; one end of the second resistor and one end of the third resistor are respectively connected to a hot plug signal output port, the other end of the second resistor is connected to the base electrode of the triode, and the other end of the third resistor is connected with a GND end; the negative voltage coupling circuit comprises a series circuit formed by connecting a fourth resistor and a first capacitor in series, one end of the series circuit is connected to the hot plug signal input port, and the other end of the series circuit is connected to the base electrode of the triode.
Description
The application is a divisional application of a parent application named as 'protection circuit for hot plug detection port' with application number of 201710718434.9 and application date of 2017, 08 and 21.
Technical Field
The invention relates to the field of HDMI circuits, in particular to a protection circuit which has HPD and ESD and is used for hot plug detection ports.
Background
In the prior art, a protection circuit for a HOT PLUG DETECTION (HOT PLUG DETECTION) port of an HDMI circuit is often implemented by using an ESD device or a zener diode. However, ESD devices are more standard and expensive, and zener diodes are slow to respond and prone to failure, so there is a need for an improved protection circuit.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: the protection circuit for the hot plug detection port is low in cost and has better protection effect.
In order to solve the technical problems, the invention adopts the technical scheme that:
a protection circuit for a hot plug detection port comprises a current limiting circuit, a voltage clamping circuit and a negative voltage coupling circuit, wherein the current limiting circuit comprises a first resistor connected between a hot plug signal input port and a hot plug signal output port in the hot plug detection port; the voltage clamping circuit comprises a triode, a second resistor and a third resistor, wherein a collector of the triode is connected to the hot plug signal output port, and an emitter of the triode is connected with a GND (ground potential) end; one end of the second resistor and one end of the third resistor are respectively connected to the base electrode of the triode, the other end of the second resistor is connected to the hot plug signal output port, and the other end of the third resistor is connected with a GND (ground) end; the negative voltage coupling circuit comprises a series circuit formed by connecting a fourth resistor and a first capacitor in series, one end of the series circuit is connected to the hot plug signal input port, and the other end of the series circuit is connected to the base electrode of the triode.
The invention has the beneficial effects that: the mode of adding a triode and a resistor capacitor is adopted to replace an expensive ESD device, so that the cost is reduced, and the HPD detection function is realized; and the negative-voltage ESD test function is further realized by utilizing the RC negative-voltage coupling circuit.
Drawings
Fig. 1 is a circuit configuration diagram of a protection circuit according to an embodiment of the present invention;
fig. 2 is a block diagram of an application of a protection circuit according to an embodiment of the present invention.
Description of reference numerals:
1. a current limiting circuit; 2. a voltage clamp circuit; 3. a negative voltage coupling circuit; r1, a first resistor; r2, a second resistor; r3, a third resistor; r4, fourth resistor;
q1, transistor; GND, GND terminal; c1, a first capacitor; c2, a second capacitor; HPD _ IN, signal input port; HPD _ OUT and a signal output port; 10. an HPD detection protection circuit; 11. a CPU; 12. a linker; 13. a display.
Detailed Description
In order to explain technical contents, achieved objects, and effects of the present invention in detail, the following description is made with reference to the accompanying drawings in combination with the embodiments.
As shown IN fig. 1, an embodiment of the present invention provides a protection circuit for a hot swap detection port, including a current limiting circuit 1, a voltage clamping circuit 2, and a negative voltage coupling circuit 3, where the current limiting circuit 1 includes a first resistor R1 connected between a hot swap signal input port HPD _ IN and a hot swap signal output port HPD _ OUT IN the hot swap detection port; the voltage clamping circuit 2 comprises a triode Q1, a second resistor R2 and a third resistor R3, the collector of the triode Q1 is connected to the hot plug signal output port HPD _ OUT, and the emitter of the triode Q1 is connected with a GND (ground) terminal GND; one end of the second resistor R2 and one end of the third resistor R3 are respectively connected to the base of the triode Q1, the other end of the second resistor R2 is connected to the hot plug signal output port HPD _ OUT, and the other end of the third resistor R3 is connected to a GND end; the negative voltage coupling circuit 3 includes a series circuit formed by connecting a fourth resistor R4 and a first capacitor C1 IN series, one end of the series circuit is connected to the hot plug signal input port HPD _ IN, and the other end of the series circuit is connected to the base of the transistor Q1.
As can be seen from fig. 2, the protection circuit 10 for hot plug detection port is connected between the CPU11 and the linker 12. The link 12 is an HDMI socket for inserting an HDMI plug. A line for transmitting signals such as I2C is provided between the CPU11 and the linker 12, and a signal line for transmitting an HPD detection signal is also provided. And the port of the signal line on the CPU side is referred to as an output port for HPD detection signal HPD _ OUT, and the port on the side of the chain 12 is referred to as an input port for HPD detection signal HPD _ IN. And an HDMI cable is used to connect the link 12 with the display 13.
IN the protection circuit 10, with the transistor Q1, the second resistor R2, and the third resistor R3 constituting the voltage clamp circuit 2, when there is a 5V positive voltage on the signal input port HPD _ IN (for example, when an HDMI cable from a display is inserted into the link 12), the voltage division of the 5V positive voltage by the first resistor R1, the second resistor R2, and the third resistor R3 is insufficient to cause the transistor Q1 to be turned on (i.e., the Q1 is IN an off state), that is, the voltage on the base of the transistor Q1 is not large enough, so that the signal output port HPN _ OUT supplies a positive voltage signal to the CPU, and the CPU can detect that the HDMI cable is inserted.
When the input port of the HPD _ IN has a positive voltage or static electricity input which is more than 5V, after the partial voltage of the resistors R1, R2 and R3 is applied, the voltage at the transistor Q1 is enough to enable the transistor to be conducted, so that the transistor pulls down the HPD _ OUT port, and the voltage clamp circuit can protect the GPIO port of the CPU (namely the CPU port to which the HPD _ OUT is connected) from being damaged by the high voltage from the HPD _ IN.
In addition, the protection circuit utilizes a series circuit consisting of the first capacitor C1 and the fourth resistor R4 as a negative voltage coupling circuit to introduce a negative voltage electrostatic charge leakage current into the transistor Q1, and the Q1 is turned on to realize detection. Specifically, when a negative voltage test is performed on the GND terminal, the potential of the GND terminal on the PCB (IN fact, the entire potential of the entire circuit board including the power supply changes IN the same direction as the GND) changes abruptly IN the negative direction with respect to the ground (earth), and since the connection between the HPD _ OUT and the HPD _ IN is high-resistance (due to the presence of the first resistor R1), the conductor potential of the HPD signal line IN the HDMI cable cannot change abruptly when the potential of the GND terminal on the circuit board changes abruptly IN the negative direction, but a current bleeding path is formed by the ESD circuit inside the CPU, the first resistor R1, and the HPD signal line IN the cable, and thus a potential difference is formed across the first resistor R1. The potential difference can be charged to the first capacitor C1 through the fourth resistor R4, so that the negative coupling circuit 3 introduces the potential difference across the first resistor R1 to the transistor Q1 through the first capacitor C1 and the fourth resistor R4. When the charging voltage at the terminal C1 reaches the turn-on voltage of the base of the transistor Q1, the terminal C-E of the transistor Q1 is turned on, and a low level pulse is generated at the HPD _ OUT terminal, thereby implementing the negative voltage protection function.
When a user pulls out the HDMI cable, if static electricity exists in the human body, the protection circuit 10 also plays a role of ESD protection as above.
IN a further embodiment, the negative voltage coupling circuit 3 further comprises a second capacitor C2, and the second capacitor C2 is connected between the hot plug signal input port HPD _ IN and the GND terminal. The second capacitor C2 may be used to filter the input signal to the HPD _ IN port to reduce signal interference. In an alternative example, the second capacitor has a capacitance value of 1 nF.
In a further embodiment, the first resistor R1 has a resistance value between 500 ohms and 2K ohms.
In a further embodiment, the second resistor R2 has a resistance value between 40K ohms and 50K ohms and the third resistor has a resistance value between 5K ohms and 20K ohms.
And the clamp voltage in the voltage clamp in the protection circuit is approximately: (R2+ R3)/R3 × 0.55V (threshold value of transistor conduction is 0.7V, where 0.55V is selected as the threshold voltage caused by the transistor); the voltage parameter range of the current HDMI HPD is 2.7V-5.3V, and the GPIO voltage of the CPU is 3.3V. Therefore, the resistance values of the resistors R2 and R3 are properly adjusted to meet the detection requirement.
In a further embodiment, the fourth resistor R4 has a resistance value between 1K ohm and 5K ohm, and the first capacitor C1 has a capacitance value between 50nF and 200 nF. By appropriate selection of the values of R4 and C1, a better drainage effect can be achieved.
Referring to fig. 1, a first embodiment of the present invention is:
a protection circuit for a hot plug detection port comprises a current limiting circuit 1, a voltage clamping circuit 2 and a negative voltage coupling circuit 3, wherein the current limiting circuit 1 comprises a first resistor R1 connected between a hot plug signal input port HPD _ IN and a hot plug signal output port HPD _ OUT IN the hot plug detection port; the voltage clamping circuit 2 comprises a triode Q1, a second resistor R2 and a third resistor R3, the collector of the triode Q1 is connected to the hot plug signal output port HPD _ OUT, and the emitter of the triode Q1 is connected with the GND end; one end of the second resistor R2 and one end of the third resistor R3 are respectively connected to the base of the triode Q1, the other end of the second resistor R2 is connected to the hot plug signal output port HPD _ OUT, and the other end of the third resistor R3 is connected with a GND end; the negative voltage coupling circuit 3 includes a series circuit formed by connecting a fourth resistor R4 and a first capacitor C1 IN series, one end of the series circuit is connected to the hot plug signal input port HPD _ IN, and the other end of the series circuit is connected to the base of the transistor Q1.
The negative voltage coupling circuit 3 further comprises a second capacitor C2, the second capacitor C2 is connected between the hot plug signal input port HPD _ IN and the GND terminal, and the capacitance value of the second capacitor is 1 nF. Further, the resistance of the first resistor R1 is 1K ohm, the resistance of the second resistor R2 is 43K ohm, the resistance of the third resistor is 10K ohm, the resistance of the fourth resistor R4 is 2.2K ohm, and the capacitance of the first capacitor C1 is 100 nF.
In summary, the protection circuit for hot plug detection port provided by the invention adopts a mode of adding a resistor and a capacitor to a triode to replace an expensive ESD device, thereby reducing the cost and realizing the HPD detection function; the negative-voltage ESD test function is further realized by matching the negative-voltage coupling circuit with the triode, and the device has good practical value.
The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent changes made by using the contents of the present specification and the drawings, or applied directly or indirectly to the related technical fields, are included in the scope of the present invention.
Claims (5)
1. A protection circuit for hot plug detection port with HPD and ESD comprises a current limiting circuit, a voltage clamping circuit and a negative voltage coupling circuit,
the current limiting circuit comprises a first resistor connected between a hot plug signal input port and a hot plug signal output port in the hot plug detection port;
the voltage clamping circuit comprises a triode, a second resistor and a third resistor, wherein a collector of the triode is connected to the hot plug signal output port, and an emitter of the triode is connected with a GND (ground potential) end;
one end of the second resistor and one end of the third resistor are respectively connected to the base electrode of the triode, the other end of the second resistor is connected to the hot plug signal output port, and the other end of the third resistor is connected with a GND (ground) end;
the negative voltage coupling circuit comprises a series circuit formed by connecting a fourth resistor and a first capacitor in series, one end of the series circuit is connected to the hot plug signal input port, and the other end of the series circuit is connected to the base electrode of the triode;
the negative-voltage coupling circuit further comprises a second capacitor, and the second capacitor is connected between the hot plug signal input port and a GND (ground) terminal;
the resistance value of the first resistor is between 500 ohms and 2K ohms;
the resistance value of the second resistor is between 40K ohm and 50K ohm, and the resistance value of the third resistor is between 5K ohm and 20K ohm;
the resistance value of the fourth resistor is between 1K ohm and 5K ohm, and the capacitance value of the first capacitor is between 50nF and 200 nF;
the protection circuit is connected between the CPU and the linker, and the linker is an HDMI socket for inserting an HDMI plug; the HDMI cable is used to connect the link with the display.
2. The protection circuit for a hot swap detection port with both HPD and ESD as claimed in claim 1, wherein the second capacitor has a capacitance of 1 nF.
3. The protection circuit for a hot swap detection port with both HPD and ESD of claim 1, wherein the second resistor has a resistance of 43K ohms and the third resistor has a resistance of 10K ohms.
4. The protection circuit for a hot swap detection port with both HPD and ESD as claimed in claim 1, wherein the fourth resistor has a resistance of 2.2K ohms and the first capacitor has a capacitance of 100 nF.
5. The protection circuit for hot plug detection port with both HPD and ESD as claimed in claim 1, wherein there is a line for transmitting I2C signal between CPU and linker, further comprising a signal line for transmitting HPD detection signal.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811065498.4A CN109066627B (en) | 2017-08-21 | 2017-08-21 | Protection circuit for hot plug detection port with HPD and ESD |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201811065498.4A CN109066627B (en) | 2017-08-21 | 2017-08-21 | Protection circuit for hot plug detection port with HPD and ESD |
| CN201710718434.9A CN107317316B (en) | 2017-08-21 | 2017-08-21 | The protection circuit of port is detected for hot plug |
Related Parent Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201710718434.9A Division CN107317316B (en) | 2017-08-21 | 2017-08-21 | The protection circuit of port is detected for hot plug |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN109066627A CN109066627A (en) | 2018-12-21 |
| CN109066627B true CN109066627B (en) | 2020-02-14 |
Family
ID=60176434
Family Applications (4)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811065430.6A Active CN109378808B (en) | 2017-08-21 | 2017-08-21 | A kind of protection circuit for hot plug detection port of low cost |
| CN201710718434.9A Active CN107317316B (en) | 2017-08-21 | 2017-08-21 | The protection circuit of port is detected for hot plug |
| CN201811065444.8A Active CN109245074B (en) | 2017-08-21 | 2017-08-21 | Protection circuit for the hot plug detection port between CPU and linker |
| CN201811065498.4A Expired - Fee Related CN109066627B (en) | 2017-08-21 | 2017-08-21 | Protection circuit for hot plug detection port with HPD and ESD |
Family Applications Before (3)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201811065430.6A Active CN109378808B (en) | 2017-08-21 | 2017-08-21 | A kind of protection circuit for hot plug detection port of low cost |
| CN201710718434.9A Active CN107317316B (en) | 2017-08-21 | 2017-08-21 | The protection circuit of port is detected for hot plug |
| CN201811065444.8A Active CN109245074B (en) | 2017-08-21 | 2017-08-21 | Protection circuit for the hot plug detection port between CPU and linker |
Country Status (1)
| Country | Link |
|---|---|
| CN (4) | CN109378808B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN108879649B (en) * | 2018-07-02 | 2019-12-06 | 京东方科技集团股份有限公司 | display device and plug-in protection device thereof |
| CN117220250B (en) * | 2023-11-09 | 2024-03-01 | 浙江地芯引力科技有限公司 | Power protection circuit, chip and data line |
Family Cites Families (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6614633B1 (en) * | 1999-03-19 | 2003-09-02 | Denso Corporation | Semiconductor device including a surge protecting circuit |
| JP4866672B2 (en) * | 2006-07-27 | 2012-02-01 | ルネサスエレクトロニクス株式会社 | Load drive circuit |
| CN201118817Y (en) * | 2007-11-30 | 2008-09-17 | 青岛海信电器股份有限公司 | Thermal plug interface circuit and TV with circuit |
| US8514532B2 (en) * | 2009-06-18 | 2013-08-20 | Conexant Systems, Inc. | Electrostatic discharge protection circuit |
| CN201629569U (en) * | 2010-03-18 | 2010-11-10 | 深圳创维－Rgb电子有限公司 | Over-voltage protection circuit of USB interface |
| CN102457051B (en) * | 2010-10-19 | 2015-07-22 | 台达电子工业股份有限公司 | Transient current suppression device |
| CN102025143B (en) * | 2010-11-10 | 2013-07-03 | 中国兵器工业集团第二一四研究所苏州研发中心 | Transient voltage-resistant delay circuit |
| CN202353545U (en) * | 2011-12-06 | 2012-07-25 | 深圳市共进电子股份有限公司 | Level switch interface circuit based on hot plug from TTL (transistor-transistor logic)/CMOS (complementary metal-oxide-semiconductor transistor) to RS (recommend standard) 232 |
| US8760829B2 (en) * | 2012-01-23 | 2014-06-24 | Texas Instruments Incorporated | Low-impedance high-swing power supply with integrated high positive and negative DC voltage protection and electro-static discharge (ESD) protection |
| CN202586257U (en) * | 2012-04-20 | 2012-12-05 | 华映视讯（吴江）有限公司 | Hot-swap protection system |
| CN203218876U (en) * | 2013-03-21 | 2013-09-25 | 广州金升阳科技有限公司 | A positive and negative surge protection circuit |
| CN203573308U (en) * | 2013-11-15 | 2014-04-30 | 深圳市航盛电子股份有限公司 | HDMI hot plugging detection circuit |
| US9484739B2 (en) * | 2014-09-25 | 2016-11-01 | Analog Devices Global | Overvoltage protection device and method |
| CN204559104U (en) * | 2015-04-29 | 2015-08-12 | 浪潮软件集团有限公司 | Low-cost HDMI interface power supply protection circuit |
| CN205105319U (en) * | 2015-10-20 | 2016-03-23 | 重庆惠科金扬科技有限公司 | HDMI interface circuit |
| CN206097104U (en) * | 2016-08-08 | 2017-04-12 | Tcl王牌电器(惠州)有限公司 | Hot plug protection circuit and electronic equipment |
| CN107546731A (en) * | 2017-09-20 | 2018-01-05 | 奕瑞影像科技（太仓）有限公司 | A kind of plug-and-play circuit, interface circuit and electronic equipment |
-
2017
- 2017-08-21 CN CN201811065430.6A patent/CN109378808B/en active Active
- 2017-08-21 CN CN201710718434.9A patent/CN107317316B/en active Active
- 2017-08-21 CN CN201811065444.8A patent/CN109245074B/en active Active
- 2017-08-21 CN CN201811065498.4A patent/CN109066627B/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN107317316A (en) | 2017-11-03 |
| CN109245074A (en) | 2019-01-18 |
| CN109066627A (en) | 2018-12-21 |
| CN109378808A (en) | 2019-02-22 |
| CN109378808B (en) | 2019-09-27 |
| CN109245074B (en) | 2019-11-19 |
| CN107317316B (en) | 2018-11-02 |
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