CN202309674U - Electro-static-discharge (ESD) protecting circuits and level switching circuits on high definition multimedia interface (HDMI) - Google Patents
Electro-static-discharge (ESD) protecting circuits and level switching circuits on high definition multimedia interface (HDMI) Download PDFInfo
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- CN202309674U CN202309674U CN2011204469547U CN201120446954U CN202309674U CN 202309674 U CN202309674 U CN 202309674U CN 2011204469547 U CN2011204469547 U CN 2011204469547U CN 201120446954 U CN201120446954 U CN 201120446954U CN 202309674 U CN202309674 U CN 202309674U
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Abstract
The utility model provides electro-static-discharge (ESD) protecting circuits and level switching circuits on a high definition multimedia interface (HDMI), which comprises an HDMI connected with two ESD protecting circuits. Transient voltage suppressor (TVS) array diodes are arranged inside the ESD protecting circuits, and a parasitic capacitor is a 0.5 power factor (PF) AZ1045-04F chip. An SDA port of the HDMI is connected with an SDAA level switching circuit, an SCL port is connected with an SCLA level switching circuit, and a CEC port is connected with a CEC level switching circuit. The ESD protecting circuits and the level switching circuits can achieve ESD protection, effectively absorb impact of static on a set top box and solve a problem of central processing unit (CPU) interface damage caused by voltage overshot caused by hot plug, convert 3V3 signals output by a CPU into 5V signals to meet a technical standard of HDMI 1.3, and simultaneously greatly reduces cost.
Description
[technical field]
The utility model relates to the circuit on a kind of HDMI, esd protection and level shifting circuit on particularly a kind of HDMI.
[background technology]
In recent years, along with science and technology development, it is ripe that set-top box technique is tending towards; Continuous rising along with the STB quantity required; Competition more and more fierce between the domestic STB producer, the price of bid is also constantly being forced down, and it is meagre that profit is tending towards; If the mode with complicated electronic circuit or integrated IC realizes; Will increase the unnecessary cost of STB, cause the competitiveness decline HDMI of STB on market, promptly HDMI (High Definition Multimedia Interface) is that a kind of totally digitilized image and sound transmit interface; It with the Voice & Video signal integration in single digital interface; Support uncompressed digital video, multipath audio signal, and the data communication between the receivers such as video source and LCD TV, can be used for Blu-ray player, DVD player, PVR, DTV (DTV), STB, game machine and other audio & video equipments.
According to the research of IHS iSuppli company, supported the global factory shipment amount of the equipment of HDMI interface in 2011, will rise to 6.291 hundred million from 4.777 hundred million in 2010, amplification is up to 44%.The growth rate of next three years will slow down to some extent, but will remain on 20-35%, will have about 1,300,000,000 equipment to adopt the HDMI interface by 2014.The HDMI interface will become the main equipment interfaces of consumer electronics product such as LCD TV.
The meaning of ESD (Electro-Static discharge) is " static release ".Esd event is by according to three kinds of ESD arthmetic statements of the charging process type and the transient state electrophoresis order of severity: manikin, charging device model and machine mould.Electric charge directly transmits through a series of resistor; People's finger for example; Be the most general ESD source of damage, so in order to reduce the ESD that produces owing to operating personnel's plug HDMI data wire, it is essential that the signal of each HDMI interface output is done esd protection.
The message transmission rate of HDMI interface has reached 10.2GHz/s, has higher requirement for electrostatic protection device, and the esd protection device also requires to keep the integrality of its signal except the protected data transmission line.The protection requirement on devices has littler parasitic capacitance, lower clamping performance and the line design of more optimizing.The ESD protection will if consider design margin, be strengthened to contact discharge 10kV, atmospherical discharges 30kV through the test of IEC61000-4-2Level4 at least possibly.STB adopts protection using integrated circuit chips such as CM2020 more at present, and is with high costs.
The voltage of CPU output is 3V3 again, in order to satisfy the technical specification of HDMI1.3, need I2C_SDAA, I2C_SCLA, the HDMICEC of HDMI be carried out level conversion, converts 3V3 into 5V.
[summary of the invention]
The technical problem that the utility model will solve is to provide esd protection and level shifting circuit on a kind of HDMI, and it can realize esd protection, and satisfies the technical specification of HDMI1.3.
The utility model is achieved in that esd protection and the level shifting circuit on a kind of HDMI; It comprises a HDMI interface; Said HDMI interface connects two esd protection circuits, and the SDA mouth of said HDMI interface has connected that SDAA level shifting circuit, SCL mouth have connected the SCLA level shifting circuit, the CEC mouth has connected the CEC level shifting circuit.
Further; Said SDAA level shifting circuit comprises: the I2C_SDAA mouth connects the source electrode of a NMOSFET; The grid of the one NMOSFET is connected to the 3.3V power supply, and the drain electrode of a NMOSFET is connected to first resistance, and first resistance is connected respectively to the SDA mouth, passes through the first piezo-resistance ground connection; One 5V power supply is connected to through second resistance between the drain electrode of first resistance and a NMOSFET, connects one the 3rd resistance between said 3.3V power supply and the I2C_SDAA mouth.
Further; Said SCLA level shifting circuit comprises: the I2C_SCLA mouth connects the source electrode of the 2nd NMOSFET; The grid of the 2nd NMOSFET is connected to the 3.3V power supply, and the drain electrode of the 2nd NMOSFET is connected to the 4th resistance, and the 4th resistance is connected respectively to the SCL mouth, passes through the second piezo-resistance ground connection; One 5V power supply is connected to through the 5th resistance between the drain electrode of the 4th resistance and the 2nd NMOSFET, connects one the 6th resistance between said 3.3V power supply and the I2C_SCLA mouth.
Further; Said CEC level shifting circuit comprises: HDMICEC connects the source electrode of the 3rd NMOSFET; The grid of the 3rd NMOSFET is connected to the 3.3V power supply, and the drain electrode of the 3rd NMOSFET is connected to the 7th resistance, and the 7th resistance is connected respectively to the CEC mouth, passes through the 3rd piezo-resistance ground connection; One 5V power supply is connected between the drain electrode of the 7th resistance and the 3rd NMOSFET through the 8th resistance, diode, the 9th resistance; Connect 1 the tenth resistance between said 3.3V power supply and the HDMICEC, an end ground connection of 1 the 11 resistance, the other end is connected between the 8th resistance and the diode.
Further, said esd protection circuit is that inside is TVS array diode, and parasitic capacitance is the AZ1045-04F chip of 0.5PF.
The advantage of the utility model is:
The utility model is connected esd protection circuit the inlet of HDMI interface block; Effectively absorb the cpu i/f that voltage overshoot that static brings strike and the hot plug of STB causes and damage problem, the esd protection circuit employing be two AZ1045-04F, inside is TVS array diode; Parasitic capacitance has only 0.5PF; Can satisfy the high signal quality integrality requirement of HDMI at the HW High Way of 1080P, the utility model substitutes original single chip integrated expensive circuit protection scheme through discrete device simultaneously, and is with low cost; Dependable performance can satisfy the application requirements of consumer products such as STB.
The SDA mouth of the HDMI interface of the utility model has connected that SDAA level shifting circuit, SCL mouth have connected the SCLA level shifting circuit, the CEC mouth has connected the CEC level shifting circuit; Level is changed; With the 3V3 conversion of signals of CPU output is that the 5V signal is to satisfy the technical specification of HDMI 1.3; Greatly reduce simultaneously cost again, in large batch of STB is produced, for enterprise has brought considerable economic.
[description of drawings]
Combine embodiment that the utility model is further described with reference to the accompanying drawings.
Figure 1A is the SDAA of the utility model and the structural representation of SCLA level shifting circuit.
Figure 1B is the structural representation of the CEC level shifting circuit of the utility model.
Fig. 1 C is the structural representation of the esd protection circuit of the utility model.
Fig. 1 D is the electrical block diagram of the HDMI interface of the utility model.
[embodiment]
See also shown in Figure 1A to Fig. 1 D, the embodiment of the utility model is carried out detailed explanation.
Like Figure 1A to Fig. 1 D, esd protection and level shifting circuit on a kind of HDMI of the utility model, it comprises a HDMI interface, and said HDMI interface connects two esd protection circuits, and said esd protection circuit is the AZ1045-04F chip.Because when doing esd protection, must keep the integrality of its signal.Said esd protection circuit is connected the inlet of HDMI interface, and the voltge surge that is used for absorbing static ESD and brings owing to hot plug is eliminated because the burning machine that static and hot plug bring.What said esd protection circuit adopted is two AZ1045-04F chips; The AZ1045-04F chip internal is a TVS array diode, and parasitic capacitance has only 0.5PF, can satisfy the high signal quality integrality requirement of HDMI at the HW High Way of 1080P; Satisfy air 15kV, the requirement of contact 10kV.
The SDA mouth of the said HDMI interface of the utility model has connected that SDAA level shifting circuit, SCL mouth have connected the SCLA level shifting circuit, the CEC mouth has connected the CEC level shifting circuit.
Like Figure 1A; Said SDAA level shifting circuit comprises: the I2C_SDAA mouth connects the source electrode of a NMOSFET; The grid of the one NMOSFET is connected to the 3.3V power supply, and the drain electrode of a NMOSFET is connected to first resistance, and first resistance is connected respectively to the SDA mouth, passes through the first piezo-resistance ground connection; One 5V power supply is connected to through second resistance between the drain electrode of first resistance and a NMOSFET, connects one the 3rd resistance between said 3.3V power supply and the I2C_SDAA mouth.
Said SCLA level shifting circuit comprises: the I2C_SCLA mouth connects the source electrode of the 2nd NMOSFET; The grid of the 2nd NMOSFET is connected to the 3.3V power supply; The drain electrode of the 2nd NMOSFET is connected to the 4th resistance; The 4th resistance is connected respectively to the SCL mouth, passes through the second piezo-resistance ground connection, and a 5V power supply is connected to through the 5th resistance between the drain electrode of the 4th resistance and the 2nd NMOSFET, connects one the 6th resistance between said 3.3V power supply and the I2C_SCLA mouth.
Like Figure 1B; Said CEC level shifting circuit comprises: HDMICEC connects the source electrode of the 3rd NMOSFET; The grid of the 3rd NMOSFET is connected to the 3.3V power supply, and the drain electrode of the 3rd NMOSFET is connected to the 7th resistance, and the 7th resistance is connected respectively to the CEC mouth, passes through the 3rd piezo-resistance ground connection; One 5V power supply is connected between the drain electrode of the 7th resistance and the 3rd NMOSFET through the 8th resistance, diode, the 9th resistance; Connect 1 the tenth resistance between said 3.3V power supply and the HDMICEC, an end ground connection of 1 the 11 resistance, the other end is connected between the 8th resistance and the diode.
A said NMOSFET is Q20, and the 2nd NMOSFET is Q19, and the 3rd NMOSFET is Q21.Said first resistance is RD28, and said second resistance is RD22, and said the 3rd resistance is RD27; Said the 4th resistance is RD26, and said the 5th resistance is RD20, and said the 6th resistance is RD4; Said the 7th resistance is RD37, and said the 8th resistance is RD39, and said the 9th resistance is RD29; Said the tenth resistance is RD5, and said the 11 resistance is RD40.First piezo-resistance is D15, and second piezo-resistance is D14, and the 3rd piezo-resistance is D16.Said diode is DP7.
The HDMI differential signal output of CPU need be satisfied the technical specification of HDMI 1.3, the control I2C_SDAA of HDMI, and I2C_SCLA, HDMICEC need carry out level conversion, is the 3V3 conversion of signals of CPU output that the 5V signal is to satisfy HDMI 1.3 standards.
With the SDAA level shifting circuit is example: when CPU input signal I2C_SDAA is low level; The grid of Q20 and the voltage VGS (3.3V) between the source electrode＞VGS (th) (2.5V); Thereby conducting between the drain and gate DS of Q20, output HDMI_SDA signal is a low level; When CPU input signal I2C_SDAA is high level; The grid of Q20 and source voltage VGS (0V)＜VGS (th) (2.5V); Thereby the drain and gate DS of Q20 ends, and HDMI_SDA is moving 5V on the quilt under the effect of resistance R D22, thereby realizes the interface level conversion of 3V3 to 5V.
The principle of SCLA level shifting circuit, CEC level shifting circuit is with the SDAA level shifting circuit.
Again the HDMI_CE signal in HDMI 1.3 standards, to negate irritate leakage current necessary＜1.8uA.In the CEC level shifting circuit, be exactly under the situation for the outage of source end at pull-up resistor RD29 series connection DP7, satisfy anti-irritate leakage current necessary＜regulation of 1.8UA.
Hot plug detects RD24 resistance of pin HDMIHPD series connection and carries out current limliting, is connected to the voltage-stabiliser tube DP6 voltage stabilizing of 3V3 simultaneously, will be clamped to safe voltage 3V3 to the signal of CPU.
The above; Be merely the utility model preferred embodiment; So can not limit the scope that the utility model is implemented according to this, the equivalence of promptly doing according to the utility model claim and description changes and modifies, and all should still belong in the scope that the utility model contains.
Claims (5)
1. esd protection and the level shifting circuit on the HDMI; It comprises a HDMI interface; It is characterized in that: said HDMI interface connects two esd protection circuits, and the SDA mouth of said HDMI interface has connected that SDAA level shifting circuit, SCL mouth have connected the SCLA level shifting circuit, the CEC mouth has connected the CEC level shifting circuit.
2. esd protection and level shifting circuit on a kind of HDMI according to claim 1; It is characterized in that: said SDAA level shifting circuit comprises: the I2C_SDAA mouth connects the source electrode of a NMOSFET; The grid of the one NMOSFET is connected to the 3.3V power supply; The drain electrode of the one NMOSFET is connected to first resistance; First resistance is connected respectively to the SDA mouth, passes through the first piezo-resistance ground connection, and a 5V power supply is connected to through second resistance between the drain electrode of first resistance and a NMOSFET, connects one the 3rd resistance between said 3.3V power supply and the I2C_SDAA mouth.
3. esd protection and level shifting circuit on a kind of HDMI according to claim 1; It is characterized in that: said SCLA level shifting circuit comprises: the I2C_SCLA mouth connects the source electrode of the 2nd NMOSFET; The grid of the 2nd NMOSFET is connected to the 3.3V power supply; The drain electrode of the 2nd NMOSFET is connected to the 4th resistance; The 4th resistance is connected respectively to the SCL mouth, passes through the second piezo-resistance ground connection, and a 5V power supply is connected to through the 5th resistance between the drain electrode of the 4th resistance and the 2nd NMOSFET, connects one the 6th resistance between said 3.3V power supply and the I2C_SCLA mouth.
4. esd protection and level shifting circuit on a kind of HDMI according to claim 1; It is characterized in that: said CEC level shifting circuit comprises: HDMICEC connects the source electrode of the 3rd NMOSFET; The grid of the 3rd NMOSFET is connected to the 3.3V power supply; The drain electrode of the 3rd NMOSFET is connected to the 7th resistance; The 7th resistance is connected respectively to the CEC mouth, passes through the 3rd piezo-resistance ground connection, and a 5V power supply is connected to through the 8th resistance, diode, the 9th resistance between the drain electrode of the 7th resistance and the 3rd NMOSFET, connects 1 the tenth resistance between said 3.3V power supply and the HDMICEC; One end ground connection of 1 the 11 resistance, the other end is connected between the 8th resistance and the diode.
5. esd protection and level shifting circuit on a kind of HDMI according to claim 1 is characterized in that: said esd protection circuit is that inside is TVS array diode, and parasitic capacitance is the AZ1045-04F chip of 0.5PF.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204469547U CN202309674U (en) | 2011-11-11 | 2011-11-11 | Electro-static-discharge (ESD) protecting circuits and level switching circuits on high definition multimedia interface (HDMI) |
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| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN2011204469547U CN202309674U (en) | 2011-11-11 | 2011-11-11 | Electro-static-discharge (ESD) protecting circuits and level switching circuits on high definition multimedia interface (HDMI) |
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| CN202309674U true CN202309674U (en) | 2012-07-04 |
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| CN2011204469547U Expired - Fee Related CN202309674U (en) | 2011-11-11 | 2011-11-11 | Electro-static-discharge (ESD) protecting circuits and level switching circuits on high definition multimedia interface (HDMI) |
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111740400A (en) * | 2020-06-22 | 2020-10-02 | 广东九联科技股份有限公司 | Circuit and method for reducing influence of ESD device on high-speed signal |
| CN112202439A (en) * | 2020-03-31 | 2021-01-08 | 华为技术有限公司 | Capacitor isolation circuit, interface module, chip and system |
| CN115933853A (en) * | 2023-03-13 | 2023-04-07 | 电信科学技术第五研究所有限公司 | Storage circuit based on acquire electric energy through stealing electric mode on signal line |
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2011
- 2011-11-11 CN CN2011204469547U patent/CN202309674U/en not_active Expired - Fee Related
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112202439A (en) * | 2020-03-31 | 2021-01-08 | 华为技术有限公司 | Capacitor isolation circuit, interface module, chip and system |
| CN112202439B (en) * | 2020-03-31 | 2021-09-07 | 华为技术有限公司 | Capacitor isolation circuit, interface module, chip and system |
| WO2021196958A1 (en) * | 2020-03-31 | 2021-10-07 | 华为技术有限公司 | Capacitive isolation circuit, interface module, chip, and system |
| CN111740400A (en) * | 2020-06-22 | 2020-10-02 | 广东九联科技股份有限公司 | Circuit and method for reducing influence of ESD device on high-speed signal |
| CN115933853A (en) * | 2023-03-13 | 2023-04-07 | 电信科学技术第五研究所有限公司 | Storage circuit based on acquire electric energy through stealing electric mode on signal line |
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| C14 | Grant of patent or utility model | ||
| GR01 | Patent grant | ||
| CF01 | Termination of patent right due to non-payment of annual fee |
Granted publication date: 20120704 Termination date: 20161111 |
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| CF01 | Termination of patent right due to non-payment of annual fee |