By LEIDITECH | 07 May 2024 | 0 Comments
Overvoltage in the circuit(OVP)protection circuit
Hardware engineers often encounter this situation，such aschipThe working voltage of is 5V ,But the power supply voltage may exceed 6 due to surges or static electricity.5VOr higher，And the chip can withstand the highest working voltage of 6.3V，If you choose toTVS（ESD）, TVSBecause of clamping voltageVCOver 6.5V ，So it cannot provide protection，So it caused many chips to be damaged,There are many situations like this，At this point, you can choose toOVP, OVPCan withstand voltage exceeding threshold voltage（For example, 6.1V，Or adjust to the appropriate threshold voltage）Turn off power when needed，Protecting downstream chips，andOVPCan withstand a relatively high range of input voltage ，There are over twenty of themV ，Some are in their thirtiesV ,Below is a detailed understanding of this useful overvoltage protection circuit OVP。
one、What isOVP
OVP（Over Voltage ProtectionOvervoltage protection）：Namely overvoltage protection，Turn off the power or pause output when the voltage exceeds the preset level，Provided protection for the subsequent circuit,To avoid damage to the subsequent circuit caused by high input voltage。
There are many ways to protect against overvoltage，However, electronic devices used on mobile phones or with limited space，Often adoptedOVPchip。Affordable price，And the threshold is controllable，rightPCBThe layout saves space。
Shanghai Leimao has launched several models OVPOvervoltage protection chip，First, let's briefly introduce the followingOVPBasic principles of。
2、OVPBasic Principles
The above picture showsOVP Internal Block Diagram，The principle is that when the input voltage is too high，The internal logic and driving circuit will be turned offMOSFET，At this point, the input and output will be disconnected，No output voltage，Plays a role in protecting the backend。When the input voltage returns to normal operating voltage，OVPReopenMOSFET，Normal output voltage。
The schematic diagram of overvoltage protection is as follows：
When the input voltageVINGreater than or equal to 5V，Less than 6.1V( threshold voltage ）：Vout =Vin
When the input voltage exceeds the threshold voltage of 6.1V, Less than the highest input voltageVin max: Vout =0
When the input voltage exceeds the threshold voltage,insideMOSFET Will be on 1us Internal fast shutdown，Make no output voltage，Protect the secondary circuit。
3、OVPmain parameter
l input voltage Vin: OVPThe input voltage range is generally wide，But it must not exceed the maximum input voltageVin(max)。
l OVP threshold voltage ： This voltage needs to be greater than the voltage range protected by the subsequent stage and leave a certain margin。YesOVPIt's a fixed voltage，And some are adjustable。
l Conduction resistance Ron: Conduction resistanceRonIt is a very critical parameter，Because the current will pass throughMOS，So the conducting resistance determines the processMOSPressure drop after，Due to power loss，Conduction resistance determines the amount of heat generated by a chip,thereforeRon The smaller the better。
l Turn off timeToff：OVPDiscovering the time difference from overvoltage to shutdown output，The shorter the time, the better。
l SomeOVP WithOCP(Overcurrent protection）And over temperature protection（OTP）function。
The above parameters can be specifically referred to in the specification sheet。
4. OVPAttention to component application
Due to the presence of internal resistance，Therefore, thermal design factors need to be considered。
Due toOVPThe input voltage of the chip is also limited，To prevent static electricity and other factors from causingOVPChip burnout，You can add aTVS，thisTVSRated voltage of（Reverse cut-off voltageVRWM）Should be higher than the input power voltage of this circuit，clamping voltageVclampShould be lower thanOVPThe highest input voltage of the chip。
5. Shanghai LeimaoOVP
The above models are displayed
6. OVPSpecifications
aboutOVP For specific applications and selection, please contact Shanghai LeimaoEMC Little brother。
Shanghai Leimao Professional R&D and SalesESD，TVS，TSS，GDT，MOV，MOSFET，RectifierOther products。We are committed to providing customers with high-quality products，To protect the circuit from static interference and voltage fluctuations。Our products cover a wide range of application areas，Including electronics、communication、computer、automobile、Medical and other industries。We have an experienced R&D team，Capable of providing personalized customization services based on customer needs，Provide customers with the highest quality solutions。
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