Additional internal or add-on parts to a fixed voltage regulator to prevent the output voltage from exceeding a preset limit if internal voltage regulation fails. Some OVP designs include an SCR to short the output and blow a fuse, rather than risk damage to downstream hardware.
Questions tagged [over-voltage-protection]
294 questions
34
votes
2 answers
What is an "XY" rated safety capacitor, exactly?
Please help me understand this. In a prominent, 480v, 6kW AC servo drive, across three input phases, three 22mm "XY" class 10nF caps are placed for EMI suppression. Also, from these three phases, three of the exact same "XY" caps go to chassis…
rdtsc
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16
votes
5 answers
Protect DC Circuit from too much voltage
How do I protect a 3v DC circuit from being damaged, if someone accidentally plugs in a 12v power supply? The circuit will draw much less than 1 amp.
flamingpenguin
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12
votes
2 answers
How does this overvoltage protection work?
I was looking around for low cost and effective overvoltage protection, and I found this from this page:
With this part list:
RXE025 - 250 mA PTC resettable fuse
Zener diode – 5V6, 1 watt
Resistor – 1K ohm, 1 watt
Transistor – BD139 (NPN medium…
VirtApp
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9
votes
3 answers
Why am I destroying MOSFETs in this overvoltage protection circuit?
I am designing a pro audio-video product that runs from a nominal 24 V 5 A off-the-shelf computer "brick" that has worldwide certifications. My customer has very little tech savvy, so I want to protect my rather expensive PCB from someone connecting…
Brian Dotson
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9
votes
2 answers
Self-resetting crowbar circuit for over-voltage protection
I'm trying to design an over-voltage protection circuit that doesn't rely on custom chips (the chip shortage has shown the danger of relying on this), so I put together a crowbar circuit like this:
I used a polyfuse since I don't want to have to…
Colin
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8
votes
2 answers
How can I protect MCU GPIO input pins from accidental overvoltage by user error?
I'm using the SM32F207Z MCU for input/outputs digital processing. The MCU will also handle Ethernet communications. I/O port functions will be provided by 16 + 16 digital input/outputs.
Our application will read logic levels from GPIO pins…
Suvi_Eu
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8
votes
1 answer
Designing an effective power supply for embedded products
I'm currently designing several embedded microcontroller products to be powered from a wall outlet. I plan to use wall-wart power supplies to give an input of approximately 5-9V DC but I want the input of my device to work at up to 30V just for the…
dylanweber
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7
votes
3 answers
Adding hysteresis to over-voltage protection using comparator
I am trying to add hysteresis into my over-voltage detection circuit. The output of the comparator should be high as long as the supply voltage is below 14 V.
The circuit works perfectly fine, but I would like to add hysteresis, so that after going…
Axodarap
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7
votes
4 answers
For how long should I charge my dead car battery without damaging it?
I drained by accident my car's battery. When I connect it now to a multimeter it shows 3V. I connected the battery already to a trickle charger and I would like to know for how long I should charge it, so that I don't damage it by overcharging. E.g.…
NeStack
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7
votes
8 answers
Is the overvoltage protection used in this circuit a normal way of doing it?
The circuit is from a clip on YouTube. VCC is from a stepper motor generator and varies between ~0-30 volts DC.
From what I understand, and please correct me if I am wrong, when the voltage gets too high the opamp goes high and the MOSFET opens and…
Dostoevskie
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7
votes
2 answers
FPGA over-voltage protection for input trigger signal
I don't have much experience with PCB design, but I am currently designing one to connect together several components for a work project. One of these components is connecting an external trigger signal to an input pin on a Neso Artix 7 FPGA board.…
hexahedronest
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7
votes
2 answers
"shark teeth"-like PCB feature in high voltage section of modern HDTV
I found this tooth-like non-masked, solder-covered trace pattern on modern single board HDTV.
It's in the 120VAC "HOT" section of the switch-mode PS.
Looks like some sort of spark gap or protection feature. There are two of them, one with 3 "teeth"…
Christopher Allen
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7
votes
1 answer
Radio module resetting when fluorescent tube switched on/off
I have a PCB powered by an IRM-30-12 power supply (230VAC to 12VDC). On this PCB, I have a MRF24J40MD from Microchip and a Udooneo to drive it + a 5VDC regulator and the 3.3VDC of the Udooneo.
After installing over 300 units in different places, I…
Carton_
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6
votes
1 answer
Overvoltage and reverse polarity protection
There are two well-known circuits well described in the Internet, including this site:
Reverse polarity protection with P-channel MOSFET;
Overvoltage protection with SCR and Zener (so-called "crowbar").
I want to combine them like shown…
Zhenek
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5
votes
2 answers
Overvoltage protection circuit transistor draws 2x load current then suddenly stablizes
I've built an over voltage protection circuit according to this schematic by Maxim:
If the load is low power consumption like MCU or other ICs, it works just fine.
If the load is higher for example, 350mA (maybe DCDC circuit,) the circuit starts to…
Travis Su
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