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3
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1answer
93 views

Transient protection to prevent microcontroller freeze - Selecting MOVs and TVS diodes

I have a circuit which contains an offline switching SMPS circuit (based on viper22a) converting 220V to 5V regulated down to 3.3V using linear regulator IC. This powers up an ESP wifi module and ...
1
vote
1answer
47 views

Are voltage transients on LTspice simulations significant?

I (incorrectly*) modeled this simple answer in LTspice IV and am seeing seemingly random instantenous voltage spikes up to +/-1kV on the output of the depletion nMOSFET. Are these real? If so, are ...
3
votes
1answer
57 views

Where to put a spark gap for ESD protection--to an isolated “GND” or to protective earth?

I am designing some PCBs for a system that runs on a fully-isolated DC power supply. I have three power inputs: Protective earth (connected directly to the line earth of a three-pin US 120V AC power ...
2
votes
5answers
192 views

How to remove spikes from switching transistor?

I am building a steady current source which delivers steady current (0-20mA) to an LED. The brightness of the LED (current) is controlled through a potentiometer's voltage and a voltage follower as ...
0
votes
2answers
111 views

Spark Suppressor Question

I built a timer for my water heater and have a question about spark suppression. I am using a 120v house timer 1875W to operate a Packard (240B) 2 pole 40A 120v coil relay. The output of the relay ...
1
vote
2answers
66 views

Ethernet surge and protection

I recently worked with a client who experienced a transient on their Ethernet cabling. As you can see, no actual PCs were damaged, only the Ethernet cards of some machines. We don't know where the ...
4
votes
1answer
221 views

Clamping Inductive Kickback in AC Circuits

I want to eliminate/clamp the inductive kickback that would result from turning off a large inductor, such as a relay or a transformer. In a DC circuit, I would use a diode to flywheel the current. ...
0
votes
0answers
51 views

Why would you use both Varistors, TVS diodes in the design?

A similar question has been asked but not really answered here. For transients occurring in class-2 AC powered devices, why would an MOV or just a TVS not be enough and most design include both?
0
votes
1answer
111 views

Correct design for large contactor circuit?

After some advice here I'm wondering if this is the correct design of my circuit. I'm now using a SSR as the control device to the contactor. The diode, I believe, should not only protect the SSR ...
0
votes
0answers
47 views

Overcoming the voltage gap between a TVS diode's reverse stand off voltage and max clamping voltage

Consider the following scenario (all values are just for example): A device has a max input voltage of 9V and has components where the absolute maximum voltage is 15V. In order to protect against ...
1
vote
1answer
110 views

Does this Schottky provide MOSFET transient protection?

I'm studying the schematic for an electronic load available as a kit from Jameco: http://www.jameco.com/Jameco/Products/ProdDS/2161107%20Schematic.pdf There is a Schottky diode shunting the ...
1
vote
3answers
305 views

Why do designers use a series diode and zener for coil suppression rather than just a zener?

I understand the use of the Zener but what I don't understand is one topology uses two components, but why can't the other topology be used ? simulate this circuit – Schematic created ...
2
votes
1answer
263 views

How do I model an over voltage spike on LTSpice? Any circuit example

I am doing project, I am trying to simulate an overvoltage/under voltage protection controller on LTSpice. How do I create overvoltage/unudervoltage on a source? For example a transient voltage spike? ...
1
vote
2answers
109 views

Are all snubbers interchangeale?

There are different kinds of snubbers that can be used. I know of 3, but there could be more. D RC RCD If an certain circuit uses a diode, can I swap it for an RC ? Or if a circuit has an RC, can ...
2
votes
1answer
646 views

How to conduct “Transient Power” measurement according to ETSI EN 300 220-1 (v2.4.1)?

Background Info The company I work for builds Active RFID hardware that needs to conform to the regulations defined in ETSI EN 300 220 (Part 1). Our working frequency is 433.92 MHz. I am responsible ...
2
votes
1answer
204 views

Is a 9.6µs over-voltage transient long enough to fry my circuit (Details inside)?

I am designing a board for a 12V automotive environment, with a variety of input voltage transients including load dump and permanent 24V over-voltage. I am using a TVS at the input to clamp to around ...
8
votes
2answers
822 views

Transient voltage suppression diode not doing its job

I have a circuit which works on 21V DC and draws 3A maximum current. I need to get it tested to IEC 61000-4-4 and 61000-4-5 standards which are surge immunity tests. I use a UL certified switch mode ...
3
votes
3answers
319 views

TVS specification understanding

I have some questions regarding Transient Voltage Suppressors (TVS). The specific datasheet I'm referring to is this, from 1SMB22AT3G. Here is some of its specs: \$V = 22V\$ \$V_c = 35.5V\$ ...
3
votes
2answers
773 views

How to suppress current spikes in transistor feedback loop

I am trying to pulse a load with a small constant current pulse (2mA @ 500us). The load does unfortunately have an unknown capacitance in the range 10nF - 1uF, parallel with an unknown resistance ...
1
vote
2answers
237 views

Surge suppression for electric motor

I have a 4.2W 12V electric water pump connected in series with a water float switch as a sump pump, powered by a 1A 12V DC power brick. The switch has a maximum switching voltage rating of 100V. ...
2
votes
2answers
737 views

Transient Voltage Suppressor (TVS) Diode Array

I am having a hard time understanding this logic. Please bare with me if my question is very basic. I would appreciate if someone can explain what is happening? If I look into any typical TVS IC data ...
5
votes
1answer
247 views

Current-sense for NES/SNES gamepad detection - getting a voltage spike

I'm in the process of designing a wireless controller receiver for the NES/SNES game consoles. My wireless receiver consists of a bluetooth module and an AVR microcontroller, with the microcontroller ...
4
votes
2answers
434 views

Regarding ESD diode's architecture

I need one clarification regarding ESD,EFT and SUrge protectors. Different manufacturers have architectures of diodes+Zenar diode combinations for different protection levels for different interfaces. ...
1
vote
2answers
535 views

Varistor S10K30 for 24-40VDC input?

I was put in charge of redesigning a motor control circuit which accepts 24-40V DC on its input. As a side note: As far as i know, the existing circuit has been working fine for several years. The ...
7
votes
1answer
689 views

Help tame turn-on transient

I'm working on a dual headphone amplifier. I've discovered that it has a pretty bad turn-on transient that results in a loud pop if headphones are plugged into the amplifier when it is turned on. ...
5
votes
3answers
1k views

How to properly snub transient spikes from a transformer and prevent switch mode power supply burn out

I've received a failed switch-mode DC-DC step down converter (part# LTC3631 from Linear). This circuit was driven by a 24VAC transformer which is rectified on the circuit: simulate this ...
16
votes
2answers
5k views

How to decide between a TVS or Zener diode for overvoltage protection?

I'll leave my specific circuit out of this for a more broad question: What criteria does one use when deciding whether to use a Zener diode or a transient voltage suppressor, for overvoltage ...
9
votes
2answers
5k views

What are bidirectional Zener diodes used for in DC transient protection?

I often see two zeners (in opposition to each other) being placed across the power supply rails. I don't understand why that is necessary. For example, if I have a 16V Zener diode and a 12V power ...
9
votes
2answers
2k views

Flyback diodes issues and pull-in & hold current issues in this Relay circuit

Although this may be a basic question but I'm still struggling with it. In this schematic, two zener diodes D1 and D2 are connected back-to back across relay coil L1. The BVds = -30V for Q1. Can I use ...
4
votes
1answer
175 views

How does a high voltage condition break down a semiconductor?

I have TVS diode in parallel with circuitry for ESD/lightening/transient voltage protection. Say I receive an over-voltage condition which is beyond the specifications of the part, what happens ...
4
votes
2answers
2k views

Long supply line and capacitor to prevent voltage drop

I have a 30 feet line with DC supply 12 V. A motor on the end draws about 0.5 Amps initially (100 ms). It's logic shuts down because of the line's voltage drop caused by inrush current. A capacitor of ...
16
votes
3answers
9k views

How to limit inrush current?

I'm designing a device powered from USB. The device uses FTDI FT2232 chip for USB connection. Upon a command from a computer FT2232 chip should enable power via a MOSFET switch to rest of the circuit. ...
3
votes
2answers
381 views

Are transient suppression diodes necessary for a battery powered system?

I've seen on designs where there is a TVS transient suppression diode on the voltage supply. For example, when the voltage supply is say a wall plug. However, are such diodes really necessary in a ...