Safety / Protection Circuits, Page 8
Safety / Protection:  #-B     C-D     E-K    L-N     O-R      S      T-V
Last Updated on: Wednesday, November 29, 2017 05:39 AM

Output Power Limiter -  Just the thing if you want to limit amplifier power to something "sensible"… [Rod Elliott (ESP)]

Over Voltage Protection -  Safety devices like fuses provide protection against excess current, but do nothing for transients and short duration spikes of high voltahe on the power supply lines.This circuit uses the "crowbar" method and provides fast protection against transient voltage spikes… [Andy Collison]

Over-/Under-Voltage Protection of Electrical Appliances -  This circuit protects refrigerators as well as other appliances from over and under-voltage. Operational amplifier IC LM324 (IC2) is used here as a comparator. IC LM324 consists of four operational amplifiers, of which only two operational amplifiers (N1 and N2) are used in the circuit. … [© EFY Enterprises Pvt. Ltd. All rights reserved.]

Over-/Under-Voltage Protection of Electrical Appliances -  This circuit protects refrigerators as well as other appliances from over and under-voltage. Operational amplifier IC LM324 (IC2) is used here as a comparator.… [C.H. VITHALANI]

Overcurrent and Undervoltage Battery Fault Protection -  The LT6109 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and two comparators. Two versions of the LT6109 are available. The LT6109-1 has the comparators connected in opposing polarity and the LT6109-2 has the comparators connected in the same…  [Linear Technology App Note, Sep 7th 2011]

Overcurrent Battery Fault Protection -  The LT6108 is a complete high side current sense device that incorporates a precision current sense amplifier, an integrated voltage reference and a comparator. Two versions of the LT6108 are available. The LT6108-1 has a latching comparator and the LT6108-2 has a non-latching comparator. In addition, the current sense amplifier…  [Linear Technology App Note, Sep 7th 2011]

Overload & Reverse Current Circuitry Protects Battery & Load -  03/01/96 EDN Design Idea   Battery-operated equipment is prone to the consequences of backward-installed batteries, accidental short circuits, and other careless use. The effects of a reversed battery are critical. Unfortunately, it's difficult to guard ag… [by Dana Davis, Maxim Integrated Products]

Overvoltage Circuit -  A simple 5 Volt regulated PSU featuring overvoltage protection.… [Andy Collison]

OverVoltage Protection for LM317 -  This circuit is a modified version of an original interface on QSL Net. It is a fully isolated interface allowing computer control of the Trio/Kenwood R5000 receiver. Separate software is needed to control the receiver.… [submitted by Adam]

Over-Voltage Protector -  This circuit protects your television as well as other electrical appliances from over-voltage. It uses operational amplifier μA741 (IC1) as a comparator. The unregulated power supply is connected to resistor R3 and preset VR1 through resistor R2. Zener diode ZD1 provides reference voltage of 5.1V to the inverting input (pin 2) of IC1. … [© EFY Enterprises Pvt. Ltd. All rights reserved.]

Overvoltage Regulator with 250V Surge Protection -  The LT4363 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, such as load dump in vehicles, by controlling the gate of an external N-channel MOSFET. The output is limited to a safe value allowing the loads to continue functioning. The LT4363 also monitors the voltage… [Linear Technology App Note, Jan 16th 2012]

Overvoltage Regulator with Low Battery Detection and Output Keep Alive During Shutdown -  The LT4356 surge stopper protects loads from high voltage transients. It regulates the output during an overvoltage event, such as load dump in automobiles, by controlling the gate of an external N-channel MOSFET. The output is limited to a safe value thereby allowing the loads to continue functioning. The LT4356 also monitors… [Linear Technology App Note, Apr 26th 2010]

PIC Speaker Protection -  This doesn't replace P33, but it is possibly the ultimate speaker protection.… [Rod Elliott (ESP)]

Polarity Protector Outperforms Schottky Diodes -  02/06/03  EDN Design Idea   Oscillating output improves system security - The polarity-protection circuit in Figure 1 is a high-performance alternative to the usual series diode (often Schottky]. The circuit incurs a much lower voltage drop than even the best S… [by Mike Hovenga, BAE Systems, Austin, TX]

Power Supply Transient Protection for MNA & VNA Amplifiers -  AN-60-027 Application Note MiniCircuits.com…

Power-line outage flashes red alert -  06/13/02  EDN Design Idea   This Design Idea   expands on a circuit in a previous one to configure a power-outage detector with a flashing alarm (Figure 1, Reference 1]. The circuit plugs into a mains outlet and uses trickle-charged nickel-cadmium batteries. The … [by Vasiliy Borodai, Zaporozhje, Ukraine]

Power-Supply Decoupler Protects Your UUT -  05/10/12 EDN Design Idea   Detect and shutdown reverse polarity or overvoltage before damage occurs. You can install the bench-top accessory in Figure 1 between a variable-voltage bench power supply and a breadboard or UUT (unit under test) to protect against accidental overvoltage and reverse polarity. It draws its power from the supply and pulses a 5V, two-coil latching relay to interrupt power to the load under abnormal conditions.… [by Raju Baddi, Tata Institute of Fundamental Research, Pune, India]

Power-Supply Failure Alarm -  …

Power-supply interrupter fights ESD-induced device latch-up -  07/21/05  EDN Design Idea   Optoisolator-based circuit protects digital components from ESD… [by Emerson Segura, Lifescale Global Diagnostics Inc, Toronto, ON, Canada]

Prevent Deep Discharge of Battery -  09/26/96 EDN Design Idea   NOTEPage includes several designs, scroll to find this onemCs such as the 8051 and 8096 and UARTs such as the 82510 provide hardware support for a multiprocessor asynchronous serial-communication protocol (MicroLan].This featu… [by Rolando Herrero, Instituto Tecnologico de Buenos Aires, Argentina]

Prevent processor latch-up -  03/04/99 EDN Design Idea   (contains several designs, scroll to find this one)   The circuit in Figure 1 uses a Dallas Semiconductor DS1820 one-wire digital thermometer in a multipoint temperature-measurement system. The DS1820 sensor allows distributed temperature measurement and uses only one wire for both data communication and the power supply. You can easily connect the one-wire interface to a µC (in this example, a PIC16C63). The application accommodates as many as 16 DS1820 sensors in a 100m-long network, dubbed MicroLAN by Dallas.… [by Michal Ko[bylecki and Wojda Wlodzimierz, MK Design, Warsaw, Poland]

Prevention & Control of Electrostatic Discharge ESD -  AN-40-005Application Note MiniCircuits.com…

Prevents Deep Discharge of Battery -  09/26/96 EDN Design Idea   NOTEPage includes several designs, scroll to find this onemCs such as the 8051 and 8096 and UARTs such as the 82510 provide hardware support for a multiprocessor asynchronous serial-communication protocol (MicroLan].This featu… [by Rolando Herrero, Instituto Tecnologico de Buenos Aires, Argentina]

Protect Against AC-Line Disturbances -  07/02/98 EDN Design Idea   (File has several circuits, please scroll to find this one.) TThe circuit in Figure 1 protects the ac line against disturbances. It operates by switching off the power supply upon detection of undervoltage or overvoltage conditions. The circuit thus protects refrigerators, washing machines, air conditioners, and other appliances from permanent damage that could accrue from working outside their specified power requirements. The problem assumes particular importance in underdeveloped countries or regions where the ac-supply network is incorrectly configured, and the voltage frequently drops to levels low enough to damage coils and motors. When the ac-line voltage returns to its nominal level, the circuit automatically resets a switch and reconnects the line voltage.… [by Basilio Simoes, ISA, Coimbra, Portugal]

Protect Bu from 5v Swings -  11/14/02  EDN Design Idea   The circuit in Figure 1 automatically detects voltage and protects a bus, such as a 3.3V-limited PCI bus, from 5V signal-level swings. You can also use the circuit to determine bus-voltage swings within one bus-cycle for setting ap… [by Said Jackson, Equator Technologies Inc, Campbell, CA]

Protect Computer's Input -  05/26/94 EDN Design Idea   The circuit in Fig 1 performs input protection, level translation, isolation, and debouncing. The circuit allowed the output of a relay driver to connect to a computer even though the relay driver delivered a voltage as … [by Ang Tzu Seng, Halliburton Drilling Systems, Singapore]

Protect FPGA from Killer Spikes -  04/23/98 EDN Design Idea   A project using Xilinx FPGAs brought an interesting problem to light. When you turn on the board, one FPGA in three succumbs to this problem. A lot of frustration and testing uncovered a negative-going spike (Figure 1) in the 5V li… [by Nelson Nguyen, Anritsu Corp, Morgan Hill, CA]

Protect Power-LED Strings from Overcurrent -  06/23/11  EDN Design Idea   Add diodes and a transistor to a current mirror to prevent LED damage. A common method for driving multiple power LEDs is through two parallel strings. This inexpensive and less critical driver circuit can provide a lower voltage. However, the driver circuit must deliver twice the current of other methods and needs a circuit that halves the current in the two strings, regardless of the LEDs’ forward voltages. The LEDs’ forward-voltage tolerance is as high as 20%, and the voltages change with LED temperature and aging.… [by Luca Bruno, ITIS Hensemberger Monza, Lissone, Italy]

Protect system from overheating -  11/08/01  EDN Design Idea   The two-chip circuit in Figure 1 provides fan control and overtemperature warning and shutdown signals to protect systems from excessive heat. The circuit monitors the temperature of the pc board and the die temperature of a CPU, an… [by Kerry Lacanette, Maxim Integrated Products, Sunnyvale, CA]

Protected 1A Automotive Solenoid Driver with Overvoltage Shutdown -  The LT1910 is a high side gate driver that allows the use of low cost N-channel power MOSFETs for high side switching applications. It contains a completely self-contained charge pump to fully enhance an N-channel MOSFET switch with no external components.… [Linear Technology App Note, Apr 5th 2010]

Protected Analog Switches -  Analog Devices-Analog Dialogue… [by Ritmanich, Will]

Protecting & Monitoring Hot Swappable Cards in High Availability Systems -  DN360 Design Notes (Linear Technology)…

Protecting a 1/8-Gigawatt Power Supply, or How Do You Make a 2000-A Fuse? -  Analog Devices-Analog Dialogue… [by Evans, Don]

Protecting Data I/O Ports with TVSArrays -  MicroNote 121 from Microsem…

Protecting Data in Serial EEPROMs -  National Semiconductor Application Note …

Protecting Off-Amps -  Analog Devices-Analog Dialogue… [by Ardizzoni, John]

Protecting USB Data I/O Ports -  MicroNote 117 from Microsem…

Protection for your Electrical Appliances -  The simple circuit given here switches off the mains supply to the load as soon as the power trips. The supply can be resumed only by manual intervention. Thus, the supply may be switched on only after it has stabilised… [designer is not given]

Protection from Overvoltage and Overcurrent -  The LTC4361 overvoltage/overcurrent protection controller safeguards 2.5V to 5.5V systems from input supply overvoltage. It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports. The LTC4361 controls an external N-channel MOSFET in series with the… [Linear Technology App Note, Apr 26th 2010]

Protection of USB Port from Overvoltage and Overcurrent -  The LTC4362 monolithic overvoltage/overcurrent protector safeguards 2.5V to 5.5V systems from power supply overvoltage. It is designed for portable devices with multiple power supply options including wall adaptors, car battery adaptors and USB ports.… [Linear Technology App Note, Jul 8th 2011]

Protects Against AC-Line Disturbances -  07/02/98 EDN Design Idea   (File has several circuits, please scroll to find this one.) TThe circuit in Figure 1 protects the ac line against disturbances. It operates by switching off the power supply upon detection of undervoltage or overvoltage conditions. The circuit thus protects refrigerators, washing machines, air conditioners, and other appliances from permanent damage that could accrue from working outside their specified power requirements. The problem assumes particular importance in underdeveloped countries or regions where the ac-supply network is incorrectly configured, and the voltage frequently drops to levels low enough to damage coils and motors. When the ac-line voltage returns to its nominal level, the circuit automatically resets a switch and reconnects the line voltage.… [by Basilio Simoes, ISA, Coimbra, Portugal]

Protects Computer's Input -  05/26/94 EDN Design Idea   The circuit in Fig 1 performs input protection, level translation, isolation, and debouncing. The circuit allowed the output of a relay driver to connect to a computer even though the relay driver delivered a voltage as … [by Ang Tzu Seng, Halliburton Drilling Systems, Singapore]

Protects FPGAS from Killer Spikes -  04/23/98 EDN Design Idea   A project using Xilinx FPGAs brought an interesting problem to light. When you turn on the board, one FPGA in three succumbs to this problem. A lot of frustration and testing uncovered a negative-going spike (Figure 1) in the 5V li… [by Nelson Nguyen, Anritsu Corp, Morgan Hill, CA]

Protects from Battery Polarity Reversal -  This simple circuit can protect a sensitive electronic circuit from an accidental connection of a battery with a reversed polarity.  The N-channel FET connects the electronic device to the battery only when the polarity is correct.  The circuit shown was… [Hobby Circuit designed by David Johnson P.E., 3/09/02]

Protects System from Overheating -  11/08/01  EDN Design Idea   The two-chip circuit in Figure 1 provides fan control and overtemperature warning and shutdown signals to protect systems from excessive heat. The circuit monitors the temperature of the pc board and the die temperature of a CPU, an… [by Kerry Lacanette, Maxim Integrated Products, Sunnyvale, CA]

Provide Flexible Gain Ranges -  06/21/01 EDN Design Idea   Certain designs need a programmable-gain amplifier with a wide gain range and high accuracy and common-mode rejection. Usually, it’s wise to exploit a programmable-gain instrumentation amplifier, such… [by Luo BenCheng, Chinese Academy of Sciences, Beijing, China]

Provide Reverse-Battery Protection -  12/21/00 EDN Design Idea   A universal problem in battery-operated devices is the threat of damage when an end user (never an engineer) inserts the battery backward. You can avoid damage by inserting a single diode or by using a diode-bridge configuration,… [by John Guy, Maxim Integrated Products, Sunnyvale, CA]

Provides Flexible Gain Ranges -  06/21/01 EDN Design Idea   Certain designs need a programmable-gain amplifier with a wide gain range and high accuracy and common-mode rejection. Usually, it’s wise to exploit a programmable-gain instrumentation amplifier, such… [by Luo BenCheng, Chinese Academy of Sciences, Beijing, China]

Provides Reverse-Battery Protection -  12/21/00 EDN Design Idea   A universal problem in battery-operated devices is the threat of damage when an end user (never an engineer) inserts the battery backward. You can avoid damage by inserting a single diode or by using a diode-bridge configuration,… [by John Guy, Maxim Integrated Products, Sunnyvale, CA]

RC-Timed Shutoff Function Uses Op Amp and Momentary Switch -  02/16/12  EDN Design Idea   Battery-operated instrument benefited from auto-power shutdown. A handheld, battery-operated “fiber finder” measures the light escaping from an optical fiber when clamped in a V-shaped block under slight pressure. A pair of photodiodes on each side of the resulting bend compares analog levels to indicate the presence and direction of light travel, and PLL tone decoders indicate the presence of as many as three optical-modulation tones. The idea is to “tag” a fiber with a central-office signal… [by Glen Chenier, Teeter Totter Tree Stuff, Allen, TX]

Replace a Pushbutton Switch with this Infrared Safety Switch -  Using a slotted optical sensor, this circuit can be used as a replacement for a large mushroom pushbutton safety switch… [Hobby Circuit designed by Dave Johnson P.E., 7/11/06]

Reverse-Polarity-Protection Circuit Has No Voltage Drop -  10/20/11  EDN Design Idea   A relay does what semiconductors can’t do.… [by Aruna Rubasinghe-October 20, 2011]

Robust 10MHz reference clock input protection circuit and distributor for RF systems -  07/31/14 LTC Design Note: Design a protected 10MHz reference input without degrading phase noise. Read More... … [by Michel Azarian]