1. EDGE™ prepared by Prof. George Slack (EE) Copyright © 2006 Rochester Institute of Technology All rights reserved. Noise Immunity Transients and ESD Practical Design Considerations

2. EDGE™ noise immunity Circuit noise immunity is the ability of a device or component to operate in the presence of noise disturbance. Electro Static Discharge is the sudden discharge (i.e. transients, surge). To the circuit, this is a rapid high voltage, low current situation.

3. EDGE™ When is Noise Immunity design needed? Senior Design I – –Paper Design wks 1-8 Senior Design II – –Prototype device testing wks 1- 3. – –Pre-integration testing with lab equipment DUT (device under test). Wks 3- 6

4. EDGE™ Where does noise get into electronics? 6.4.1 Sources *6.4.1 Sources * through ground connections and loopsthrough ground connections and loops through power supply connectionsthrough power supply connections through signal inputsthrough signal inputs through inadvertent ESDthrough inadvertent ESD –(human touch, lightning) through Inductive devices (motors)through Inductive devices (motors) Electronic Instrumentation Design, Kim R. FowlerElectronic Instrumentation Design, Kim R. Fowler

5. EDGE™ How does noise get into electronics? How does noise get into electronics? Energy Coupling (Conductive, Inductive, Capacitive) EMI - Current surgesEMI - Current surges (ElectroMagnetic Interference) An electrical disturbance in a system due to natural phenomena, low-frequency waves from electromechanical devices or high-frequency waves (RFI) from chips and other electronic devices. Allowable limits are governed by the FCC.  RFI – high impedance devices requiring very limited current. (Radio Frequency Interference) High-frequency electromagnetic waves that emanate from electronic devices such as chips. If the source is sufficiently strong this can enter your circuit.

6. EDGE™ ESD and unwanted signals Fatal to Electronics:Fatal to Electronics: Inadvertent user misuse.Inadvertent user misuse. Extreme cases of user abuse and solutions:Extreme cases of user abuse and solutions: –Bridge to block reverse polarity, –Schottky diode: very fast switching times and low forward voltage drop. As low as 0.15 volts for low ma applications. –Zener diode across the input. –Circuit breaker – GFI

7. EDGE™ Bare exposure to a CMOS gate Reduce Transients Protect from? Misuse during debug and testing.Misuse during debug and testing. ESD and reverse polarityESD and reverse polarity –Solution: Diode circuits to protect against reduce transientsreduce transients –Component Specification Sheets –Solution: Low pass filter

8. EDGE™ Polarity Protection + Input Port – (+) (–)(–) + Input Port – 1N5822 or 1N5817 1N4001 Schottky diode see 7.4.1 page 238, MOSFET solution

9. EDGE™ Over-voltage Protection Fuse 1N5339 (5.6V for a 5.0V input) + input port – (+) (–)(–) Zener diode

10. EDGE™ Over-voltage Protection for Digital Inputs

11. EDGE™ Minimize Bandwith One solution: Lowpass Filter

12. EDGE™ 1. 1.If considering various output devices, review various manufactures specification sheets. 2. 2.Current (i.e. CMOS versus TTL ). 3. 3.Control Voltage (Vdd vary from 1.5 VDC to 12 VDC typically) 4. 4.Needed minimum Signal Transient Response. 5. 5.RLC loads (dangerous current and voltage spikes) 6. 6.Apply to Thevenin Equivalent Circuits – –Source electronics – –Device being driven Knowing Your Design Specification

13. EDGE™ Harness -Twisted Pair When purchasing harness cable: Unshielded Twisted Pair (UTP)Unshielded Twisted Pair (UTP) Shielded Twisted Pair (STP)Shielded Twisted Pair (STP) Study the manufacturer’s Specification to match to your needs. Practical Design Considerations http://www.cirris.com/testing/twisted_pair/twist.html http://www.cirris.com/testing/twisted_pair/twist.html

14. EDGE™ Harness Signal Response Design Considerations: data rate, distance, noise, parasitic capacitance, reflections. 1.Frequency Response/ Rise Time needs –DC to 100 khz Open Wire –DC to 40 MB/s Ribbon Cable (less than 3’) SCSI, SPI-3 applicationsSCSI, SPI-3 applications http://www.csee.umbc.edu/~plusquel/650/slides/ribbon_cables.pdfhttp://www.csee.umbc.edu/~plusquel/650/slides/ribbon_cables.pdfhttp://www.csee.umbc.edu/~plusquel/650/slides/ribbon_cables.pdf –DC to 300 mhz Twisted Pair - unshielded, ribbon –DC to 100/1000 MB/s 10/ 100/ 1000 BaseT ethernet Cat 5 minimum spec. RJ45 connector. –Coax, VHF 3000 megahz (scope probe, cable TV) attenuation, reflectance, Cable TV, Rf http://www.netspec.com/helpdesk/wiredoc.htmlhttp://www.netspec.com/helpdesk/wiredoc.html –DC to 4 gigahz Fiber Optics

15. EDGE™ Harness -Twisted Pair What is does: Cancels out crosstalk from neighboring wires and electromagnetic interference from external sources

16. EDGE™ CMOS characteristics Print out the specification sheets. 1 uA input? Not sure? Get the spec sheet!...1 uA input? Not sure? Get the spec sheet!... Draw the equivalent circuit for each internal pin. That is, CMOS versus TTL input impedance, output is pull-up or pull-down circuit, current limiting resistor value.Draw the equivalent circuit for each internal pin. That is, CMOS versus TTL input impedance, output is pull-up or pull-down circuit, current limiting resistor value. CMOS inputs have very high input impedance which is good for low power consumption for well protected electronics but susceptible to misuse when connecting to the outside world.CMOS inputs have very high input impedance which is good for low power consumption for well protected electronics but susceptible to misuse when connecting to the outside world.

17. EDGE™ Isolating Noise Analog and Digital Optocoupler /Optoisolators Somewhat expensive ($1/ channel) but good isolation.Analog and Digital Optocoupler /Optoisolators Somewhat expensive ($1/ channel) but good isolation. –an electronic device that uses optics to transfer a signal while keeping the receiving and transmitting circuits electrically isolated http://www.analog.com (Analog Devices)http://www.analog.com (Analog Devices)http://www.analog.com http://www.optoinc.com/http://www.optoinc.com/http://www.optoinc.com/ http://www.optoinc.com/optocouplers1.htmlhttp://www.optoinc.com/optocouplers1.htmlhttp://www.optoinc.com/optocouplers1.html Power connection.Power connection. What does not work?What does not work? –Fuses tipically are ineffective since a fuse is too slow to stop ESD current but good for harness shortcircuit. ShieldingShielding Fiber OpticsFiber Optics –When higher speed data is needed.

18. EDGE™ Isolators Analog Devices, Isolators http://www.analog.com/en/subCat/0,2879,767%255F827%255F0%255F%255F 0%255F,00.htmlAnalog Devices, Isolators http://www.analog.com/en/subCat/0,2879,767%255F827%255F0%255F%255F 0%255F,00.html http://www.analog.com/en/subCat/0,2879,767%255F827%255F0%255F%255F 0%255F,00.html http://www.analog.com/en/subCat/0,2879,767%255F827%255F0%255F%255F 0%255F,00.html Isolators: http://www.analog.com/en/prod/0,2877,ADuM2401,00.htmlIsolators: http://www.analog.com/en/prod/0,2877,ADuM2401,00.html http://www.analog.com/en/prod/0,2877,ADuM2401,00.html

19. EDGE™ components and spec sheets http://www.electronicstalk.com/guides/short-circuit- protection.html http://www.maxim- ic.com/appnotes.cfm/appnote_number/38 http://www.onsemi.com/PowerSolutions/taxonomy.do?id=29 8http://www.onsemi.com/PowerSolutions/taxonomy.do?id=29 8 EMI RFI http://www.edn.com/article/CA326921.html http://www.bussmann.com/library/techspec/TechSpec19_s up.pdf#search=%22short%20circuit%20protection%22 http://www.elecdesign.com/Articles/Index.cfm?AD=1&Artic leID=5195http://www.elecdesign.com/Articles/Index.cfm?AD=1&Artic leID=5195 UL 489 and UL1077 standards