1. EDGE™ Electronic Circuitry between the low power “control electronics” and the input and output devices. prepared by Prof. George Slack (EE) Copyright © 2006 Rochester Institute of Technology All rights reserved. Practical Design I/O Circuits

2. EDGE™ What are the key considerations? Bandwidth, frequency response, rf to dcBandwidth, frequency response, rf to dc Impedance matchingImpedance matching Low Voltage to High CurrentLow Voltage to High Current Low Voltage to High VoltageLow Voltage to High Voltage Low Current to High CurrentLow Current to High Current Low to Current to High VoltageLow to Current to High Voltage Circuit protection electronicsCircuit protection electronics –Surge protection techniques –Debugging can become somewhat frantic with a potential for shorting or over powering. Though electronic devices may be inexpensive, the re-ordering time and re-soldering takes time.

3. EDGE™ When is this needed? Senior Design I – –Phase 3 Detail Design wks 5-11 – –Phase 1 Concept Development wks 3-7 "Fail Often, Fail Fast, Fail Cheap"Lab feasibility "Fail Often, Fail Fast, Fail Cheap" – –(i.e. evaluation, characterization, shortfalls) Senior Design II – –Pre-integration testing with lab equipment DUT (device under test). Wks 3- 6

4. EDGE™ 1. 1.Review various manufactures specification sheets when considering output devices. 2. 2.Timing of data, enables, select lines, etc. 3. 3.Current (i.e. CMOS versus TTL ) needs, sink, source or both Vdd/Vcc 4. 4.Control Voltage (Vdd vary from 1.5 VDC to 12 VDC typically) 5. 5.Frequency Response 6. 6.Heat and EMI Noise 7. 7.Apply to Thevenin Equivalent Circuits – –Source electronics – –Device being driven – –RLC loads (& potential for dangerous current and voltage spikes) Engineering Specifications

5. EDGE™ Engineering Specification Sheets 1. 1.Manufacturer’s Home Pages 2. 2.Suppliers: DigiKey, Mouser and Allied offer good on-line spec sheets 3. 3.http://www.findchips.com/http://www.findchips.com/ 4. 4.http://cmpmedia.globalspec.com/http://cmpmedia.globalspec.com/ 5. 5.Google 6. 6.RIT Library services 7.Microcontroller or device evaluation/ demo kits 8.http://www.esacademy.com/automation /faq/primer/6.htm http://www.esacademy.com/automation /faq/primer/6.htmhttp://www.esacademy.com/automation /faq/primer/6.htm

6. EDGE™ Manufacturer’s 1. Specification Sheets 2. Application Notes Save Hours of design time! Exploit their Design Notes! MicroController Interface needs to protect electronics.MicroController Interface needs to protect electronics. Many Specification Sheets have recommended applications that may apply directly to your design! Use them!Many Specification Sheets have recommended applications that may apply directly to your design! Use them! Example 1. PIC18F2455 Interface considerationsExample 1. PIC18F2455 Interface considerations –See attached pdf. Example 2. Freescale Semiconductor Inc - application schematicExample 2. Freescale Semiconductor Inc - application schematic –Motor Controller MC3PHACVDW

7. EDGE™ Output Circuits Logic: Microcontroller to input of electronics drivers.Logic: Microcontroller to input of electronics drivers. Driver: (voltage to voltage, voltage to current.)Driver: (voltage to voltage, voltage to current.) Device:Device: –Motors, Linear Actuators –Solenoids –Storage Capacitors –HVPS –LEDs –Heaters

8. EDGE™ Types of Drive Components Impedance matching: Op AmpsOp Amps Optical devicesOptical devices Transistors: Single stage and Darlington.Transistors: Single stage and Darlington. JFETsJFETs MOS FETMOS FET IGBT DC to AC inverters (hybrid cars, mass transit)IGBT DC to AC inverters (hybrid cars, mass transit)

9. EDGE™ Specific Applications: H bridge – DC MotorsH bridge – DC Motors Optical Isolators- Power Supply SeparationOptical Isolators- Power Supply Separation Optical DriversOptical Drivers Fiber Optics and Fiber Optics I/0 DevicesFiber Optics and Fiber Optics I/0 Devices DC to DC convertersDC to DC converters –voltage boasting/ ± polarity –current boasting

10. EDGE™ Too often the interfaces are not considered until Senior Design II once integration begins. – –DO IT NOW and order your “debug” supplies along with your other components. Passive Devices: Harnesses (& cables) connectors Test points Discrete LEDs Active Devices: Interface Devices Power On/Off, Reset and Safety Switches Power Reset Switch, Sample Select Switch USB, RS232, Ethernet (may not need the form factor) Accessory power connectors Removable AC power cord Practical Design Considerations

11. EDGE™ Practical Harness Considerations 1. 1.Current, Voltage Needs Gauge of wire, insulation 2. 2.Use and Abuse Connect/ disconnect needs Routing, protecting Mounting, vibration and stability Gold versus Tin; environment, corrosion, current rating Instrumentation quality for long life 3. 3.Color Coding for ease in Debug and future use. As an example; 1. 1.Red Vcc/Vdd 2. 2.Black Grd/ Vss 3. 3.Org for signal 4. 4.Fabricating: Harness board and nails

12. EDGE™ Example of Driver Circuit Driver Circuit – Opto 22 ODC5Driver Circuit – Opto 22 ODC5 –See diagram below for application. –Output Device – 2.5a, 50 vdc Inductive Load

13. EDGE™ BOM misc: Connectors/ Pins Add all needed I/O connectors to your schematic(s). 1. 1.Connect/ disconnect needs – screw terminators, push type 2. 2.Major Manufactures: Amp, Molex 3. 3.Location – –between assemblies – –interface to other projects (collaborate with other teams) – –instrumentation 4. 4.Get crimp compatibility to pin manufacturers (style and gauge). 5. 5.Pins: crimp versus solder 6. 6.Current rating rule of thumb is 10x. i.e. 100 ma purchase 1 amp pins 7. 7.Types; ribbon, D shell, PCB mount

14. EDGE™ H Bridge Considerations Motors or whenever you need to direct current.Motors or whenever you need to direct current. Introduction to H bridge operation:Introduction to H bridge operation: –http://www.dprg.org/tutorials/1998-04a/ http://www.dprg.org/tutorials/1998-04a/ Designing an H-Bridge and PWM Circuits and CodeDesigning an H-Bridge and PWM Circuits and Code –http://www.learn-c.com/experiment7.htm http://www.learn-c.com/experiment7.htm Debugging: Initial reset may close a short circuit or stress on the H bridge. Symptom: Motor shaft may pulse or flinch at power on. May cause immediate failure.Debugging: Initial reset may close a short circuit or stress on the H bridge. Symptom: Motor shaft may pulse or flinch at power on. May cause immediate failure. Design Needs: Inductive loads and protection diode.Design Needs: Inductive loads and protection diode.

15. EDGE™ Rochester source On-line: Digi-Key, Mouser, Allied, …On-line: Digi-Key, Mouser, Allied, … When you want to look at what you are buying:When you want to look at what you are buying: http://www.glenwoodsales.com/ GLENWOOD SALES COMPANY 594 HAGUE STREET ROCHESTER, NEW YORK 14606 USA Tax free with RIT PO (contract Chris Fisher for form)