Output Driver Circuit Practical Design Considerations Output driver

Output Driver Circuit Practical Design Considerations Output driver circuit is the electronics between the low power control electronics and the output device. prepared by Prof. George Slack (EE) Copyright © 2006 Rochester Institute of Technology All rights reserved. EDGE™

When is this needed? • Senior Design I – Paper Design wks 1 -8 – Lab feasibility "Fail Often, Fail Fast, Fail Cheap" wks 3 -7 • (i. e. evaluation, characterization, shortfalls) • Senior Design II – Prototype device testing wks 1 - 3. – Pre-integration testing with lab equipment DUT (device under test). Wks 3 - 6 EDGE™

Driver Circuit Interface • Input: Logic/ Microcontroller to input of electronics drivers. • Driver Circuit: (typically voltage to voltage, voltage to current. ) • Output: Driver device. – – Motors, Linear Actuators Solenoids Storage Capacitors HVPS EDGE™

What are the key considerations and tools? • Bandwidth, frequency response, rf to dc • Impedance matching • • Low Voltage to High Current Low Voltage to High Voltage Low Current to High Current Low to Current to High Voltage • Circuit 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. EDGE™

Applying Specification Needs 1. If considering various output devices, review various manufactures specification sheets. 2. Current (i. e. CMOS versus TTL ) needs, sink, source or both Vdd/Vcc. 3. Control Voltage (Vdd vary from 1. 5 VDC to 12 VDC typically) 4. Frequency Response. 5. Heat and EMI Noise considerations 6. RLC loads (& potential for dangerous current and voltage spikes) 7. Apply to Thevenin Equivalent Circuits – Source electronics – Device being driven EDGE™

Types of Drive Components • • • Transistors: Single stage and Darlington up. Op Amps JFETs MOS FET IGBT DC to AC inverters (hybrid cars, mass transit) • Optical Switching devices EDGE™

Example of Driver Circuit • Input: PIC 18 F 2455 Micro. Controller – See attached pdf to the right. • Driver Circuit – Opto 22 ODC 5 – See attached pdf to the right. • Output Device – 2. 5 a, 50 vdc Inductive Load EDGE™

Specific Applications: • • • H bridge – DC Motors Optical Isolators- Power Supply Separation Optical Drivers Fiber Optics and Fiber Optics I/0 Devices DC to DC converters – voltage boasting/ ± polarity – current boasting EDGE™

H Bridge Considerations • Motors or whenever you need to direct current. • Introduction to H bridge operation: – http: //www. dprg. org/tutorials/1998 -04 a/ • Designing an H-Bridge and PWM Circuits and Code – http: //www. learn-c. com/experiment 7. 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. • Design Needs: Inductive loads and protection diode. EDGE™

components and spec sheets • Manufacturer’s Home Pages • http: //www. findchips. com/ • Google • http: //cmpmedia. globalspec. com/ • Suppliers: Digi. Key, Mouser and Allied offer good on-line spec sheets. • RIT Library services • microcontroller evaluation kits http: //www. esacademy. com/automation/ faq/primer/6. htm EDGE™

Rochester source • 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 form) EDGE™