1/09/2013
Embedded Systems Design ELEN90066
Lecture 11 Finding Components
David Jahshan
Notes from last lecture
• Have some high level understanding of the following:
– High Speed Multilayer PCBs
– PCB capacitors, inductors and antennas
– Termination resistors to stop reflections
– Impedance of the track can be controlled by the thickness of the track
– Pin swapping to improve routing
– High Current PCB tracks
– Auto routing
Possible Exam Questions
• Why might you have a big ground plane and vcc plane on a multilayer board?
• Why would you terminate a PCB track with a resistor?
• Why might you swap general IO pins around on a microcontroller?
Identifying Components
• Identification numbers are tricky and require a bit of getting user to.
• Example 74 series
• 74AHC30 is similar to 74LS30DRB which is
similar to 74C30. The key is 74 and 30
• The ATMEGA16 is the root family, the ATMEGA16L is the sub family
Different Manufacturers
• Different manufacturers, different naming conventions
• Can be somewhat confusing
• Need to be very careful of different footprints
• Some names are trademarks:
– TWI (Two wire interface) also known as I2C (Inter IC Communications) which is a registered trademark for of Phillips.
Different IC Packaging
• DIPDualInlinePackage
• QuadFlatPackage
• PQFPPlastic,TQFPThin,LQFTLowprofile • PGAPinGridArray
• PLCCPlasticLeadChipCarrier
• BGABallGridArray
• LGALandGridArray
• SOICSmallOutlineIC,SOSOP
1
1/09/2013
Different Discrete IC’s Packaging
• Transistors and Power regulators – SOT-23
– SOT-93
– TO-3
– TO-220
– Many More
Different Component Packaging
• Resistors, capacitors, inductors, diodes – DO-15
– SIL
– MCF
– 0603
– 0805
– 1206
– Many More
Images in previous 3 slides courtesy of Wikimedia Commons
Other Considerations
• Cost
– Some packages are easier to manufacture
– Some packages can be plugged in and unplugged
• Availability
– What is available at time of production – PCB with 2 footprints eg qfp and pqfp
Design Decisions
• Does the component do what I need it to do
• Is the component available
• Will the component remain available
• How much does the component cost
• Does the component have testing facilities
• Do we have the manufacturing facilities to use this component
Sourcing Components
• DigikeylargeUSdistributer – www.digikey.com
• MouserlargeUSdistributer – www.mouser.com
• Element14largedistributerAustraliabranch – http://au.element14.com/
• RSlargedistributerAustralianbranch – http://australia.rs-online.com/web/
• JaycarLocalretailersmallrange – http://www.jaycar.com.au/
• Altronicslocalretailersmallrange – http://www.altronics.com.au/
So how do we find components
• Let us use the parts for this project
– Decoupling capacitors 100nF
– Capacitors are in uF and pF so what is 100nF?
• 0.1uF – Resistors
– Diodes
– MOSFETs
– Microcontrollers
2
1/09/2013
Next Lecture
• Start looking at the internal workings of a microcontroller.
– ALU and registers – RAM access
– IO Pins
3