Electronics Design Laboratory Lecture #2 Fall 2013

Electronics Design Laboratory Lecture #2 Fall 2014

ECEN 2270 1 Electronics Design Laboratory

Lab 1: Introduction • Objectives

– Develop laboratory and circuit design skills and techniques,

perform simulations, prototyping, testing and debugging

• Part A: Laboratory equipment

– Become familiar with electronic laboratory equipment

• Part B: Reverse engineering:

circuit schematics and prototypes

– Gain experience working with

electronic components, circuit

schematics, prototyping boards,

and simulation

Electronics Design Laboratory 2 ECEN 2270

Proto-board


• Prototype boards are useful for quickly implementing ‘simple’ circuits

• Provides a stable foundation for constructing circuits

• Middle divide is spaced correctly for many common integrated circuits

• Vertical side columns for power/ground • Integrated Circuits fit across middle gap

GOOD! clean and simple. No long loops and a clean layout.

BAD! Stray wires, long loops, messy setup. This would be a struggle to debug!

Example Proto-Board Internal Connections

A badly implemented protoboard circuit can take days to debug. Spend the time to do things well initially… it will save you time in the long run!

Components, Schematics, and Breadboard Wiring


• A circuit is a collection of interconnected electrical components (devices)

– Circuits are loops, such that charge (electrons) can flow continuously without beginning or end

• To specify and document electrical circuits, standardized symbols are used for the devices and the wires that interconnect them.

• Components typically encountered in electronic circuits include

– Batteries

– Resistors

– Capacitors

– Inductors

– Diodes

– Transistors

– Op-Amps

– Various integrated circuits, etc.

– Ideal Sources and Sinks

Symbols vary, sometimes describe physical shape and sometimes describe IC function

Resistors


Characteristics: • Resistance

• Linear relationship between voltage and current

• Tolerance • 1%, 5%, and 10% are Common

• Power rating • ¼ and ½ most common. Larger

‘power resistors’ available for kW and higher ratings.

• Other: temperature dependence, … Example: ( 4 7 ) * 100k = 4.7 MW, +/-5%

Characteristics: • Capacitance

• 𝒊 𝒕 = 𝑪𝒅𝒗(𝒕)

𝒅𝒕

• Integrates currents • Types:

• electrolytic

• ceramic, film, …

• Important Parameters • Voltage rating • Tolerance • Equivalent series

resistance (ESR)

Ceramic and Other Caps: - Two digits assumes pF (x10-12)

- Three digits assumes pF with

an additional multiplier

Capacitors


47 mF, 35VMAX negative lead is on the left

22 (assume x10-12) = 22pF

Electrolytic Caps: - Polarity Sensitive devices! - Value Written on Side - Long lead/Color

Stripe/Minus Sign denotes the negative terminal

10 x 103 (assume x10-12) = 10nF

A

C C

A

Diodes


Characteristics: • Voltage, current and power ratings • V(I) characteristic, forward voltage drop • Many other: long data sheets

Integrated Circuits (ICs)

For most Integrated Circuits… • A dot/divot/chip/etc indicates pin 1. • Most ICs number pins top to bottom left then right.

Not all do this! Check with every chip! • Part number may or may not be on top of chip • Questions about a particular IC can almost always be

answered by reading the datasheet. • Googling for the part number, or using a site like

digikey.com are good ways to find data sheets. • If you know the part number, you can find the

datasheet and answer any questions yourself.

Rules of Drawing Circuit Diagrams (aka Schematics)

• Diagram must be complete and informative: – All components and all connections must be shown

– Components

• Use standard, commonly accepted component symbols

• Must have names, use standard naming conventions (e.g. R1, C1, …)

• Show values using appropriate units (e.g. W, kW, MW, mF, nF, pF), or part numbers

• Placement: horizontal or vertical

– Input and output ports, and connecting wires

• Straight horizontal or vertical lines, do not cross components or text labels

• Connections


• All inputs, outputs, and other relevant voltages and currents must have names (use standard naming conventions, e.g., V1, I1, vout, iout)

– Other miscellaneous info, e.g. comments, author, date, revision, …

Wires that cross, but are not connected(use as few of these as possible)

Good BetterNotgoodGood

Connected wires

Rules of Drawing Circuit Diagrams (aka Schematics)

• Follow standard layout – Power supply wires

• Positive supply voltage (e.g. +VCC, +VDD) is a horizontal line on top

• Ground is a horizontal line at the bottom, or use the ground symbol

• Negative supply voltage (e.g. –VEE, -VSS) is a bottom horizontal line

– Logical direction of signal flow, e.g. inputs on the left, outputs on the right


+VCC

+

_

vinvout

+

_

Example 1: op-amp amplifier Task: draw circuit diagram of an op-amp amplifier with a gain A = vout/vin = +2.

The amplifier has a single dc supply voltage VCC = 12 V



Incomplete: missing supplies

Incomplete: R2 value? Non-standard

R1 value

Weird op-amp orientation Incomplete: input & output not labeled, components not labeled, values unknown

Where is ground?

Not straight

?

Upside-down ground and supply

Weird placement of R1, R2

Op-amp not labeled

C1 value? Unnecessary wire crossings Some do not like these R symbols

Wrong circuit

Example 1: op-amp amplifier


Inputs on the left

Outputs on the right

Ground on the bottom

Voltage Supply near the top

Text labels used to help group components

All components have names and values

Wire routed with as few overlaps as possible

Example 1: simulation results


Simulating Circuits - LTSpice • LTSpice is on of many ‘Simulation Programs with Integrated Circuit Emphasis’ (SPICE)

• Useful for complex circuit simulation. Test before you build!

• Many manufacturers pride spice models for their devices


Electronics Design Laboratory Lecture #2 Fall 2013

Documents

Transcript of Electronics Design Laboratory Lecture #2 Fall 2013