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Diodes Zener diodes Electronics Diodes Terry Sturtevant Wilfrid Laurier University September 9, 2015 Terry Sturtevant Electronics Diodes
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Transcript of Electronics Diodes - denethor.wlu.cadenethor.wlu.ca/pc320/lectures/diodebeam.pdf · Terry...

  • DiodesZener diodes

    ElectronicsDiodes

    Terry Sturtevant

    Wilfrid Laurier University

    September 9, 2015

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Diodean electronic device which passes current in one direction only

    diode starts to allow current in the forward direction when thevoltage reaches around 0.6VIf the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Diodean electronic device which passes current in one direction onlydiode starts to allow current in the forward direction when thevoltage reaches around 0.6V

    If the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Diodean electronic device which passes current in one direction onlydiode starts to allow current in the forward direction when thevoltage reaches around 0.6VIf the voltage gets high enough in the reverse direction, thediode will conduct; “reverse breakdown voltage”

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Negative pressure; no flow possible

    ��

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    No pressure; resistance to flow is large

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Small pressure; resistance to flow decreases

    -

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Medium pressure; resistance to flow still decreasing

    --

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    High pressure; resistance to flow small

    ---

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Very high pressure; resistance almost zero

    ----

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    + -

    Diode symbol and physical appearance

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    + -

    anode

    Diode symbol and physical appearance

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    + -

    anode cathode

    Diode symbol and physical appearance

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Signal diodes (one type)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Signal diodes (another type)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Power diodes (one type)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Power diodes (another type)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    “off”

    V . 0.7?

    “off”

    I small; changes slowly

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    “off”

    V ≈ 0.7

    6 “on”

    I large; almost independent of V

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    forward biasreversebreakdown

    |V | < Vz

    6

    I small; changes slowly

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    forward biasreversebreakdown

    Vz 6

    I large; almost independent of V

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    VD ≈ 0.7

    Vo ≈ Vs − 0.7(assuming Vs & 0.7)

    Vs

    Forward biased diode in a voltage divider

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    VD ≈ 0.7

    Vo ≈ 0.7(assuming Vs & 0.7)

    Vs

    Forward biased diode in a voltage divider

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Vo ≈ Vs(assuming Vs > 0)

    I ≈ 0

    Vs

    Reverse biased diode in a voltage divider

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Vo ≈ 0(assuming Vs > 0)

    I ≈ 0

    Vs

    Reverse biased diode in a voltage divider

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    One common use of diodes is for rectification, by putting diodesin a bridge circuit.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Here’s the basic bridge.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    B A

    - +

    The output is taken between A and B.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    B A

    - +

    +

    -

    For one half of the cycle, these two diodes shown in green are forwardbiased, so they’re on. (The others are off.)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    B A

    - +

    -

    +

    For the other half of the cycle, the other two diodes shown in greenare forward biased, so they’re on. (The others are off.)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    For both parts of the cycle, A is positive relative to B.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    LEDs are a special case; they light up above a certain voltage. Thevoltage depends on the colour.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    anode (+) cathode (-)

    The LED lights up when current flows from the anode to thecathode..

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    You must use a resistor to limit the current.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    You must use a resistor to limit the current.Without a resistor, the LED will probably be destroyed.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    The resistor can go before or after the LED.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    The resistor can go before or after the LED.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Reverse-biased, the LED won’t light up.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes LEDs

    Reverse-biased, the LED won’t light up.

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    VoutR

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    VoutR

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    VoutR

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    Vout

    R

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    VoutR

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Zener diodes

    One of the ways to produce a stable reference voltage, such as foran ADC or a DAC, is to use a Zener diode.

    Vin

    VoutR

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Parameters

    Zener voltagerequired currenttemperature sensitivityvariation with current (ac resistance)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Parameters

    Zener voltage

    required currenttemperature sensitivityvariation with current (ac resistance)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Parameters

    Zener voltagerequired current

    temperature sensitivityvariation with current (ac resistance)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Parameters

    Zener voltagerequired currenttemperature sensitivity

    variation with current (ac resistance)

    Terry Sturtevant Electronics Diodes

  • DiodesZener diodes Parameters

    Parameters

    Zener voltagerequired currenttemperature sensitivityvariation with current (ac resistance)

    Terry Sturtevant Electronics Diodes

    DiodesLEDs

    Zener diodesParameters