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Totem pole outputs Open collector outputs Open Collector Advantages CMOS outputs Electronics Logic Gates: Open Collector Output Terry Sturtevant Wilfrid Laurier University October 3, 2018 Terry Sturtevant Electronics Logic Gates: Open Collector Output

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Transcript of Electronics- Logic Gates: Open Collector Outputdenethor.wlu.ca/pc320/lectures/lgcocbeam.pdf ·...

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    ElectronicsLogic Gates: Open Collector Output

    Terry Sturtevant

    Wilfrid Laurier University

    October 3, 2018

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs

    Vcc

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs

    Vcc

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs

    Vcc

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    TTL Totem Pole Output Equivalent Circuit

    Vcc

    Vout

    Transistor acts like a switchOutput is a voltage divider

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    TTL Totem Pole Output Equivalent Circuit

    Vcc

    Vout

    Transistor acts like a switchOutput is a voltage divider

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    TTL Totem Pole Output Equivalent Circuit

    Vcc

    Vout

    Transistor acts like a switch

    Output is a voltage divider

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    TTL Totem Pole Output Equivalent Circuit

    Vcc

    Vout

    Transistor acts like a switchOutput is a voltage divider

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs; output low

    Vcc

    Vout

    Upper transistor OFF (open switch)Lower transistor ON (closed switch)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Totem pole outputs; output high

    Vcc

    Vout

    Upper transistor ON (closed switch)Lower transistor OFF (open switch)The voltage at the output will depend on the current drawnbecause of the resistor.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector outputs

    Vout

    Single transistor; ON or OFF

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector outputs

    Vout

    Single transistor; ON or OFF

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector outputs

    Vout

    Single transistor; ON or OFF

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector outputs

    Vout

    Single transistor; ON or OFF

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector output equivalent circuit

    Vout

    Output is either grounded or floatingAn external pull-up resistor is required to produce a highoutput

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector output equivalent circuit

    Vout

    Output is either grounded or floatingAn external pull-up resistor is required to produce a highoutput

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector output equivalent circuit

    Vout

    Output is either grounded or floating

    An external pull-up resistor is required to produce a highoutput

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector output equivalent circuit

    Vout

    Output is either grounded or floatingAn external pull-up resistor is required to produce a highoutput

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output Low)

    Vsupply

    Vout

    Inside chip

    Transistor ON (closed switch)Vout pulled to GROUNDCurrent into gate

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output Low)Vsupply

    Vout

    Inside chip

    Transistor ON (closed switch)Vout pulled to GROUNDCurrent into gate

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output Low)Vsupply

    Vout

    Inside chip

    Transistor ON (closed switch)

    Vout pulled to GROUNDCurrent into gate

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output Low)Vsupply

    Vout

    Inside chip

    Transistor ON (closed switch)Vout pulled to GROUND

    Current into gate

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output Low)Vsupply

    Vout

    Inside chip

    Transistor ON (closed switch)Vout pulled to GROUNDCurrent into gate

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    Output circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector Output Equivalent Circuit (Output High)Vsupply

    Vout

    Inside chip

    Transistor OFF (open switch)Vout pulled to VsupplyCurrent from supply

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Why use open collector gates?

    More currentMixing logic familiesWired ANDing of outputsBidirectional communication

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Why use open collector gates?

    More current

    Mixing logic familiesWired ANDing of outputsBidirectional communication

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Why use open collector gates?

    More currentMixing logic families

    Wired ANDing of outputsBidirectional communication

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Why use open collector gates?

    More currentMixing logic familiesWired ANDing of outputs

    Bidirectional communication

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Why use open collector gates?

    More currentMixing logic familiesWired ANDing of outputsBidirectional communication

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.

    A TTL gate can sink 16 mA.A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.

    A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.A TTL open collector gate can source ?

    A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?

    Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    More current

    A TTL gate can source 0.4 mA.A TTL gate can sink 16 mA.A TTL open collector gate can source ?A TTL open collector gate can sink 16 mA.

    Note: IOH for open-collector gate?Look at the sign given for IOH , and consider what that means.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Mixing logic families

    VOH for TTL is 2.4V.VIH for 4.5V HC(MOS) is 3.15V.VIH for 6V HC(CMOS) is 4.20V.

    ExamplesTTL open collector output can feed into 5V HC(CMOS) if theoutput is pulled up to 5V. (But Vcc is still 5V!)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Mixing logic families

    VOH for TTL is 2.4V.

    VIH for 4.5V HC(MOS) is 3.15V.VIH for 6V HC(CMOS) is 4.20V.

    ExamplesTTL open collector output can feed into 5V HC(CMOS) if theoutput is pulled up to 5V. (But Vcc is still 5V!)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Mixing logic families

    VOH for TTL is 2.4V.VIH for 4.5V HC(MOS) is 3.15V.

    VIH for 6V HC(CMOS) is 4.20V.

    ExamplesTTL open collector output can feed into 5V HC(CMOS) if theoutput is pulled up to 5V. (But Vcc is still 5V!)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Mixing logic families

    VOH for TTL is 2.4V.VIH for 4.5V HC(MOS) is 3.15V.VIH for 6V HC(CMOS) is 4.20V.

    ExamplesTTL open collector output can feed into 5V HC(CMOS) if theoutput is pulled up to 5V. (But Vcc is still 5V!)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Mixing logic families

    VOH for TTL is 2.4V.VIH for 4.5V HC(MOS) is 3.15V.VIH for 6V HC(CMOS) is 4.20V.

    ExamplesTTL open collector output can feed into 5V HC(CMOS) if theoutput is pulled up to 5V. (But Vcc is still 5V!)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Totem pole outputs tied together

    Which gate will win? (Think about current limits.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Totem pole outputs tied together

    Which gate will win? (Think about current limits.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Totem pole outputs tied together

    Which gate will win?

    (Think about current limits.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Totem pole outputs tied together

    Which gate will win? (Think about current limits.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Wire ANDing of outputs

    Vsupply

    Vout

    No gate is grounded, so output is pulled high.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Wire ANDing of outputs

    Vsupply

    Vout

    No gate is grounded, so output is pulled high.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Wire ANDing of outputs

    Vsupply

    Vout

    No gate is grounded, so output is pulled high.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Wire ANDing of outputs

    Vsupply

    Vout

    One gate is grounded, so output is low.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Wire ANDing of outputs

    Vsupply

    Vout

    One gate is grounded, so output is low.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Bidirectional communication

    If two (or more) devices are connected to the same open collectorsignal, then the signal can be an input or an output for both.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Bidirectional communication

    If two (or more) devices are connected to the same open collectorsignal, then the signal can be an input or an output for both.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor Calculations

    How do you calculate the pull-up resistor value?When the output is low, the gate must be able to sink thecurrent from the pull-up resistor and anything else connected.This will produce a minimum value for the resistor.When the output is high, the current through the pull-upresistor must be high enough for whatever is connected to it.This will produce a maximum value for the resistor.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor Calculations

    How do you calculate the pull-up resistor value?

    When the output is low, the gate must be able to sink thecurrent from the pull-up resistor and anything else connected.This will produce a minimum value for the resistor.When the output is high, the current through the pull-upresistor must be high enough for whatever is connected to it.This will produce a maximum value for the resistor.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor Calculations

    How do you calculate the pull-up resistor value?When the output is low, the gate must be able to sink thecurrent from the pull-up resistor and anything else connected.This will produce a minimum value for the resistor.

    When the output is high, the current through the pull-upresistor must be high enough for whatever is connected to it.This will produce a maximum value for the resistor.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor Calculations

    How do you calculate the pull-up resistor value?When the output is low, the gate must be able to sink thecurrent from the pull-up resistor and anything else connected.This will produce a minimum value for the resistor.When the output is high, the current through the pull-upresistor must be high enough for whatever is connected to it.This will produce a maximum value for the resistor.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    1 0X

    When the output is low, Rmin = (Vcc − VOL) / (IOL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    1 0X

    When the output is low, Rmin = (Vcc − VOL) / (IOL)(If R were smaller, the output couldn’t be kept low.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    1 1

    IILX

    If another gate follows, then the output has to sink from boththe resistor and the gate input, so the current through R mustbe REDUCED.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    1 1

    IILX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − IIL)(Current through R is reduced by IIL.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    2 1

    IILXX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − IIL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    2 1

    IILXX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − IIL)Another gate with a wired-OR output won’t change thecurrent through R, since its output is floating.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    2 1

    IILXX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − 2 × IIL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    3 2

    IILXXX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − 2 × IIL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    3 3

    IILXXX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − 3 × IIL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output lowCalculating Rmin

    M N

    IILX

    X

    XX

    When the output is low, Rmin = (Vcc − VOL) / (IOL − N × IIL)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    1 0

    IIHX

    When the output is high, Rmax = (Vcc − VOH) / (IOH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    1 0

    IIHX

    When the output is high, Rmax = (Vcc − VOH) / (IOH)(If R were bigger, VOH wouldn’t be guaranteed.)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    1 1

    IIHX

    If another gate follows, then the current has to pull both theresistor and the gate input HIGH, so the current through Rmust be INCREASED.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    1 1

    IIHX

    When the output is high, Rmax = (Vcc − VOH) / (IOH + IIH)(Current through R is increased by IIH .)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    2 1

    IIHXX

    Another gate with a wired-OR output will also need to bepulled HIGH, so the current must be INCREASED.

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    2 1

    IIHXX

    When the output is high,Rmax = (Vcc − VOH) / (2 × IOH + IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    2 2

    IIHXX

    When the output is high,Rmax = (Vcc − VOH) / (2 × IOH + 2 × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    3 2

    IIHXXX

    When the output is high,Rmax = (Vcc − VOH) / (3 × IOH + 2 × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    3 3

    IIHXXX

    When the output is high,Rmax = (Vcc − VOH) / (3 × IOH + 3 × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    Pull-up Resistor; output highCalculating Rmax

    M N

    IIHXXX

    X

    When the output is high,Rmax = (Vcc − VOH) / (M × IOH + N × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    So, to summarize:

    Rmin = (Vcc − VOL) / (IOL − N × IIL)Rmax = (Vcc − VOH) / (M × IOH + N × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    So, to summarize:Rmin = (Vcc − VOL) / (IOL − N × IIL)

    Rmax = (Vcc − VOH) / (M × IOH + N × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    More currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    So, to summarize:Rmin = (Vcc − VOL) / (IOL − N × IIL)Rmax = (Vcc − VOH) / (M × IOH + N × IIH)

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    CMOS Output circuit

    CMOS output

    VDD

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    CMOS Output circuit

    CMOS output

    VDD

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    CMOS Output circuit

    CMOS output

    VDD

    Vout

    Two transistors

    Only one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

  • Totem pole outputsOpen collector outputs

    Open Collector AdvantagesCMOS outputs

    CMOS Output circuit

    CMOS output

    VDD

    Vout

    Two transistorsOnly one on at one time

    Terry Sturtevant Electronics Logic Gates: Open Collector Output

    Totem pole outputsOutput circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open collector outputsOutput circuitOutput equivalent circuitEquivalent circuit;output lowEquivalent circuit;output high

    Open Collector AdvantagesMore currentMixing logic familiesWire ANDing of outputsBidirectional communicationPull-up Resistor Calculations

    CMOS outputsCMOS Output circuit