Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
ElectronicsLogic Gates: Open Collector Output
Terry Sturtevant
Wilfrid Laurier University
November 13, 2012
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 Vsupply
Current 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 outputsPull-up Resistor Calculations
Why use open collector gates?
More currentMixing logic familiesWired ANDing of outputs
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-up Resistor Calculations
Why use open collector gates?
More current
Mixing logic familiesWired ANDing of outputs
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-up Resistor Calculations
Why use open collector gates?
More currentMixing logic families
Wired ANDing of outputs
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-up Resistor Calculations
Why use open collector gates?
More currentMixing logic familiesWired ANDing of outputs
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-up Resistor Calculations
Mixing logic families
VOH for TTL is 2.4V.VIH for 5V CMOS is 3.5V.VIH for 10V CMOS is 7V.
ExamplesTTL open collector output can feed into 10V CMOS if the outputis pulled up to 10V. (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 outputsPull-up Resistor Calculations
Mixing logic families
VOH for TTL is 2.4V.
VIH for 5V CMOS is 3.5V.VIH for 10V CMOS is 7V.
ExamplesTTL open collector output can feed into 10V CMOS if the outputis pulled up to 10V. (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 outputsPull-up Resistor Calculations
Mixing logic families
VOH for TTL is 2.4V.VIH for 5V CMOS is 3.5V.
VIH for 10V CMOS is 7V.
ExamplesTTL open collector output can feed into 10V CMOS if the outputis pulled up to 10V. (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 outputsPull-up Resistor Calculations
Mixing logic families
VOH for TTL is 2.4V.VIH for 5V CMOS is 3.5V.VIH for 10V CMOS is 7V.
ExamplesTTL open collector output can feed into 10V CMOS if the outputis pulled up to 10V. (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 outputsPull-up Resistor Calculations
Mixing logic families
VOH for TTL is 2.4V.VIH for 5V CMOS is 3.5V.VIH for 10V CMOS is 7V.
ExamplesTTL open collector output can feed into 10V CMOS if the outputis pulled up to 10V. (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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating Rmin
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating Rmin
2 2
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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output low
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating Rmax
Terry Sturtevant Electronics Logic Gates: Open Collector Output
Totem pole outputsOpen collector outputs
Open Collector AdvantagesCMOS outputs
More currentMixing logic familiesWire ANDing of outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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 outputsPull-up Resistor Calculations
Pull-up Resistor; output high
Calculating 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
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
