Logic Family Variations
Paul Baker
Posts: 6,351
This has been provided by request (from the SX forum) migrated over here because it is off-topic for that forum.
All 74XX families should have pin mappings which are the same for a given part. As per your specific question regarding HC vs HCT: TI's description for the 74HC(T)00 is: The CD54HC00, CD74HC00, CD54HCT00, and CD74HCT00 logic gates utilize silicon gate CMOS technology to achieve operating speeds similar to LSTTL gates with the low power consumption of standard CMOS integrated circuits. All devices have the ability to drive 10 LSTTL loads. The 74HCT logic family is functionally pin compatible with the standard 74LS logic family. (this was obtained from here: http://rocky.digikey.com/WebLib/Texas%20Instruments/Web%20data/CD74HC(T)00.pdf)
Both families apear to be able·of taking input from and driving both CMOS and TTL. (If your operating the HC at 5V). The main difference between the families is that HC can be operated at a range of voltages, HCT requires 5V.
This page may help you comparing various levels: http://www.interfacebus.com/voltage_threshold.html
(the following reprinted from http://www.interfacebus.com/IC_Output_Propagation_Rate.html)
· Device Families:
TTL (74xx)······················· True TTL
74L································· Low power
74S································· Schottky
74H································ High speed
74LS······························· Low power - Schottky···············
74AS······························ Advanced - Schottky········
74ALS······························Advanced - Low power - Schottky···············
74F(AST)························ Fast - (Advanced - Schottky)·······
74C································ CMOS...................check Vcc levels
74HC (U)························ High speed - CMOS (Unbuffered output)·······
74HCT··························· ·High speed - CMOS - TTL inputs·······
74AHC···························· Advanced - High speed - CMOS·········
74AHCT·························· Advanced - High speed - CMOS - TTL inputs
74FCT (-A)······················ Fast - CMOS - TTL inputs (speed variations)
74FCT (-T, -AT)················Fast - CMOS - TTL inputs (speed variations)
74AC······························ Advanced - CMOS·························
74ACT·····························Advanced - CMOS - TTL inputs········
74FACT···························AC, ACT (Q) series·················
74ACQ····························Advanced - CMOS - Quiet outputs················
74ACTQ·························· Advanced - CMOS - TTL inputs - Quiet outputs
·· Bus Driver Families
74ABT···························· Advanced - BiCMOS - Technology···············
74ABTE·························· ABT - Enhanced Transceiver Logic···············
74ABTH·························· Advanced - BiCMOS - Technology - bus Hold
74BCT···························· BiCMOS - TTL inputs ················
74BTL····························· Backplane - Transceiver - Logic·········
74GTL·····························Gunning - Transceiver - Logic·········
74GTLP··························· GTL (Motorola)·························
·· Low Voltage Families
74ALB···························· Advanced - Low Voltage - BiCMOS················
74LV (U)························ Low - Voltage (Unbuffered output)········
74LVC (R) (U)················· LV - CMOS (damping Resistor)(Unbuffered output)
74LVCH·························· Low - Voltage - CMOS - bus Hold················
74ALVC·························· Advanced - Low - Voltage - CMOS················
74LVT (R) (U)················· LV - TTL· (damping Resistor(Unbuffered output)
74LVTZ···························Low - Voltage - TTL - High Impedance power-up
74ALVC (R)···················· ALV - CMOS (bus Hold) (damping Resistor)
74ALVCH························Advanced - Low - Voltage - CMOS - bus Hold
74LCX···························· LV - CMOS (operates with 3v & 5v supplies)
74VCX··························· LV - CMOS (operates with 1.8v & 3.6v supplies
4000 ···························· True CMOS (non-TTL levels)·········
· ECL Device Families:
MEC I···························· 8nS*···············
MEC II·························· 2nS*················
MEC III························· (16XX)·1nS*· .......* = Rise & Fall Times
101xx··························· 100 series 10K ECL, 3.5nS*·········
102xx··························· 200 series 10K ECL, 2.5nS*·········
108xx··························· 800 series 10K ECL, voltage compensated, 3.5nS*
10Hxxx························· 10K - High speed, voltage compensated, 1.8nS*
10Exxx························· 10K - ECLinPS, voltage compensated, 800pS*
100xxx························· 100K, temperature compensated················
100Hxxx······················· 100K - High speed, temperature compensated
100Exxx······················· 100K - ECLinPS, temp, voltage comp., 800pS*
Post Edited (Paul Baker) : 1/18/2005 8:57:17 PM GMT
All 74XX families should have pin mappings which are the same for a given part. As per your specific question regarding HC vs HCT: TI's description for the 74HC(T)00 is: The CD54HC00, CD74HC00, CD54HCT00, and CD74HCT00 logic gates utilize silicon gate CMOS technology to achieve operating speeds similar to LSTTL gates with the low power consumption of standard CMOS integrated circuits. All devices have the ability to drive 10 LSTTL loads. The 74HCT logic family is functionally pin compatible with the standard 74LS logic family. (this was obtained from here: http://rocky.digikey.com/WebLib/Texas%20Instruments/Web%20data/CD74HC(T)00.pdf)
Both families apear to be able·of taking input from and driving both CMOS and TTL. (If your operating the HC at 5V). The main difference between the families is that HC can be operated at a range of voltages, HCT requires 5V.
This page may help you comparing various levels: http://www.interfacebus.com/voltage_threshold.html
(the following reprinted from http://www.interfacebus.com/IC_Output_Propagation_Rate.html)
· Device Families:
TTL (74xx)······················· True TTL
74L································· Low power
74S································· Schottky
74H································ High speed
74LS······························· Low power - Schottky···············
74AS······························ Advanced - Schottky········
74ALS······························Advanced - Low power - Schottky···············
74F(AST)························ Fast - (Advanced - Schottky)·······
74C································ CMOS...................check Vcc levels
74HC (U)························ High speed - CMOS (Unbuffered output)·······
74HCT··························· ·High speed - CMOS - TTL inputs·······
74AHC···························· Advanced - High speed - CMOS·········
74AHCT·························· Advanced - High speed - CMOS - TTL inputs
74FCT (-A)······················ Fast - CMOS - TTL inputs (speed variations)
74FCT (-T, -AT)················Fast - CMOS - TTL inputs (speed variations)
74AC······························ Advanced - CMOS·························
74ACT·····························Advanced - CMOS - TTL inputs········
74FACT···························AC, ACT (Q) series·················
74ACQ····························Advanced - CMOS - Quiet outputs················
74ACTQ·························· Advanced - CMOS - TTL inputs - Quiet outputs
·· Bus Driver Families
74ABT···························· Advanced - BiCMOS - Technology···············
74ABTE·························· ABT - Enhanced Transceiver Logic···············
74ABTH·························· Advanced - BiCMOS - Technology - bus Hold
74BCT···························· BiCMOS - TTL inputs ················
74BTL····························· Backplane - Transceiver - Logic·········
74GTL·····························Gunning - Transceiver - Logic·········
74GTLP··························· GTL (Motorola)·························
·· Low Voltage Families
74ALB···························· Advanced - Low Voltage - BiCMOS················
74LV (U)························ Low - Voltage (Unbuffered output)········
74LVC (R) (U)················· LV - CMOS (damping Resistor)(Unbuffered output)
74LVCH·························· Low - Voltage - CMOS - bus Hold················
74ALVC·························· Advanced - Low - Voltage - CMOS················
74LVT (R) (U)················· LV - TTL· (damping Resistor(Unbuffered output)
74LVTZ···························Low - Voltage - TTL - High Impedance power-up
74ALVC (R)···················· ALV - CMOS (bus Hold) (damping Resistor)
74ALVCH························Advanced - Low - Voltage - CMOS - bus Hold
74LCX···························· LV - CMOS (operates with 3v & 5v supplies)
74VCX··························· LV - CMOS (operates with 1.8v & 3.6v supplies
4000 ···························· True CMOS (non-TTL levels)·········
· ECL Device Families:
MEC I···························· 8nS*···············
MEC II·························· 2nS*················
MEC III························· (16XX)·1nS*· .......* = Rise & Fall Times
101xx··························· 100 series 10K ECL, 3.5nS*·········
102xx··························· 200 series 10K ECL, 2.5nS*·········
108xx··························· 800 series 10K ECL, voltage compensated, 3.5nS*
10Hxxx························· 10K - High speed, voltage compensated, 1.8nS*
10Exxx························· 10K - ECLinPS, voltage compensated, 800pS*
100xxx························· 100K, temperature compensated················
100Hxxx······················· 100K - High speed, temperature compensated
100Exxx······················· 100K - ECLinPS, temp, voltage comp., 800pS*
Post Edited (Paul Baker) : 1/18/2005 8:57:17 PM GMT
Comments
Man I love this site. It covers so much useful information, I've spent all evening reading through the pages and I still have only seen the tip of the iceberg. I've seen the answers to many questions posed in these forums such as EMI reduction etc. It will take me quite a while to peruse it's wealth of material.
Paul
Oh and TI has a Logic Family selection guide: http://focus.ti.com/lit/ml/sdyu001v/sdyu001v.pdf
Post Edited (Paul Baker) : 1/19/2005 5:14:11 AM GMT