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Interface Threshold Voltage Levels

Comparison of Input and Output [I/O] logic switching levels for the CMOS [5V], PECL [5V], RS422/485, RS232, LVDS, BTL, GTL logic families.
The graph above provides a comparison between the Input and Output [I/O] logic switching levels for a few different Interface bus types.
The output logic levels above are defined by the Terms section below. For a review of Noise Margin numbers and a short description of many
of the IC logic families , refer to the Logic Family Selection page. A graph for Low Voltage [LV] devices resides on the LV Logic Threshold page.
An additional chart of Standard Logic Voltage levels is provided on the Logic Threshold Voltage Levels page


Terms -
V_CC: The voltage applied to the power pin(s). In most cases the voltage the device needs to operate at.
V_IH: [Voltage Input High] The minimum positive voltage applied to the input which will be accepted by the device as a logic high.
V_IL: [Voltage Input Low] The maximum positive voltage applied to the input which will be accepted by the device as a logic low.
V_OL: [Voltage Output Low] The maximum positive voltage from an output which the device considers will be accepted as the maximum positive low level.
V_OH: [Voltage Output High] The maximum positive voltage from an output which the device considers will be accepted as the minimum positive high level.
V_T: [Threshold Voltage] The voltage applied to a device which is "transition-Operated", which cause the device to switch. May also be listed as a '+' or '-' value.

Description of TTL, ECL and CMOS Glue Logic Families

  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 Plus                          
   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*


Design Key words for this page: Glue Logic Families, CMOS, TTL, ECL, Speed, IC, Integrated Circuits, Propagation delay, Logic Types, logic switching levels, Output voltage, Low-Voltage, Threshold Voltage, 74xx, 74AC00, 74HC, 74AHC00, Description, Digital Logic, Definition for Logic family, Logic Terms, TTL: Transistor Transistor Logic, ECL: Emitter Coupled Logic, CMOS: Complementary Metal-Oxide Semiconductor, BICMOS: Bipolar Complementary Metal Oxide Semiconductor 答 1: 图中RS-422和RS-485的部分对吗？