參數(shù)資料
型號(hào)： HD74AC
廠商： Hitachi,Ltd.
英文描述： HD74AC Series Common Information
中文描述： HD74AC系列通用信息
文件頁(yè)數(shù)： 47/52頁(yè)
文件大?。?/td> 220K
代理商： HD74AC
Design Considerations
46
It is good practice to distribute decoupling capacitors evenly through the logic, placing one capacitor for
every package.
5.2 Capacitor Types
Decoupling capacitors need to be of the high K ceramic type with low equivalent series resistance (ESR),
consisting primarily of series inductance and series resistance. Capacitors using 5ZU dielectric have
suitable properties and make a good choice for decoupling capacitors; they offer minimum cost and
effective performance.
6. TTL-Compatible CMOS Designs Require Delta I
CC
Consideration
The FACT product line is composed of two types of advanced CMOS circuits: HD74AC and HD74ACT
devices. HD74ACT indicates an advanced CMOS device with TTL-type input thresholds for direct
replacement of LS and ALS circuits. As this HD74ACT series is used to replace TTL, the Delta I
CCT
specification must be considered; this spec may be confusing and misleading to the engineer unfamiliar
with CMOS.
It is important to understand the concept of Delta I
CCT
and how to use it within a design. First, consider
where Delta I
CCT
initiates. Most CMOS input structures are of the totem pole type with an n-channel
transistor in a series with a p-channel transistor as illustrated in figure 20.
P Channel
N Channel
V
CC
To
Internal
Logic
Input Pad
Figure 20 CMOS Input Structure
These two transistors can be modeled as variable resistors with resistances varying according to the input
voltage. The resistance of an on transistor is approximately 50
while the resistance of an off transistor is
generally greater than 5 M
. When the input to this structure is at either ground or V
CC
, one transistor will
be on and one will be off. The total series resistance of this pair will be the combination of the two
individual resistances, greater than 5 M
. The leakage current will then be less than 1
μ
A. When the input
is between ground and V
CC
, the resistance of the on transistor will increase while the resistance of the off
transistor will decrease. The net resistance will drop due to the much larger value of the off resistance.
The total series resistance can be as low as 600
. This reduction in series resistance of the input structure
will cause a corresponding increase in I
CC
as current flows through the input structure. Figure 21 depicts
typical I
CC
variance with input voltage for an HD74ACT device.
相關(guān)PDF資料
PDF描述
HD74ALVC162244 16-bit Buffer / Driver with 3-state Outputs(帶三態(tài)輸出的16位緩沖器/驅(qū)動(dòng)器)
HD74ALVC162334 16-bit Universal Bus Driver with 3-state Outputs(帶三態(tài)輸出的16位通用總線(xiàn)驅(qū)動(dòng)器)
HD74ALVC16244 16-bit Buffer / Driver with 3-state Outputs(帶三態(tài)輸出的16位緩沖器/驅(qū)動(dòng)器)
HD74ALVC162831 1-bit to 4-bit Address Register / Driver with 3-state Outputs(三態(tài)輸出的1位-4位地址寄存器/驅(qū)動(dòng)器)
HD74ALVC162834A 1-Of-8 Data Selectors/Multiplexers 16-CDIP -55 to 125
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
HD74AC00 制造商:HITACHI 制造商全稱(chēng):Hitachi Semiconductor 功能描述:Quad 2-Input NAND Gate
HD74AC00FP 制造商:未知廠家 制造商全稱(chēng):未知廠家 功能描述:Quad 2-input NAND Gate
HD74AC00FPEL 制造商:RENESAS 制造商全稱(chēng):Renesas Technology Corp 功能描述:Quad 2-Input NAND Gate
HD74AC00P 制造商:RENESAS 制造商全稱(chēng):Renesas Technology Corp 功能描述:Quad 2-Input NAND Gate
HD74AC00RPEL 制造商:RENESAS 制造商全稱(chēng):Renesas Technology Corp 功能描述:Quad 2-Input NAND Gate
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