參數(shù)資料
型號(hào)： MC74AC00M
廠商： ON SEMICONDUCTOR
元件分類： 門電路
英文描述： AC SERIES, QUAD 2-INPUT NAND GATE, PDSO14
封裝： EIAJ, PLASTIC, 14 PIN
文件頁(yè)數(shù)： 22/45頁(yè)
文件大?。?/td> 434K
代理商： MC74AC00M
http://onsemi.com
33
Well-designed circuit
boards
also
help
eliminate
manufacturing and testing problems.
Another recommended practice is to segment the board
into a high-speed area, a medium-speed area and a low-
speed area. The circuit areas with high current requirements
(i.e., buffer circuits and high-speed logic) should be as close
to the power supplies as possible; low-speed circuit areas
can be furthest away.
Decoupling capacitors should be adjacent to all buffer
chips; they should be distributed throughout the logic: one
capacitor per chip. Transmission lines need to be terminated
to keep reflections minimal. To minimize crosstalk, long
signal lines should not be close together.
Crosstalk
The problem of crosstalk and how to deal with it is
becoming more important as system performance and board
densities increase. Crosstalk is the capacitive coupling of
signals from one line to another. The amplitude of the noise
generated on the inactive line is directly related to the edge
rates of the signal on the active line, the proximity of the two
lines and the distance that the two lines are adjacent.
Crosstalk has two basic causes. Forward crosstalk,
Figure 1–41a, is caused by the wavefront propagating down
the printed circuit trace at two different velocities. This
difference in velocities is due to the difference in the
dielectric constants of air (
∈r = 1) and epoxy glass (∈r = 4.7).
As the wave propagates down the trace, this difference in
velocities will cause one edge to reach the end before the
other. This delay is the cause of forward crosstalk; it
increases with longer trace length, so consequently the
magnitude of forward crosstalk will increase with distance.
Reverse crosstalk, Figure 1–41b, is caused by the mutual
inductance and capacitance between the lines which is a
transformer action. Reverse crosstalk increases linearly with
distance up to a critical length. This critical length is the
distance that the signal can travel during its rise or fall time.
Although crosstalk cannot be totally eliminated, there are
some design techniques that can reduce system problems
resulting from crosstalk. FACT’s industry-leading noise
margins make systems immune to crosstalk-related
problems easier to design. FACT’s AC noise margins,
shown in Figure 1–42a and 1–42b, exemplify the
outstanding immunity to everyday noise which can affect
system reliability.
TIME (ns) (5.0 ns/DIV)
Figure 1–41a. Forward Crosstalk on PCB Traces
0.0 V
VOL
T
AGE
(V)
Key
Vertical Scale
Horizontal Scale
Active Driver
1.0 V/Div
50 ns/Div
Fwd Crosstalk
0.2 V/Div
5.0 ns/Div
Active Receiver
1.0 V/Div
5.0 ns/Div
This figure shows traces taken on a test fixture designed to exaggerate
the amplitude of crosstalk pulses.
VOL
T
AGE
(V)
TIME (ns) (5.0 ns/DIV)
Figure 1-41b. Reverse Crosstalk on PCB Traces
0.0 V
Key
Vertical Scale
Horizontal Scale
Active Driver
1.0 V/Div
50 ns/Div
Fwd Crosstalk
0.2 V/Div
5.0 ns/Div
Active Receiver
1.0 V/Div
5.0 ns/Div
This figure shows traces taken on a test fixture designed to exaggerate
the amplitude of crosstalk pulses.
相關(guān)PDF資料
PDF描述
MC74AC04MR1 AC SERIES, HEX 1-INPUT INVERT GATE, PDSO14
MC74AC05MR2 AC SERIES, HEX 1-INPUT INVERT GATE, PDSO14
MC74ACT05DT ACT SERIES, HEX 1-INPUT INVERT GATE, PDSO14
MC74AC109N AC SERIES, DUAL POSITIVE EDGE TRIGGERED J-KBAR FLIP-FLOP, COMPLEMENTARY OUTPUT, PDIP16
MC74AC109D AC SERIES, DUAL POSITIVE EDGE TRIGGERED J-KBAR FLIP-FLOP, COMPLEMENTARY OUTPUT, PDSO16
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MC74AC00MEL 功能描述:邏輯門 2-6V Quad 2-Input RoHS:否 制造商:Texas Instruments 產(chǎn)品:OR 邏輯系列:LVC 柵極數(shù)量:2 線路數(shù)量（輸入/輸出）:2 / 1 高電平輸出電流:- 16 mA 低電平輸出電流:16 mA 傳播延遲時(shí)間:3.8 ns 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DCU-8 封裝:Reel
MC74AC00MELG 功能描述:邏輯門 2-6V Quad 2-Input NAND RoHS:否 制造商:Texas Instruments 產(chǎn)品:OR 邏輯系列:LVC 柵極數(shù)量:2 線路數(shù)量（輸入/輸出）:2 / 1 高電平輸出電流:- 16 mA 低電平輸出電流:16 mA 傳播延遲時(shí)間:3.8 ns 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DCU-8 封裝:Reel
MC74AC00ML1 制造商:Rochester Electronics LLC 功能描述:- Bulk
MC74AC00MR1 制造商:Rochester Electronics LLC 功能描述:- Bulk
MC74AC00N 功能描述:邏輯門 2-6V Quad 2-Input RoHS:否 制造商:Texas Instruments 產(chǎn)品:OR 邏輯系列:LVC 柵極數(shù)量:2 線路數(shù)量（輸入/輸出）:2 / 1 高電平輸出電流:- 16 mA 低電平輸出電流:16 mA 傳播延遲時(shí)間:3.8 ns 電源電壓-最大:5.5 V 電源電壓-最小:1.65 V 最大工作溫度:+ 125 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:DCU-8 封裝:Reel
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