參數(shù)資料
型號: 74ABT5074PW
廠商: NXP SEMICONDUCTORS
元件分類: 通用總線功能
英文描述: Synchronizing dual D-type flip-flop with metastable immune characteristics
中文描述: ABT SERIES, DUAL POSITIVE EDGE TRIGGERED D FLIP-FLOP, COMPLEMENTARY OUTPUT, PDSO14
封裝: 4.40 MM, PLASTIC, MO-153, SOT-402-1, TSSOP1-14
文件頁數(shù): 3/7頁
文件大小: 100K
代理商: 74ABT5074PW
Philips Semiconductors Advanced BiCMOS Products
Product specification
74ABT5074
Synchronizing dual D-type flip-flop
with metastable immune characteristics
December 15, 1994
3
METASTABLE IMMUNE CHARACTERISTICS
Philips Semiconductors uses the term ‘metastable immune’ to
describe characteristics of some of the products in its family. By
running two independent signal generators (see Figure 1) at nearly
the same frequency (in this case 10MHz clock and 10.02MHz data)
the device-under-test can often be driven into a metastable state. If
the Q output is then used to trigger a digital scope set to infinite
persistence the Q output will build a waveform. An experiment was
run by continuously operating the devices in the region where
metastability will occur.
D
Q
Q
CP
TRIGGER
DIGITAL
SCOPE
INPUT
SIGNAL
GENERATOR
SA00004
SIGNAL
GENERATOR
Figure 1.
Test Setup
After determining the T
0
and
τ
of the flop, calculating the mean time
between failures (MTBF) is simple. Suppose a designer wants to
use the 74ABT5074 for synchronizing asynchronous data that is
arriving at 10MHz (as measured by a frequency counter), has a
clock frequency of 50MHz, and has decided that he would like to
sample the output of the 74ABT5074 7 nanoseconds after the clock
edge. He simply plugs his number into the following equation:
MTBF = e
(t’/
τ
)
/ T
O
*f
C
*f
I
In this formula, f
C
is the frequency of the clock, f
I
is the average
input event frequency, and t’ is the time after the clock pulse that the
output is sampled (t’ > h, h being the normal propagation delay). In
this situation the f
I
will be twice the data frequency of 20 MHz
because input events consist of both of low and high transitions.
Multiplying f
I
by f
C
gives an answer of 10
15
Hz
2
. From Figure 2 it is
clear that the MTBF is greater than 10
10
seconds. Using the above
formula the actual MTBF is 1.69
×
10
10
seconds or about 535 years.
E6
E8
E10
E12
E14
E15 = fc*fi
E13
E12
E11
E10
E9
E8
E7
E6
E5
10,000 YEARS
100 YEARS
ONE YEAR
ONE WEEK
MTBF
(SECONDS)
t’ (NANOSECONDS)
4
5
6
7
8
MTBF = e
(t’/
τ
)
/T
O
*f
C
*f
I
SA00005
V
CC
= 5V, T
amb
= 25
°
C,
τ
=94ps, To = 1.3x10
7
sec
Figure 2.
Mean Time Between Failures (MTBF) versus t’
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PDF描述
74ABT5074DB Synchronizing dual D-type flip-flop with metastable immune characteristics
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74ABT534AD,112 功能描述:觸發(fā)器 OCTAL D F/F INV 3-S RoHS:否 制造商:Texas Instruments 電路數(shù)量:2 邏輯系列:SN74 邏輯類型:D-Type Flip-Flop 極性:Inverting, Non-Inverting 輸入類型:CMOS 輸出類型: 傳播延遲時間:4.4 ns 高電平輸出電流:- 16 mA 低電平輸出電流:16 mA 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:X2SON-8 封裝:Reel
74ABT534AD,118 功能描述:觸發(fā)器 OCTAL D F/F INV 3-S RoHS:否 制造商:Texas Instruments 電路數(shù)量:2 邏輯系列:SN74 邏輯類型:D-Type Flip-Flop 極性:Inverting, Non-Inverting 輸入類型:CMOS 輸出類型: 傳播延遲時間:4.4 ns 高電平輸出電流:- 16 mA 低電平輸出電流:16 mA 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:X2SON-8 封裝:Reel