The 74F5074 is a dual positive edge–triggered D–type featuring
individual data, clock, set and reset inputs; also true and
complementary outputs.
Set (S
Dn) and reset (RDn) are asynchronous active low inputs and
operate independently of the clock (CPn) input. Data must be stable
just one setup time prior to the low–to–high transition of the clock for
guaranteed propagation delays.
Clock triggering occurs at a voltage level and is not directly related
to the transition time of the positive–going pulse. Following the hold
time interval, data at the Dn input may be changed without affecting
the levels of the output.
The 74F5074 is designed so that the outputs can never display a
metastable state due to setup and hold time violations. If setup time
and hold time are violated the propagation delays may be extended
beyond the specifications but the outputs will not glitch or display a
metastable state. Typical metastability parameters for the 74F5074
are: τ ≅ 135ps and T
≅ 9.8 X 10
o
6
sec where τ represents a
function of the rate at which a latch in a metastable state resolves
that condition and T
represents a function of the measurement of
0
the propensity of a latch to enter a metastable state.
Metastable Immune Characteristics
Philips Semiconductor uses the term ’metastable immune’ to
describe characteristics of some of the products in its family.
Specifically the 74F50XXX family presently consist of 4 products
which will not glitch or display an output anomaly under any
circumstances including setup and hold time violations. This claim is
easily verified on the 74F5074. By running two independent signal
generators (see Fig. 1) at nearly the same frequency (in this case
10MHz clock and 10.02 MHz data) the device–under–test can be
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
build a waveform. An experiment was run by continuously operating
the devices in the region where metastability will occur.
output will
When the device–under–test is a 74F74 (which was not designed
with metastable immune characteristics) the waveform will appear
as in Fig. 2.
Figure 2 shows clearly that the Q
output can vary in time with
respect to the Q trigger point. This also implies that the Q or Q
output waveshapes may be distorted. This can be verified on an
analog scope with a charge plate CRT. Perhaps of even greater
interest are the dots running along the 3.5V volt line in the upper
right hand quadrant. These show that the Q
output did not change
state even though the Q output glitched to at least 1.5 volts, the
trigger point of the scope.
When the device–under–test is a metastable immune part, such as
the 74F5074, the waveform will appear as in Fig. 3. The 74F5074 Q
output will appear as in Fig. 3. The 74F5074 Q output will not vary
with respect to the Q trigger point even when the a part is driven into
a metastable state. Any tendency towards internal metastability is
resolved by Philips Semiconductor patented circuitry. If a metastable
event occurs within the flop the only outward manifestation of the
event will be an increased clock–to–Q/Q
propagation delay. This
propagation delay is, of course, a function of the metastability
characteristics of the part defined by τ and T
0.
The metastability characteristics of the 74F5074 and related part
types represent state–of–the–art TTL technology.
After determining the T
and t of the flop, calculating the mean time
0
between failures (MTBF) is simple. Suppose a designer wants to
use the 74F5074 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 74F5074 10 nanoseconds after the clock
edge. He simply plugs his number into the equation below:
MTBF = e
(t’/t)
/ TofCf
I
In this formula, fC is the frequency of the clock, fI 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
because input events consist of both of low and high transitions.
Multiplying f
clear that the MTBF is greater than 10
formula the actual MTBF is 1.51 X 10
H =High voltage level
h =High voltage level one setup time prior to low–to–high clock transition
L =Low voltage level
l=Low voltage level one setup time prior to low–to–high clock transition
NC=No change from the previous setup
X =Don’t care
↑ =Low–to–high clock transition
=Not low–to–high clock transition
↑
* =This setup is unstable and will change when either set or reset return to the high level
(Operation beyond the limit set forth in this table may impair the useful life of the device. Unless otherwise noted these limits are over the
operating free air temperature range.)
SYMBOL
V
V
I
IN
V
I
OUT
T
T
CC
IN
OUT
amb
stg
Supply voltage–0.5 to +7.0V
Input voltage –0.5 to +7.0V
Input current–30 to +5mA
Voltage applied to output in high output state–0.5 to V
Current applied to output in low output state40mA
Operating free air temperature range0 to +70
Low–level output current20mA
Operating free air temperature range0 +70
PARAMETERRATINGUNIT
CC
V
°C
°C
T
= –40 to +85°C
A
MINNOMMAXUNIT
VCC ± 10%
VCC ± 5%
–12mA
–15mA
°C
DC ELECTRICAL CHARACTERISTICS
(Over recommended operating free-air temperature range unless otherwise noted.)
SYMBOL
V
OH
V
OL
V
IK
I
I
I
IH
I
IL
I
OS
I
CC
High–level output voltageVCC = MIN, VIL =
Low–level output voltage
Input clamp voltageVCC = MIN, II = I
Input current at maximum input voltageVCC = MAX, VI = 7.0V100µA
High–level input currentVCC = MAX, VI = 2.7V20µA
Low–level input currentDnVCC = MAX, VI = 0.5V-250µA
Short circuit output current
Supply current4 (total)VCC = MAX2030mA
NOTES:
1. For conditions shown as MIN or MAX, use the appropriate value specified under recommended operating conditions for the applicable type.
2. All typical values are at V
3. Not more than one output should be shorted at a time. For testing IOS, the use of high-speed test apparatus and/or sample-and-hold
techniques are preferable in order to minimize internal heating and more accurately reflect operational values. Otherwise, prolonged shorting
of a high output may raise the chip temperature well above normal and thereby cause invalid readings in other parameter tests. In any
sequence of parameter tests, I
4. Measure I
with the clock input grounded and all outputs open, then with Q and Q outputs high in turn.
This data sheet contains the design target or goal specifications for product development.
Specification may change in any manner without notice.
This data sheet contains preliminary data, and supplementary data will be published at a later date.
Philips Semiconductors reserves the right to make chages at any time without notice in order to
improve design and supply the best possible product.
This data sheet contains final specifications. Philips Semiconductors reserves the right to make
changes at any time without notice in order to improve design and supply the best possible product.
[1]
[1] Please consult the most recently issued datasheet before initiating or completing a design.
Definitions
Short-form specification — The data in a short-form specification is extracted from a full data sheet with the same type number and title. For
detailed information see the relevant data sheet or data handbook.
Limiting values definition — Limiting values given are in accordance with the Absolute Maximum Rating System (IEC 134). Stress above one
or more of the limiting values may cause permanent damage to the device. These are stress ratings only and operation of the device at these or
at any other conditions above those given in the Characteristics sections of the specification is not implied. Exposure to limiting values for extended
periods may affect device reliability.
Application information — Applications that are described herein for any of these products are for illustrative purposes only. Philips
Semiconductors make no representation or warranty that such applications will be suitable for the specified use without further testing or
modification.
Disclaimers
Life support — These products are not designed for use in life support appliances, devices or systems where malfunction of these products can
reasonably be expected to result in personal injury . Philips Semiconductors customers using or selling these products for use in such applications
do so at their own risk and agree to fully indemnify Philips Semiconductors for any damages resulting from such application.
Right to make changes — Philips Semiconductors reserves the right to make changes, without notice, in the products, including circuits, standard
cells, and/or software, described or contained herein in order to improve design and/or performance. Philips Semiconductors assumes no
responsibility or liability for the use of any of these products, conveys no license or title under any patent, copyright, or mask work right to these
products, and makes no representations or warranties that these products are free from patent, copyright, or mask work right infringement, unless
otherwise specified.
Philips Semiconductors
811 East Arques Avenue
P.O. Box 3409
Sunnyvale, California 94088–3409
Telephone 800-234-7381
Copyright Philips Electronics North America Corporation 1998
All rights reserved. Printed in U.S.A.
print codeDate of release: 10-98
Document order number:9397-750-05207
yyyy mmm dd
12
Loading...
+ hidden pages
You need points to download manuals.
1 point = 1 manual.
You can buy points or you can get point for every manual you upload.