Technical Seminar H412
Project
Background
Discontinuity
Discovery
Physical
Testing
Nanosecond Discontinuity
Impact on Hot-Swap
Simulation
Testing
Solution
Material
Qualification
Conclusion
Hank Herrmann - AMP
Jack Kelly - Motorola
Timothy R. Minnick - AMP
1
Nanosecond Discontinuities...
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
...are NOT
pin bounce!!!
Solution
Material
Qualification
Conclusion
2
Session Outline
Project
Background
• Project Background
Discontinuity
Discovery
• Discovery of the Phenomenon
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
– Physical Testing
– Simulation Testing
• Solution
• Material Qualification
• Conclusion
3
The Basic System
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
Slot 1
•
•
•
•
Slot 2
Slot X
Intense Error-Free Data Rates(telecom)
Bus Architectures
Conductive Interfaces (i.e. connectors)
Hot-Swap Capability
4
The Hot-Swap System
Project
Background
Hot-Swap Card
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
Slot 1
Slot 2
Slot X
• Additional Energy Transfer
• Additional Signal Integrity Requirements
5
Motorola CPX8000 System
Project
Background
• Telecom Infrastructure Applications
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
• CompactPCI Architecture
• High Availability
• Data Intensive
Material
Qualification
Conclusion
• Device Redundant
6
Detection of a Discontinuity
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
7
Mechanical Connector Bounce
Project
Background
• Analyzed at birth of CPCI specification
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
• Typical speeds in microsecond range
• Pre-charge resistors
Solution
Material
Qualification
Conclusion
Present signal integrity design can not
respond to nanosecond discontinuities!!
8
Magnified 2mm HM Contact
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
9
Initial Discontinuity Test Set-Up
Hot-Swap Card
Project
Background
Discontinuity
Discovery
Backplane
5.0 V
Scope Probe
(2nd Channel)
4.7k-Ohm
4.7k-Ohm
Physical
Testing
Scope Probe
(1st Channel)
GND
Simulation
Testing
Solution
Engagement
Material
Qualification
Conclusion
Zoomed-inView
(~40 usec)
10
Electrical Testing
Project
Background
+5v
1K
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Vmeas
Standard
Receptacle
Oscilloscope
Standard
Pin
Solution
Material
Qualification
Conclusion
• Simple voltage divider
• Constant velocity fixture
11
Equipment References
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
• Discontinuity Detection
– Tektronix TDS 784A Digitizing Oscilloscope
– Motorola VxWorks Operating System
– Motorola CPX8000 Series Chassis & Cards
Solution
Material
Qualification
Conclusion
• Pin Testing and Resistance Profiling
– Tektronix TDS 684A Digitizing Oscilloscope
– Mating Fixture with Pneumatic Drive
12
Test Set-Up Results
Project
Background
6.0
Discontinuity
Discovery
Zoom-in Region
6.0
5.0
5.0
Solution
4.0
Voltage (V)
Simulation
Testing
4.0
Voltage (V)
Physical
Testing
3.0
2.0
1.0
0.0
44ns
-1.0
108.200
-1.0
108.230
108.260
108.290
Time (usec)
0
Conclusion
2.0
1.0
0.0
Material
Qualification
3.0
30
60
90
120
Time (usec)
13
150
108.320
108.350
Simulation - CPCI Network
Project
Background
Hot-Swap Card
1.0 V
Discontinuity
Discovery
Driver
Receiver
Physical
Testing
1.0 V
1.0 V
10k-Ohm
Simulation
Testing
10-Ohm
10k-Ohm
Solution
1.5"
10k-Ohm
1.5"
10-Ohm
1.5"
10-Ohm
Material
Qualification
0.8"
Conclusion
Slot 1
0.8"
Slot 2
0.8"
Slot 8
14
Simulation of the Discontinuity
Project
Background
6.0
disengagement point
re-engagment point
5.0
Discontinuity
Discovery
Driver Card
Hot-Swap Card
Receiver Card
4.0
Physical
Testing
bus signal above
receiver threshold
Simulation
Testing
Voltage (V)
3.0
2.0
Solution
1.0
Material
Qualification
0.0
-1.0
Conclusion
-2.0
0
5
10
15
20
Time (ns)
15
25
30
35
40
Simulation Summary
Project
Background
A
B
C
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
Pin
Receptacle
• Initial point of contact - low normal force
• Highly conductive interface
• Microscopic irregularities
16
Simulation Conclusions
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
=> Nanosecond discontinuities
=> Energy transfer onto the bus
=> Signal Impact
Solution
Material
Qualification
Any conductive hot-swap interface!!
Conclusion
17
Solutions
Project
Background
• Software control during live insertion
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
• Decrease low normal force zone
• Limit rate of energy taken from the bus
– lower daughtercard capacitance
• physical restructuring
• impact on signal integrity and timing
– add resistance during engagement
18
Resistive Pin Development
Project
Background
Unmated Receptacle and Pin
A
E
Resistive Coating
Discontinuity
Discovery
Physical
Testing
B C D
Receptacle
Pin
Simulation
Testing
Solution
Sufficient Normal Force Engagement Position
A
B C D
E
Material
Qualification
Conclusion
Receptacle
19
Pin
Isolation-to-Resistive Transition
Project
Background
6.00
disengagement point
re-engagement point
5.00
Discontinuity
Discovery
Driver Card
Hot-Swap Card
Receiver Card
4.00
Physical
Testing
gradual release
onto backplane
Simulation
Testing
Solution
Material
Qualification
Conclusion
Voltage (V)
3.00
2.00
acceptable level
1.00
0.00
-1.00
-2.00
0.0
5.0
10.0
15.0
20.0
Time (ns)
20
25.0
30.0
35.0
40.0
Electrical Verification
Project
Background
+5v
R1
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
1K
VDC
Vmeas
Standard
Receptacle
Rtip
Oscilloscope
Resistive
Tip Pin
Solution
Material
Qualification
Vmeas ∗ R1
Rtip =
Vdc - Vmeas
Conclusion
21
Resistance Profile
6
Project
Background
5.5
Simulation
Testing
Solution
4.5
Resistance (kOhms)
Physical
Testing
Cycle #1
5
Discontinuity
Discovery
Cycle #100
4
3.5
3
2.5
2
1.5
500-Ohm max
Material
Qualification
1
0.5
0
Conclusion
200-Ohm min
-0.5
0
0.5
1
Time (msec)
22
1.5
2
Mechanical Testing
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
Different Lighting on Magnified Pin - 250 Engagement Cycles
•
•
•
High-cycle durability
Exceptional adhesion to gold
Absence of debris
23
Qualification Testing
Project
Background
Discontinuity
Discovery
Physical
Testing
• 2mm HM product spec (108-1622)
– 250 cycle durability
– pin staging
Simulation
Testing
Solution
• Bellcore GR-1217-CORE (Telcordia)
Material
Qualification
Conclusion
• Resistance requirements
24
Conclusion - The Problem
Project
Background
6.0
disengagement point
re-engagment point
5.0
Discontinuity
Discovery
Driver Card
Hot-Swap Card
Receiver Card
4.0
Physical
Testing
bus signal above
receiver threshold
Simulation
Testing
Voltage (V)
3.0
2.0
Solution
1.0
Material
Qualification
0.0
-1.0
Conclusion
-2.0
0
5
10
15
20
Time (ns)
25
25
30
35
40
Conclusion - The Solution
Project
Background
6.00
disengagement point
re-engagement point
5.00
Discontinuity
Discovery
Driver Card
Hot-Swap Card
Receiver Card
4.00
Physical
Testing
gradual release
onto backplane
Simulation
Testing
Solution
Material
Qualification
Conclusion
Voltage (V)
3.00
2.00
acceptable level
1.00
0.00
-1.00
-2.00
0.0
5.0
10.0
15.0
20.0
Time (ns)
26
25.0
30.0
35.0
40.0
Conclusion - The Connector
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
27
The Quiet MateTM Contact
Project
Background
Discontinuity
Discovery
Physical
Testing
Simulation
Testing
Solution
Material
Qualification
Conclusion
28
3.3V CPCI System Discontinuity
Project
Background
4.00
disengagement point
3.50
Discontinuity
Discovery
3.00
2.50
Physical
Testing
Solution
bus signal above
receiver threshold
2.00
Voltage (V)
Simulation
Testing
Receiver Card
Hot-Swap Card
Driver Card
re-engagement
1.50
1.00
0.50
0.00
Material
Qualification
-0.50
-1.00
Conclusion
-1.50
0.0
5.0
10.0
15.0
20.0
25.0
Time (ns)
29
30.0
35.0
40.0
45.0
50.0
3.3V Quiet MateTM CPCI System
Project
Background
4.00
disengagement point
3.50
Discontinuity
Discovery
3.00
2.50
Physical
Testing
Solution
gradual release
onto backplane
2.00
Voltage (V)
Simulation
Testing
Driver Card
Receiver Card
Hot-Swap Card
re-engagement point
1.50
acceptable level
1.00
0.50
0.00
Material
Qualification
-0.50
-1.00
Conclusion
-1.50
0.0
5.0
10.0
15.0
20.0
25.0
Time (ns)
30
30.0
35.0
40.0
45.0
50.0
Nanosecond Discontinuities & Quiet MateTM Contacts
irregularities and the relative motion of the
structures at the near-zero normal force area
of engagement.
Nanosecond discontinuities are different
from “pin bounce”, in that they are not a
mechanical deflection and return of the
contact beam, but rather a result of the
relative motion and initial contact of the
conductive interface.
The Quiet MateTM Contact
February 10, 2000
1
Measured Discontinuity
6.0
Zoom-in Region
6.0
5.0
Nanosecond Discontinuties??
5.0
• Initial Contact Point - Low Normal Force
4.0
Voltage (V)
Voltage (V)
4.0
3.0
2.0
3.0
2.0
1.0
1.0
0.0
• Microscopic Irregularities
0.0
-1.0
108.200
-1.0
A
B
30
60
90
120
108.290
108.320
108.350
150
Time (usec)
C
3
Receptacle
108.260
Time (usec)
0
• Highly-Conductive Interface
44ns
108.230
February 10, 2000
Pin
• Different From Pin “Bounce”
2
Nanosecond discontinuities are extremely
difficult to capture with consistency. An
extensive understanding of the system and
how it responds to a live insertion event is
critical in detecting the phenomenon.
Advanced (and expensive) test probes,
measurement scopes, and specialized test
fixtures aid in the identification of the
intermittencies.
Data samples from one such test set-up are
clear enough to discern the faster
disruptions, due to the optimally reduced
time constant of the test-bed. The measured
waveforms were plotted on a voltage scale
to 5V against a physical engagement timescale. The recorded data is then focused on
the specific areas around the transition edges
of engagement and disengagement.
The measured waveform displays
intermittencies detected during a card
engagement event. When the irregularities
are magnified [seen as the waveform on the
right], a discontinuity of approximately 44
nanoseconds is measured.
The intermittencies are extremely erratic and
vary anywhere from 100’s of microseconds
to single digit nanoseconds. The
February 10, 2000
Telecommunications equipment continues to
drive faster and faster data rates and
bandwidths (levels approaching 1Tbps).
These high-speed systems must be
extremely reliable and demand that the data
they process meets this level of reliability
(five 9’s). Bus-type architectures, including
CompactPCI, provide the backbone for such
systems. Therefore, bused signal systems
operating within these requirements must
also assure that the data they carry is error
free, even during live insertion operations.
During the development and testing of these
systems, nanosecond discontinuities were
discovered with repeatability. Nanosecond
discontinuities are electrical
connects/disconnects occurring in the arena
of several nanoseconds to tens and hundreds
of microseconds. The electrical disruption
resulting from these intermittencies can
adversely affect certain systems.
Nanosecond discontinuities occur at the
initial point of closure between two highly
conductive separable interfaces. It is
primarily a result of the microscopic
1
04/20/00
Nanosecond Discontinuities & Quiet MateTM Contacts
phenomenon has been detected during both
engagement and disengagement operations.
- At the first break point (or beginning of the
nanosecond discontinuity), the hot-swap
card electrically separates from the running
bus, and continues to hold the energy it had
when the separation occurred. This energy
will leak off as a result of pre-charge or
other termination devices, but it is typically
subject to extremely slow time constants, as
a result of the high resistance value
associated with pre-charge elements.
- During the nanosecond discontinuity event,
the backplane bus may switch logic levels
(in the example, the bus transitions from
high to low). High-speed drivers will allow
this transition to occur as quickly as 1-2
nanoseconds, or possibly faster.
- Shortly after the bus transition, the
nanosecond discontinuity ends, and the hotswap card comes back in electrical contact
with the backplane bus. Two separate
voltage potentials come together at one
point.
- As a result, energy will immediately be
transferred to/from the daughtercard,
depending on relative potentials. This
energy transfer has the capability of
impacting a received/sampled signal
waveform significantly enough to result in
false data transfer.
Susceptible Systems
Hot-Swap Card
Slot 1
Slot 2
Slot X
• Bus Architectures
• Hot-Swap Capability
• High Fault-Tolerance Requirements
February 10, 2000
4
Specific systems which are susceptible to
nanosecond discontinuities are those which
have a ‘bused’ or ‘multi-drop’ architecture,
and possess the capability of hot-swapping
cards. An operating system requires that at
least one card is present and ‘driving’, with
a second (or additional) card(s) ‘receiving’,
when a third card is inserted into the system.
Typically, systems which require high faulttolerance operation will be more affected by
nanosecond discontinuities (as the
intermittencies tend to adversely impact
systems on a relatively infrequent basis).
Hot-Swap System Diagram
Detection of the Discontinuity
6.0
disengagement point
re-engagment point
5.0
Bus
Driver
4.0
bus signal above
receiver threshold
3.0
Voltage (V)
Receiver
Card
Hot-Swap
Card
Driver Card
Hot-Swap Card
Receiver Card
Data
Transition
Nanosecond
Discontinuity
Event
2.0
1.0
Pre-Charge
Established
0.0
1st Contact
1st Break
-1.0
2nd Contact
-2.0
0
5
5
10
15
20
Time (ns)
25
30
35
40
February 10, 2000
6
A simple timing diagram best illustrates the
worst-case impact of a nanosecond
discontinuity:
- At first contact between a hot-swap card
and the backplane, all waveforms coincide
(including the hot-plugged card), as all
pieces are connected electrically and
running.
February 10, 2000
An actual system waveform plot displays the
impact of a nanosecond discontinuity on a
sampled waveform. The additional
transferred energy boosts the level of the
signal above the threshold of the receiver
(blue line), and could result in a false
sampling of data.
2
04/20/00
Nanosecond Discontinuities & Quiet MateTM Contacts
the amount of time that the phenomenon can
exist and would reduce the probabilities of a
system detecting discontinuities. However,
since there is always an initial point of
contact, and since the inconsistencies occur
on the molecular level, probabilities are
decreased but not eliminated.
The final option is to limit the amount of
energy the daughtercard injects/absorbs
to/from the bus when the two metal surfaces
make electrical contact. One way of
approaching this is to lower the capacitance
on the daughtercard as much as possible.
Minimization of contact pads and other
metallic structures will reduce this
capacitance and effectively make the
daughtercard more inductive. However, this
reduction in capacitance can have an illeffect on the loading and timing of the bus,
especially since the reduction must occur on
all cards. In addition to signal integrity
concerns, the reduction in capacitance still
may not guarantee that the energy flow will
be reduced to an acceptable level. The
second option to reducing energy flow
during the mating sequence is to create a
resistive “shock absorber” between the
receptacle contact and the header pin, until
an acceptable normal force can be
established. This resistance would then be
invisible to an operating system (following
the live insertion event).
Nanosecond Discontinuity Impact
=> Nanosecond discontinuities
=> Energy transfer onto the bus
=> Signal Impact
Any conductive
hot-swap interface!!
7
February 10, 2000
Simulation and testing of hot-swap networks
has shown that nanosecond discontinuities
result in energy transferred onto or out of the
bus. Additional energy transferred to an
active bus has the potential of altering signal
levels. (Existing pull-up terminations are
ineffective during a nanosecond
discontinuity, due to their relatively slow
time constants.) Nanosecond discontinuities
can occur at any conductive hot-swap
interface at the near-zero normal force zone
that occurs at the very beginning of
engagement.
Solutions
• Software control during live insertion
• Decrease low normal force zone
• Limit rate of energy taken from the bus
– lower daughtercard capacitance
• physical restructuring
• impact on signal integrity and timing
Resistive Application
– add resistance during engagement
Unmated Receptacle and Pin
Resistive Coating
8
Pin
Receptacle
February 10, 2000
Final Engagement Position
Solutions to nanosecond discontinuities can
take several forms. The situation can be
controlled through software or hardware.
Software solutions are possible, but slow the
overall response of the system, thus a
hardware solution that does not slow the
system is preferred.
A decrease in the time of low normal force
mating would help to minimize
discontinuities. Stiffening backplanes and
pre-loading spring members help to decrease
Receptacle
9
Pin
February 10, 2000
The requirement of a guaranteed error-free
live insertion points to the application of a
resistive material on the pin as the best
solution. The material must exist on a
specific region of the pin. The material
3
04/20/00
Nanosecond Discontinuities & Quiet MateTM Contacts
must exist on the tip of the pin in any area
where the pin and receptacle could possibly
make first contact. The material must also
extend back far enough on the pin to assure
that sufficient normal force is obtained prior
to the receptacle sliding to and making
definitive contact with the gold surface of
the pin. Sufficient normal force guarantees
that the receptacle contact will not lose
electrical contact with the resistive material
or gold finish. The final resting position of
the pin is noted by the vertical dashed line.
Electrical simulations provide waveforms
showing an actual bus signal’s response to a
live insertion event, with the resistive
material present on the tip of the pin. The
resulting rate of current into the backplane
network is not enough to force the
continuously running data bus to cross the
thresholds of the detecting receiver.
Qualification Testing
• 2mm HM product spec (108-1622)
– 250 cycle durability
– pin staging
System Diagram Improved
• Bellcore GR-1217-CORE (Telcordia
(Telcordia))
– Mixed Flowing Gas (MFG)
– Temperature/Humidity
Data
Transition
Bus
Driver
• Resistance requirements
Receiver
Card
& Quiet Mate Contacts
Nanosecond
Discontinuity
Event
Hot-Swap
Card
12
Pre-Charge
Established
February 10, 2000
Hot-Swap Card &
Quiet Mate Contacts
1st Break
1st Contact
2nd Contact
The new resistive material has been tested to
the 2mm HM product specification (1081622) and qualified to the Bellcore GR1217-CORE (Telcordia) specification. The
pin continues to meet all specifications. The
durability of the new material exceeds the
already high (250 cycle) product
requirement. Pin staging requirements
continue to provide sequential mating, due
to the location of the resistive material. The
material is also being qualified, through
resistance profiles, to the required resistance
ranges specified by the simulations and
verification testing.
February 10, 2000
10
An adjusted timing diagram displays the
new behavior of a hot-swapped card, and the
resulting energy response seen at the input
of a sampling receiver device, when the
resistive pin tip is used. The total amount of
energy transferred is the same as before,
however the rate at which it is transferred is
much different. The reduced transfer rate
provides an impact at the receiver that no
longer can result in a false sampling of the
waveform data.
The Solution
6.00
disengagement point
re-engagement point
5.00
Driver Card
Hot-Swap Card
Receiver Card
4.00
gradual release
onto backplane
Voltage (V)
3.00
2.00
acceptable level
1.00
0.00
-1.00
-2.00
0.0
5.0
10.0
15.0
20.0
Time (ns)
11
25.0
30.0
35.0
40.0
February 10, 2000
4
04/20/00