Driving Down Test Cost, Agilent Technologies Schedule and ... · #1 - Automated test strategies...
Transcript of Driving Down Test Cost, Agilent Technologies Schedule and ... · #1 - Automated test strategies...
Agilent Technologies ©
Webcast Series
Spring, 2012
Driving Down Test Cost,
Schedule and Risk
With a Smart Approach
to Switching
Agilent Technologies
Software and Modular Solutions
Division
Mark Bailey
Product Marketing Manager
May 30th, 2012
Agilent Technologies ©
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Agilent Technologies ©
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Driving Down Test Cost, Schedule & Risk
with a Smart Approach to Switching
#1: Automated test topologies – choosing the right one
#2: Switch types – choosing the right switches and protection
#3: Switch topologies – Getting the most from your switches
#4: Switching Power Supplies and Loads – what to watch for
#5: Grounding and noise in your switch systems – getting it right
#6: Switching Example: Testing Automotive Electronic Control Units (ECUs)
#7: Using a Web Interface to set up and monitor your switching system
- Equipment Cost
- Test Speed
- Development Time
- Measurement Integrity
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MUX
Switch
DMM
“Functional Test”
- Transactional
“Data Acquisition”
- Scanning
Two Basic Switch Applications
Matrix – can connect multiple DUT
points to various instruments
• Close relay
• Change instrument function
• Trigger measurement
• Return results
• Open relay
MUX – can connect one of many DUT
points to a single instrument • Close relay
• Take Measurement
• Close relay
• Take Measurement
• Close relay …etc.
PS
SA
Counter
Arb
DMM
Sig Gen Matrix
Switch DUT
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Functional test plans are switching intensive
Case study: Engine ECU testplan
Number of transactional communications
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#1 - Automated test strategies
Application emulation mode
– Tests full operation- hardware & firmware
– Slowest testing
– Difficult to leverage
– Emulation test methodology
DUT Assisted Test (DAT)
– Fastest method for high volume test
– Most Common & Most Reusable
– Embedded test code required
– Transactional test methodology
Application Emulation -
commonly used in
development or burn-in
testing
Design Assisted Test -
commonly used in
manufacturing test
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Automated test topologies for Speed of Test
Application test mode vs. DUT assisted test mode
Application Emulation Test
- Targeted for application DUT Assisted Test
- Optimizes flexibility
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Automated test topologies
• Measurement Matrix
Connect Instruments to DUT
1-, 2-, and 4-wire connections
• RF/µWave Switching
High frequency path
Multichannel
• Multi-channel Disconnect
Reduced loading
Consolidate measurements
• Load and Power
Simulate loading
Apply power to DUT
Automated systems are
constructed from
part or all of these
sections
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Electromechanical Armature Relays
• Rugged, supports higher currents and voltages
• Low On-Resistance (< 1Ω)
• Slower switch speeds
Reed Relays
• High-speed switching
• Very low contact resistance
• Long mechanical life if not overstressed
FET Switches
• High-speed switching
• Higher “on resistance” (Typically 100 Ω)
• Low voltage/current handling capability
• Doesn’t provide “Voltaic Disconnect”
Armature
Reed
FET
# 2 - Switch Technology
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Relay Life Spans
Life span of relays affected by:
• Types of loads being switched
• High-power or high-voltage switching
• Resistance of relay contactss
Maximize relay lifetime:
• Always maintain signal within relay’s voltage/current ratings
• Avoid “hot switching”
• Use surge-suppression circuits
– Resistor in series with capacitive load
– Zener diode in parallel with inductive load
Load Type Derated
lifetime*
Resistive 75%
Inductive 40%
Capacitive 75%
Motor 20%
Incandescent 10%
* Of manufacturer specification
Slide 9
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Agilent Technologies ©
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TIP: Limit surge current for longer reed relay life
Load Life Operations
10 V / 4 mA 100 Million
7.5 V / 150 mA 20 Million
1 V / 1 mA 500 Million
10 V / 50 mA 50 Million
120 V / 1 mA 5 Million
55 V / 11 mA 5 Million
30 V / 20 mA 15 Million
5 V / 500 mA 0.4 Million
Example reed relay data
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#3 - Switching Topologies - General Purpose Switches
Simple Relay Configurations
• 3 common configurations
• Most often used for simple on/off
switching of power
• Can be linked together
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Agilent Technologies ©
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Switching Topologies - Multiplexers
Single-Wire Multiplexers
• Useful for common-low applications
Two-Wire Multiplexers
• Useful for floating measurements
Four-Wire Multiplexers
• Useful for four-wire
resistance measurements
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A Matrix is used to connect multiple points at
one time
• Widely used in functional test applications
• Can reconfigure on-the-fly
• Can connect power, stimulus and
measurement at one time
• Cautions
– Possible to accidentally connect sources
together
– More wires, more susceptible to noise and
crosstalk
In
stru
ments
DU
T p
oin
ts Switching Topologies - Matrix
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Examples of Switching Systems
Pro
duct F
lexib
ility
High
Low
Just Enough
Performance:
Up to 60 channels,
3 slots, 8 modules
Higher Level
Performance:
Up to 560 channels,
8 slots, 21 cards
Balanced Throughput &
Performance:
High Density,
High Speed,
Many modules
34980A Multifunction Switch
Measure Unit
34970A/72A Data Logger
Price Performance Decision Criteria
M9000-series
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RF / Microwave Switching Systems
1) Modules for 34980A:
For systems requiring both low and high frequency
switching, controlling multiple switch matrices
• 34941A/42A Quad 1x4 switch to 3GHz
• 34946A/47 2/3 SPDT switches to 26.5GHz
• 34945A/EXT uW switch driver
2) L4445A/EXT External Switch Driver:
For standalone switch driver to control
Switches, Couplers Attenuators, dividers
in the fixture
3) L4490A/91A RF Switch Platform:
2U or 4U high enclosure includes uW switch
driver, power, drivers and space to mount
switches
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True X-Y Matrix Configuration
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Matrix in X by Y by Z Configuration –
Reduces Cross Points & Saves Space and Money
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Example High Density Matrix Module
Best solution:
Protection resistors with bypass relays
• Limits surge currents
• Bypass relays used when providing light duty stimulus or for low level measurements
Row disconnect relays
• Reduces loading capacitance as matrix size increases
Agilent 34934A 512 Cross-Point Matrix with flexible configurations
Four 4x32 blocks
- 1-wire: 4x128, 8x64, 16x32
- 2-wire: 4x64, 8x32
Row
disconnect
Bypass
relays
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Helpful hint: Matrix x structure
2 wire matrix structures provide good noise and bandwidth performance.
But in cases were two or more instruments need to be stacked, 2-Wire
matrix structures make that hard to do.
Problem:
Solution: Build a matrix X structure into your switching to allow
stacking of isolated instruments and signal inversion.
Stacked Inversion
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Cabling in Switching Systems
May need to run several meters to DUT
HINT: Twisted pair improves BW and reduces noise
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Two nodes are adjacent if there is only one switching
element connecting them. They are NOT adjacent if
more than one switching element connects them.
A is only adjacent to B
B is adjacent to A, C, and D
(etc.)
A
D
F
C
E
B
A is not adjacent to C, D, E or F
B is not adjacent to E or F
Switching Element
• A switching path is an ordered set of adjacent nodes
Possible switch paths are:
[A | B | C]
[A | B | D | F]
(etc.)
Switching Nodes and Paths
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Watch for Resistance in Test System
• Cable & Matrix resistance can add to overall
measurement error
• Use 4 wire resistance measurement for
improved accuracy especially for measuring
low resistances.
• Minimum of 4 wire analog bus is required for
4 wire resistance measurements
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How to select the right mux/matrix card(s)
1. How many signals need to be applied and/or measured with different instruments at the same time? (Calculate how many analog busses and/or banks will be needed)
2. How many total points are there that will ever need to be connected to any instrument? (Tells you how many channels you need; 20, 40, 70, etc.)
3. What kind of accuracy is required? (Tells you if you need 1-wire, 2-wire or 4-wire configuration)
4. What voltage and current rating is needed? (note that switch current is different from carry current)
5. Is current measurement needed?
6. How fast do the readings need to be?
7. Are non-DC signals being switched? If so, what is the highest frequency?
Application Note: Tips for Optimizing Your Switch Matrix Performance 5990- 4855EN
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Switching Topology Summary
– Testing methodology: DUT Assisted Test vs. Full Functional Test
– Single vs. dual wire switching systems
– High Density Matrix with multiple analog bus lines allows flexible
interconnect from instruments to Device Under Test (DUT)
– Relay technologies - choose appropriate relays:
• Armature relays for robust switching of higher voltages and currents
• Reed relays for fast measurement switching
• FET relays for unlimited switching lifecycle
– Use current limit resistance to extend cycle-life
of reed relays. Use bypass relays when need
to source current through matrix
– Use twisted pair for best BW and
noise performance
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# 4 - Load and
Power Switching
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Load and Power Switching
• Required to properly stress
unit and simulate real life
• Multiple configurations
– High-side
– Low-side
– Multiplexed loads
– Bridge loads
• Use external load tray as
part of system or in fixture
• Switched loads allow
parametric measurements
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Load management methods
Use load tray for high powered loads
Power Bus 1 (PB1) GND
Power Bus 2 (PB2) Vbatt
Load tray structure located
either in test system or fixture
expand PBx
as needed
to DMM or digitizer
via meas matrix
Switching
measurement
matrix
To power supply(+)
(-)
Current shunt R
~0.05 ohm typically
current limiting resistors
180 180
180 180
180 180
over-current
protection if required
Device
Under Test
(DUT)
*
* special case; in event of very
high currents can use fixture
mounted disconnect.
Load tray example
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Power supply remote sense
Remote sense to remove V drop under load
Need to choose one location to sense
• at power bus in load tray -or-
• at DUT
Be careful about switching remote sense!
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Summary…
Power supplies and load trays:
• Use central load tray with power bus to manage high
power loads
• Resistive power shunts can be used to monitor currents
through loads – locate close to actual load
• Selectively place protection in-line to product tester in
event of defective DUT
• Power supply remote sensing, need to decide location
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(“STAR” Ground)
#5 - System Grounding Recommendations
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Source: "Noise Reduction Techniques in Electronic Systems“ by Henry W. Ott
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System Grounding Recommendations
Test System Ground Is Floating
Power Supply Grounds are Floating
UUT Ground Floats
Recommendation:
– At UUT, Tie System Ground and Power
Supply Grounds to UUT Ground
– Typically Reference these to Earth at UUT
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#6 - Automotive Applications
Testing of automobile electronics
Power Train (ECU, TCU)
Body Electronics (BCU, RKE)
Telematics / Infotainment
Automotive sensors
Safety:
• Air bags,
• ABS,
• Collision avoidance
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Testing Multiple ECUs simultaneously
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Agilent 34980A Switch/Measure Unit
- 8 slots, up to 560 channels
- 21 modules available
- Universal inputs with 300 V switching
- Easy front panel operation for setup and debug
- Built-in DMM with 1000 readings/second
- Can hot-swap modules
- LAN, GPIB and USB and LAN with Web interface
- Terminal blocks for easy connect/disconnect
- As much as 40% lower cost than PXI
Application Note 5989-5852EN: Comparing the Agilent 34980A and PXI
for Switch Measurement Applications
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Agilent 34980A Switch/Measure Unit Switch Cards
Slide 35
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Engine Control Unit Test Using
the 34980A Switch/Measure Unit
• Use the 34980A DACs to
source control pins, matrix
cards to route signals to
measurement equipment, GP
switches to switch supplies
and the internal DMM for
measurements
•34980A 4-wire Analog bus for
exceptional signal routing
Configuration:
34980A with 6 ½ digit DMM
34951A D/A Converter
34937A GP switch
34933A 1-wire matrix
34952A multifunction module
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#7 - 34980A Web Server - Multiplexer
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34980A Web Server - Matrix
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34980A Web Server - GP Switches
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Switching Solutions Available from Agilent
Bench and System Switching Products Catalog 5989-9872EN
Slide 40
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We’ve talked about the following:
Selecting the best test topology for your application
Switch types and configurations – Armature, Reed, Mux, Matrix, etc.
Considerations for switching power supplies and loads
Grounding concerns and recommendations
Benefits of an instrument’s built-in web server
Plan up front, and you will reduce risk
while saving time and money.
Driving Down Test Cost, Schedule & Risk
with a Smart Approach to Switching
41
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Agilent Technologies ©
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Purchase a 34980A Multifunction Switch/Measure System
between May 1 and September 30, 2012 –
Get BenchLink Data Logger Pro Software FREE !!
(… A $1,000 USD Value…)
Here’s how:
1. Purchase a 34980A Switch/Measure system
2. Visit web site www.agilent.com/find/34980promo
3. Enter personal information & 34980A serial number
BenchLink Data Logger Pro software certificate and key will be emailed to the customer.
Customer uses the key to enable the BenchLink Data Logger Pro, shipped on a CD with the 34980A, to operate continuously with full capability.
Special Offer on BenchLink Data Logger Pro
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1. Find out more: www.agilent.com/find/34980switch
2. Watch the 34980A in Action on YouTube
3. Get a Quick Quote
4. Contact a Distribution partner
Thank you for attending !! Questions??
Buy from an
Authorized Distributor
www.agilent.com/find/distributors
20 March 2012 Recorded Focus on Sensors: How to make fast, reliable
sensor measurements with your data logger system
30 May 2012 Recorded Focus on Switching: Multiplexers, Matrices and
System Performance
13 July 2012 11:00 AM MDT Focus on Control: Digital and Analog Control Tips
and Techniques
06 Sept 2012 11:00 AM MDT Focus on Data Acquisition: Setup, Programming,
Debugging and Maintaining a Reliable System
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