Smart FET Robustness Testing.ppt [Read-Only]
Transcript of Smart FET Robustness Testing.ppt [Read-Only]
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Smart FET Robustness Testing
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Agenda
• Repetitive Clamp Testing
• Repetitive Short Circuit Testing
• Cold Bulb Testing
• DV/Dt Testing
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Repetitive Clamping Test (RCL)• The purpose of this test is to determine the repetitive
inductive avalanche switching capability of power devices.
• The RCL test is an endurance test which verifies the effectiveness of the load flyback protection over the device lifetime
• This test establishes the load current versus inductance curve for the device
• Test is based on JESD24-8 Standard
Insert representative power curve here as an example
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Repetitive Clamping Test• Energy delivered must drive the device to a peak
temperature of TJmax during test• Device must be avalanched and survive the customer
required number of avalanche events (Typically 1-2 million cycles)
Input
Voltage Across DUT
Current Through
DUT
On
Off
V(Br)
VDD
IAR
tav
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Repetitive Clamping Test
• A Gate to Drain Zener Clamp provides inductive flybackprotection
• Current through the clamp allows the device to turn on• Energy is dissipated through the channel as opposed to
breaking down the body diode
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• Current is ramped up in the inductor and goes to ground through a resistor
• Once the current reaches the required level, the switch is opened
• The DUT then goes into avalanche as the inductor flies back
Repetitive Clamping Test
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• Measurements are taken periodically to insure that the repetitive clamping stress has not affected the parametric performance of the device.
NCV8403 RCL Drift AnalysisVS=16V, 15A, 100µH, 145C Ta
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0 256k 1024k 2048kReadout
RD
Son
(mO
hm)
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NCV8403 RCL Drift AnalysisVS=16V, 15A, 100µH, 145C Ta
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Ileak
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NCV8403 RCL Drift AnalysisVS=16V, 15A, 100µH, 145C Ta
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Readout
VCla
mp
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µA) [
V]
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NCV8403 RCL Drift AnalysisVS=16V, 15A, 100µH, 145C Ta
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Readout
Vth
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A) [
V]
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Repetitive Clamping Test
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• The purpose of this test is to determine the reliability of protected drivers when operating in a continuous short circuit condition
• The results of this test predict the survivability of a device under short circuit conditions (e.g. Weibull Plot)
• RSC testing is detailed in AEC Q100-12 Specification
Repetitive Short Circuit Testing (RSC)
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• The AEC Q100-12 specification describes tests for auto-restart and latched devices
• Our current product portfolio falls into the auto-restart category
• The specification describes 2 main test types– Long Pulse (-40 C & 25 C)– Continuous (Hot RSC)
Repetitive Short Circuit Testing
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• Long Pulse Testing– Test is run at -40 C and 25 C– Device under test is place into a short circuit for 300 ms– Device must cool down to ambient between test pulses– Pulses continue until one of 2 conditions are met
• 50% of the population has failed (parametric, or gross failure)• 100,000 cycles are met with 0 failures
Repetitive Short Circuit Testing
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• Continuous (Hot) Repetitive Testing– Test is run at 25 C ambient– Device under test is placed into a continuous short circuit– Device toggles in and out of Thermal Shutdown– Pulses continue until one of 2 conditions are met
• 50% of the population has failed (parametric, or gross failure)• 100 hours have elapsed with 0 failures
Repetitive Short Circuit Testing
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• Test Schematics and Load ConditionsRepetitive Short Circuit Testing
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• Long Pulse Example Waveforms
-40 C 25 C
Repetitive Short Circuit Testing
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• Long Pulse Weibull Plot– Shows ppm levels for given number of short circuit cycles
Weibull Plot - NCV8403 LSC (-40C, 25C)
0.0001
0.0010
0.0100
0.1000
1.0000
10.0000
100.0000
1 10 100 1000 10000 100000 1000000
Cycles to Failure
Cum
ulat
ive
Failu
res
(%)
-40C 25C Power (-40C) Power (25C)
Repetitive Short Circuit Testing
1 ppm fail rateFirst cold failure at 14 k cycles
First room failure at 48 k cycles
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• This test is used to determine the bulb inrush current survivability
• Example test sequence– Step 1: Preconditioning 30 sec. Continuous (Hot) RSC– Step 2: Preconditioning Repetitive Short Circuit- Long Pulse
• 100 cycles, 25 C– Step 3: Cold Bulb Test
Cold Bulb Testing (CBT)
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• Cold Bulb Test– Bulb Load in -40 C chamber– V(supply) = 15 V– DUT held at room temperature– DUT turned on 100,000 times with load connected– DUT on until bulb current stabilizes (200 ms), off until bulb returns to
-40 C
Cold Bulb Testing
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• Test SchematicCold Bulb Testing
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• Step 1: Preconditioning 30 sec. Continuous (Hot) RSC Test Example Waveform
Cold Bulb Testing
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• Step 2: Preconditioning Repetitive Short Circuit- Long Pulse Example Waveform
Cold Bulb Testing
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• Step 3: Cold Bulb Test Example Waveform
Cold Bulb Testing
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• Step 3: Cold Bulb Test Results– Parametrics periodically monitored to ensure the devices are within spec
Cold Bulb Testing
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•DV/Dt testing is done to verify the devices ability to survive fast transients
•Fast transients have been shown to cause damage in Protected FET’s
Over-stressedTransistor
DV/Dt Testing
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•Test setup that produces fast voltage transients and has been used to induce damage on the bench.
Fast Voltage transient on Drain
DV/Dt Testing
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•Test Schematic•Z-Test- Used to verify the robustness of our new designs
DV/Dt Testing
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Z-Test Survival Rate (50 pulses)
0
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4060
80
100
120
NID5001 NIF5002 NIF5003 New 5003(NCV8403)
Survival Rate (%)Sample Size
•Test Results- Z Test•Redesigned NCV portfolio withstood 50 fast transient pulses with zero device failures
DV/Dt Testing
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•Test Schematic•IEC Pulse Tester Used to characterize Robustness of new designs
DV/Dt Testing
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Experiment with Self-Protected FET -- IEC Pulse on Biased Drain (Vgs = 0 V)
10
100
1,000
10,000
100,000
5 15 25 35 45
Vds Bias Voltage (V)
IEC
Pul
se V
olta
ge (V
) at L
ast P
ass
NIF5002NIF62514 FixNIF62514 No FixNCV8403NIF5003NID5001NT4NCV8401
30 kV Max
•Test Results- IEC Pulse Tester•Redesigned NCV portfolio withstood 30 kV transients with up to 40 V on the Drain•Old NIF/NID portfolio failed with <30 kV transients
DV/Dt Testing
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• ON Semiconductor NCV Smart FET devices are characterized with the following tests:– Repetitive Clamp Testing
• Determines the repetitive inductive avalanche switching capability of power devices.
– Repetitive Short Circuit Testing• Determines the reliability of protected drivers when operating in a
continuous short circuit condition– Cold Bulb Testing
• Determines the bulb inrush current survivability– DV/Dt Testing
• Verifies the devices ability to survive fast transients
Conclusions
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For More Information
• View the extensive portfolio of power management products from ON Semiconductor at www.onsemi.com
• View reference designs, design notes, and other material supporting automotive applications at www.onsemi.com/automotive