Smart FET Robustness Testing 1 Agenda • Repetitive Clamp Testing • Repetitive Short Circuit Testing • Cold Bulb Testing • DV/Dt Testing 2 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 3 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) On Input Off Voltage Across DUT V(Br) VDD IAR Current Through DUT tav 4 Repetitive Clamping Test • A Gate to Drain Zener Clamp provides inductive flyback protection • Current through the clamp allows the device to turn on • Energy is dissipated through the channel as opposed to breaking down the body diode 5 Repetitive Clamping Test • 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 6 Repetitive Clamping Test • Measurements are taken periodically to insure that the repetitive clamping stress has not affected the parametric performance of the device. 54 RDSon (mOhm) 53 52 51 50 49 48 47 0 256k 1024k 2048k Readout NCV8403 RCL Drift Analysis VS=16V, 15A, 100µH, 145C Ta 48 VClamp (100µA) [V] 47.5 47 46.5 46 45.5 45 44.5 0 256k 1024k Readout 7 2048k 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 NCV8403 RCL Drift Analysis VS=16V, 15A, 100µH, 145C Ta 0.3 0.25 0.2 Ileak(28V) (µA) 55 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 0.15 0.1 0.05 0 0 256k 1024k 2048k Readout NCV8403 RCL Drift Analysis VS=16V, 15A, 100µH, 145C Ta 1.655 1.65 1.645 1.64 Vth (1mA) [V] NCV8403 RCL Drift Analysis VS=16V, 15A, 100µH, 145C Ta 1.635 1.63 1.625 1.62 1.615 1.61 1.605 0 256k 1024k Readout 2048k 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 1.10 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 2.10 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 Repetitive Short Circuit Testing (RSC) • 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 8 Repetitive Short Circuit Testing • The AEC Q100-12 specification describes tests for autorestart 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) 9 Repetitive Short Circuit Testing • 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 10 Repetitive Short Circuit Testing • 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 11 Repetitive Short Circuit Testing • Test Schematics and Load Conditions 12 Repetitive Short Circuit Testing • Long Pulse Example Waveforms -40 C 13 25 C Repetitive Short Circuit Testing • Long Pulse Weibull Plot – Shows ppm levels for given number of short circuit cycles Weibull Plot - NCV8403 LSC (-40C, 25C) -40C 25C Power (-40C) Power (25C) 100.0000 1 ppm fail rate Cumulative Failures (%) 10.0000 1.0000 0.1000 First room failure at 48 k cycles 0.0100 First cold failure at 14 k cycles 0.0010 0.0001 1 10 100 1000 Cycles to Failure 14 10000 100000 1000000 Cold Bulb Testing (CBT) • 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 15 Cold Bulb Testing • Cold Bulb Test – – – – – 16 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 • Test Schematic 17 Cold Bulb Testing • Step 1: Preconditioning 30 sec. Continuous (Hot) RSC Test Example Waveform 18 Cold Bulb Testing • Step 2: Preconditioning Repetitive Short Circuit- Long Pulse Example Waveform 19 Cold Bulb Testing • Step 3: Cold Bulb Test Example Waveform 20 Cold Bulb Testing • Step 3: Cold Bulb Test Results – Parametrics periodically monitored to ensure the devices are within spec 21 DV/Dt Testing •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-stressed Transistor 22 DV/Dt Testing •Test setup that produces fast voltage transients and has been used to induce damage on the bench. Fast Voltage transient on Drain 23 DV/Dt Testing •Test Schematic •Z-Test- Used to verify the robustness of our new designs 24 DV/Dt Testing •Test Results- Z Test •Redesigned NCV portfolio withstood 50 fast transient pulses with zero device failures Z-Test Survival Rate (50 pulses) 120 100 80 Survival Rate (%) 60 Sample Size 40 20 0 NID5001 25 NIF5002 NIF5003 New 5003 (NCV8403) DV/Dt Testing •Test Schematic •IEC Pulse Tester Used to characterize Robustness of new designs 26 DV/Dt Testing •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 Experiment with Self-Protected FET -- IEC Pulse on Biased Drain (Vgs = 0 V) 100,000 IEC Pulse Voltage (V) at Last Pass 30 kV Max 10,000 NIF5002 NIF62514 Fix NIF62514 No Fix 1,000 NCV8403 NIF5003 NID5001NT4 NCV8401 100 10 5 15 25 Vds Bias Voltage (V) 27 35 45 Conclusions • 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 28 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 29