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(TLP) Overview 1. What is TLP 2. How TLP works 3. TLP measurement - PowerPoint PPT Presentation

Mar 31, 2024 •654 likes •1.39k views

Introduction to Transmission Line Pulse (TLP) Overview 1. What is TLP 2. How TLP works 3. TLP measurement 4. TLP variants 5. Interpreting TLP data 6. TLP Precision 7. VF-TLP 8. Q&A 2 History Transmission Line Pulse

  1. Introduction to Transmission Line Pulse (TLP)

  2. Overview 1. What is TLP 2. How TLP works 3. TLP measurement 4. TLP variants 5. Interpreting TLP data 6. TLP Precision 7. VF-TLP 8. Q&A 2

  3. History • Transmission Line Pulse • Introduced as a possible method to emulate energy in HBM • Determined that for a given peak current, a TLP pulse of 100ns carries the same energy as HBM • Same energy is produced by different voltages:  50V TLP = 1A -50 0 50 100 150 200 250  1500V HBM = 1A 3

  4. Background • Characterization of protection structures is important • Predict behavior for real world events • Important parameters: • Snapback voltage • Turn on time • R ON resistance • Failure point • Must determine parameters with techniques similar to ESD • TLP is an excellent solution • Controlled impedance makes measurements easier • Low duty cycle prevents heating 4

  5. Section 1 What is TLP 5

  6. Section 1: What is TLP TLP Waveform • What makes TLP different than ESD ? Voltage • ESD tests simulate real world events • HBM, MM, IEC, CDM • TLP does not simulate any real-world event -20 0 20 40 60 80 100 120 T ime (ns) • ESD tests record failure level • “Qualification” • TLP tests record failure level and device behavior • “Characterization” 6

  7. Section 1: Device Characterization  What is Device Characterization? • Describes the resistance of a device for a given stimulus • Resistance = Voltage / Current • Conventionally performed by increasing amplitude until failure 2.9 2.4 1.9 I DU T (A) 1.4 0.9 0.4 -0.1 • Like Curve Tracing 0 5 10 15 V D U T (V) 7

  8. Section 1: Device Characterization  How is TLP different than Curve Tracing? • Curve Tracing is DC • TLP is a short pulse Voltage Voltage Time Time • Shorter pulse • Reduced duty cycle, less heating • Controlled Impedance • Allows device behavior to be observed (more on this later) 8

  9. Section 1: Device Characterization • How is TLP the same as Curve Tracing? TLP DC Curve Trace Voltage Voltage Time Time • Measure resistance of device with increasing voltage • Less heat means higher voltage before failure 9

  10. Section 1: Device Characterization • What can I learn from Device Characterization with TLP ? • Turn-on time 0.45 0.4 0.35 0.3 I DUT (A) • Snapback voltage 0.25 0.2 0.15 0.1 • Performance changes with rise time 0.05 0 0 2 4 6 8 10 12 V DU DUT (V) 10

  11. Section 1: TLP Waveforms  What does a TLP waveform look TLP Waveform like? Voltage • Square pulse -20 0 20 40 60 80 100 120 T ime (ns) • Unlike ESD waveforms, TLP does not mimic any real world event HBM Waveform MM Waveform 11

  12. Section 1: TLP Waveforms  What variations are there for TLP waveforms? TLP Waveform • Pulse Width Voltage • 100ns Pulse Width • 30ns – 500ns • VF-TLP: 1ns – 10ns -20 0 20 40 60 80 100 120 T ime (ns) TLP Waveform TLP Waveform • Rise Time • 0.2ns – 10ns Voltage Voltage Rise Time Rise Time -20 0 20 40 60 80 100 120 -20 0 20 40 60 80 100 120 Time (ns) Time (ns) 12

  13. Section 1: TLP Waveforms  How do these variations affect the TLP test? Voltage • Pulse Width • Energy under the curve Pulse Width -20 0 20 40 60 80 100 120 Time (ns) • Rise Time Voltage • Device reaction Rise Time -20 0 20 Time (ns) 13

  14. Section 1: Devices for TLP Testing • What kinds of packages can be tested? • Package Level • Wafer Level 14

  15. Section 2 How TLP Works • How TLP pulses are generated 15

  16. Section 2: How TLP Works • How is a TLP waveform generated? • Transmission Line connected to power supply • Called Charge Line • Length proportional to pulse width • Power supply charges the cable 16

  17. Section 2: How TLP Works • How is a TLP waveform generated? • DUT lies at end of another transmission line • Switch closes • Charge exits Charge Line , propagates towards DUT 17

  18. Section 2: How TLP Works  How is a TLP waveform generated? • Square waveform • Charge Line behaves as a storage device Voltage -20 0 20 40 60 80 100 120 Time (ns) 18

  19. Section 2: How TLP Works • What happens when the waveform hits the DUT? • Recap: TLP is a short-duration pulse in a controlled-impedance environment • Behaves like an RF signal • RF signal behavior • Propagates until impedance changes 19

  20. Section 2: How TLP Works • How is resistance measured with a TLP pulse? • Square pulse, perceive it as a short-duration Curve Trace TLP DC Curve Trace • Voltage and Current probes measure the DUT 20

  21. Section 2: How TLP Works  How is resistance measured with a TLP pulse? • Plateau of waveforms are averaged • Device allowed to settle into “quasi - static” state Current Probe Waveform Voltage Probe Waveform Voltage Current -20 0 20 40 60 80 100 120 -20 0 20 40 60 80 100 120 Time (ns) Time (ns) 21

  22. Section 2: How TLP Works • Why use both a Voltage probe and a Current probe? Current Probe Waveform Voltage Probe Waveform Current Voltage -20 0 20 40 60 80 100 120 -20 0 20 40 60 80 100 120 Time (ns) Time (ns) • It is possible to calculate DUT resistance with only 1 probe • V DUT = V Pulse – (I DUT * Z TLP ) • I DUT = (V Pulse – V DUT ) / Z TLP • Not desirable because extremes are noisy 22

  23. Section 2: How TLP Works  Sequential TLP pulses produces an I/V Curve OPEN Circuit SHORT Circuit 0 .6 1.9 0 .5 I DUT (A) 1.4 I DUT (A) 0 .4 0 .3 0 .9 0 .2 0 .4 0 .1 - 0 .1 0 0 5 10 15 2 0 2 5 3 0 0 0 .2 0 .4 0 .6 0 .8 1 V DUT (V) V DUT (V) Resistor Snapback Device 0.3 0 .4 5 0 .4 0.25 0 .3 5 I DUT (A) I DUT (A) 0.2 0 .3 0.15 0 .2 5 0 .2 0.1 0 .15 0.05 0 .1 0 .0 5 0 0 0 5 10 15 20 25 30 0 2 4 6 8 10 12 V DUT (V) V DUT (V) 23

  24. Section 2: How TLP Works • How is the Pulse Width changed? • Length of cable  How is the Rise Time changed? • Low-pass filter added LP 24

  25. Section 3 TLP Measurement • How devices are measured 25

  26. Section 3: TLP Measurement • Measurement Goals • Capture Voltage at the DUT • Capture Current through the DUT 26

  27. Section 3: TLP Measurement • Equipment to capture V and I Voltage Probe Oscilloscope Current Probe 27

  28. Section 3: TLP Measurement • Equipment to deliver TLP pulse to DUT Wafer Level 1. DUT (on wafer) 2. TLP Pulse delivery cable 3. TLP Pulse delivery probe 4. Ground Probe 3 5. Ground Braid 2 5 1 Package Level 1. DUT in socket 2. TLP Pulse delivery cable 3. Grounded pin 3 4 28

  29. Section 3: TLP Measurement • Ideally, V and I probes are directly on DUT • Direct placement not possible V/I Probes 29

  30. Section 3: TLP Measurement • Although probes are not at DUT, measurements are possible V/I Probes • Controlled impedance • Waveform observable any place along path • Time Domain Reflection (TDR) 30

  31. Section 3: TLP Measurement • How are measurements accomplished away from DUT? V/I Probes • Incident and Reflected waveforms • Adding the waveforms reproduces DUT measurement • Incident and Reflected waveforms are recorded separately (TDR-S) 31

  32. Section 3: TLP Measurement Reflected DUT Ω > Z TLP DUT Ω < Z TLP DUT Ω = Z TLP Waveform (Example: 50 Ω Resistor) (Example: Open Circuit) (Example: Short Circuit) Polarity Negative Reflection No Reflection Positive Reflection Voltage Waveform No Reflection Negative Reflection Positive Reflection Current Waveform 32

  33. Section 3: TLP Measurement • TDR-S performs waveform addition with software V/I Probes  Waveform addition can also be done in the TLP circuit V/I Probes 33

  34. Section 3: TLP Measurement • Overlapping waveforms V/I Probes • Incident and Reflected overlap, add together • Overlapped waveform plateau reproduces DUT waveform 34

  35. Section 4 TLP Variants 35

  36. Section 4: Importance of Impedance  Why vary the impedance? • Low Impedance • More current flow for a given voltage • More voltage amplitude • High Impedance • Less current flow for a given voltage • Less voltage amplitude 36

  37. Section 4: TLP Variants • TLP circuit characteristics up to this point • 50 Ω Impedance • One stress-pin • One ground-pin Incident Pulser Reflected D U • Time Domain Reflection (TDR) Absorbed T V and I to • TDR-O Scope • TDR-S • Variations alter the system impedance and grounding style 37

  38. Section 4: TLP Variants • Time Domain Transmission (TDT) • 25 Ω system impedance Incident Scope Ch3 Pulser Transmitted Reflected D U Absorbed T V and I to Scope 38

  39. Section 4: TLP Variants • Time Domain Reflection and Transmission (TDR-T) • DUT in series with pulse transmission path • 100 Ω Impedance Incident Scope Ch3 Pulser DUT Reflected Absorption Transmitted V and I to Scope 39

  40. Section 4: TLP Variants • High-Z Time Domain Reflection and Transmission (TDR-T) • DUT in series with pulse transmission path • 500 Ω , 1k Ω Impedance High-Z Ω Incident Scope Ch3 Pulser DUT Reflected Absorption Transmitted V and I to Scope 40

  41. Section 5 Interpreting TLP Data 41

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