SLAA530B March   2012  – July 2021 MSP430F5131 , MSP430F5132 , MSP430F5151 , MSP430F5152 , MSP430F5171 , MSP430F5172 , MSP430F5212 , MSP430F5214 , MSP430F5217 , MSP430F5219 , MSP430F5222 , MSP430F5224 , MSP430F5229 , MSP430F5232 , MSP430F5234 , MSP430F5237 , MSP430F5239 , MSP430F5242 , MSP430F5244 , MSP430F5247 , MSP430F5249 , MSP430F5252 , MSP430F5253 , MSP430F5254 , MSP430F5255 , MSP430F5256 , MSP430F5257 , MSP430F5258 , MSP430F5259 , MSP430F5304 , MSP430F5308 , MSP430F5309 , MSP430F5310 , MSP430F5324 , MSP430F5325 , MSP430F5326 , MSP430F5327 , MSP430F5328 , MSP430F5328-EP , MSP430F5329 , MSP430F5333 , MSP430F5335 , MSP430F5336 , MSP430F5338 , MSP430F5340 , MSP430F5341 , MSP430F5342 , MSP430F5358 , MSP430F5359 , MSP430F5418 , MSP430F5418A , MSP430F5419 , MSP430F5419A , MSP430F5435 , MSP430F5435A , MSP430F5436 , MSP430F5436A , MSP430F5437 , MSP430F5437A , MSP430F5438 , MSP430F5438A , MSP430F5438A-EP , MSP430F5500 , MSP430F5501 , MSP430F5502 , MSP430F5503 , MSP430F5504 , MSP430F5505 , MSP430F5506 , MSP430F5507 , MSP430F5508 , MSP430F5509 , MSP430F5510 , MSP430F5513 , MSP430F5514 , MSP430F5515 , MSP430F5517 , MSP430F5519 , MSP430F5521 , MSP430F5522 , MSP430F5524 , MSP430F5525 , MSP430F5526 , MSP430F5527 , MSP430F5528 , MSP430F5529 , MSP430F5630 , MSP430F5631 , MSP430F5632 , MSP430F5633 , MSP430F5634 , MSP430F5635 , MSP430F5636 , MSP430F5637 , MSP430F5638 , MSP430F5658 , MSP430F5659 , MSP430F6433 , MSP430F6435 , MSP430F6436 , MSP430F6438 , MSP430F6458 , MSP430F6459 , MSP430F6459-HIREL , MSP430F6630 , MSP430F6631 , MSP430F6632 , MSP430F6633 , MSP430F6634 , MSP430F6635 , MSP430F6636 , MSP430F6637 , MSP430F6638 , MSP430F6658 , MSP430F6659 , MSP430F6720 , MSP430F6720A , MSP430F6721 , MSP430F6721A , MSP430F6723 , MSP430F6723A , MSP430F6724 , MSP430F6724A , MSP430F6725 , MSP430F6725A , MSP430F6726 , MSP430F6726A , MSP430F6730 , MSP430F6730A , MSP430F6731 , MSP430F6731A , MSP430F6733 , MSP430F6733A , MSP430F6734 , MSP430F6734A , MSP430F6735 , MSP430F6735A , MSP430F6736 , MSP430F6736A , MSP430F6745 , MSP430F67451 , MSP430F67451A , MSP430F6745A , MSP430F6746 , MSP430F67461 , MSP430F67461A , MSP430F6746A , MSP430F6747 , MSP430F67471 , MSP430F67471A , MSP430F6747A , MSP430F6748 , MSP430F67481 , MSP430F67481A , MSP430F6748A , MSP430F6749 , MSP430F67491 , MSP430F67491A , MSP430F6749A , MSP430F67621 , MSP430F67621A , MSP430F67641 , MSP430F67641A , MSP430F6765 , MSP430F67651 , MSP430F67651A , MSP430F6765A , MSP430F6766 , MSP430F67661 , MSP430F67661A , MSP430F6766A , MSP430F6767 , MSP430F67671 , MSP430F67671A , MSP430F6767A , MSP430F6768 , MSP430F67681 , MSP430F67681A , MSP430F6768A , MSP430F6769 , MSP430F67691 , MSP430F67691A , MSP430F6769A , MSP430F6775 , MSP430F67751 , MSP430F67751A , MSP430F6775A , MSP430F6776 , MSP430F67761 , MSP430F67761A , MSP430F6776A , MSP430F6777 , MSP430F67771 , MSP430F67771A , MSP430F6777A , MSP430F6778 , MSP430F67781 , MSP430F67781A , MSP430F6778A , MSP430F6779 , MSP430F67791 , MSP430F67791A , MSP430F6779A , MSP430FR2000 , MSP430FR2032 , MSP430FR2033 , MSP430FR2100 , MSP430FR2110 , MSP430FR2111 , MSP430FR2153 , MSP430FR2155 , MSP430FR2310 , MSP430FR2311 , MSP430FR2353 , MSP430FR2355 , MSP430FR2422 , MSP430FR2433 , MSP430FR2475 , MSP430FR2476 , MSP430FR2512 , MSP430FR2522 , MSP430FR2532 , MSP430FR2533 , MSP430FR2632 , MSP430FR2633 , MSP430FR2672 , MSP430FR2673 , MSP430FR2675 , MSP430FR2676 , MSP430FR4131 , MSP430FR4132 , MSP430FR4133 , MSP430FR5041 , MSP430FR5043 , MSP430FR50431 , MSP430FR5720 , MSP430FR5721 , MSP430FR5722 , MSP430FR5723 , MSP430FR5724 , MSP430FR5725 , MSP430FR5726 , MSP430FR5727 , MSP430FR5728 , MSP430FR5729 , MSP430FR5730 , MSP430FR5731 , MSP430FR5732 , MSP430FR5733 , MSP430FR5734 , MSP430FR5735 , MSP430FR5736 , MSP430FR5737 , MSP430FR5738 , MSP430FR5739 , MSP430FR5739-EP , MSP430FR5847 , MSP430FR58471 , MSP430FR5848 , MSP430FR5849 , MSP430FR5857 , MSP430FR5858 , MSP430FR5859 , MSP430FR5867 , MSP430FR58671 , MSP430FR5868 , MSP430FR5869 , MSP430FR5870 , MSP430FR5872 , MSP430FR58721 , MSP430FR5887 , MSP430FR5888 , MSP430FR5889 , MSP430FR58891 , MSP430FR5922 , MSP430FR59221 , MSP430FR5947 , MSP430FR59471 , MSP430FR5948 , MSP430FR5949 , MSP430FR5957 , MSP430FR5958 , MSP430FR5959 , MSP430FR5962 , MSP430FR5964 , MSP430FR5967 , MSP430FR5968 , MSP430FR5969 , MSP430FR5969-SP , MSP430FR59691 , MSP430FR5970 , MSP430FR5972 , MSP430FR59721 , MSP430FR5986 , MSP430FR5987 , MSP430FR5988 , MSP430FR5989 , MSP430FR5989-EP , MSP430FR59891 , MSP430FR5992 , MSP430FR5994 , MSP430FR59941 , MSP430FR6005 , MSP430FR6007 , MSP430FR6035 , MSP430FR6037 , MSP430FR60371 , MSP430FR6041 , MSP430FR6043 , MSP430FR60431 , MSP430FR6045 , MSP430FR6047 , MSP430FR60471 , MSP430FR6820 , MSP430FR6822 , MSP430FR68221 , MSP430FR6870 , MSP430FR6872 , MSP430FR68721 , MSP430FR6877 , MSP430FR6879 , MSP430FR68791 , MSP430FR6887 , MSP430FR6888 , MSP430FR6889 , MSP430FR68891 , MSP430FR6920 , MSP430FR6922 , MSP430FR69221 , MSP430FR6927 , MSP430FR69271 , MSP430FR6928 , MSP430FR6970 , MSP430FR6972 , MSP430FR69721 , MSP430FR6977 , MSP430FR6979 , MSP430FR69791 , MSP430FR6987 , MSP430FR6988 , MSP430FR6989 , MSP430FR69891

 

  1.   Trademarks
  2. 1Introduction to ESD
    1. 1.1 Component-Level ESD Rating
      1. 1.1.1 Human Body Model (HBM)
      2. 1.1.2 Charged Device Model (CDM)
    2. 1.2 System-Level ESD Rating
    3. 1.3 ESD Waveforms
  3. 2General System-Level ESD Design Guidelines
    1. 2.1 Enclosures
      1. 2.1.1 Enclosure Openings
      2. 2.1.2 Enclosure Cables
    2. 2.2 PCB Design and Layout
      1. 2.2.1 Example Layout – Current Loop
    3. 2.3 On-Board ESD Protection Devices
      1. 2.3.1 Simple Passive Components
      2. 2.3.2 ESD Suppression Devices
      3. 2.3.3 ESD Protection Using Series Resistor
    4. 2.4 Circuit Design and Software Considerations
      1. 2.4.1 Circuit Design
      2. 2.4.2 Software Considerations
    5. 2.5 ESD Testing
  4. 3System Efficient ESD Design (SEED)
    1. 3.1 System-Level ESD Protection Methodology
      1. 3.1.1 On-Board Protection – Primary Clamp
      2. 3.1.2 On-Chip Protection – Secondary Clamp
      3. 3.1.3 Two-Stage Protection – Fundamental SEED Concept
    2. 3.2 SPICE Simulation Methodology for System-Level ESD Design
  5. 4SEED-Based IEC Protection Design and Verification – Real World Example 1
    1. 4.1 Modeling IEC Stress Waveform
    2. 4.2 Modeling TVS Device
    3. 4.3 Modeling MSP430 I/O Pin
    4. 4.4 Isolated Impedance Calculation
    5. 4.5 SPICE Simulation – SEED Method
    6. 4.6 Board-Level Verification
  6. 5System-Level ESD Protection – Real World Example 2
  7. 6Summary
  8. 7Modeling Using TLP Parameters
    1. 7.1 Modeling TVS Device Using TLP Parameters [8]
    2. 7.2 Modeling IC Interface Pin to be Protected Using TLP Parameters [8]
  9. 8References
  10.   Revision History

4.4 Isolated Impedance Calculation

Figure 4-3 shows the SEED method simulation of the IEC protection using SEED parameters to model the TVS device and the MSP430 I/O pin as discussed in previous sections.

GUID-74303008-1A47-4C44-80DF-F6867505DA51-low.png Figure 4-3 SEED Method Simulation Schematic

Figure 4-3 shows that the IEC ESD current pulse is first bypassed to GND by the TVS device (primary clamp) and the decoupling capacitor; thus, limiting the induced voltage of the IEC stress pulse. The TVS max diode breakdown voltage plus the dynamic voltage across the TVS (based on the on-resistance and current through the TVS) represents the voltage of the residual pulse that is presented at the isolation impedance. Using a decoupling capacitor in parallel to the TVS model limits the voltage due to the initial fast transient current peak of the IEC pulse at the TVS node. Therefore, for all further calculations, the peak IEC current of the slow discharge curve (which is approximately 18 A) is used. With max IEC pulse current (IIEC,max) approximately 18 A and TVS on-resistance (RTVS,on,max) approximately 1 Ω, the maximum voltage of the residual pulse presented at the isolated impedance is calculated as:

VTVS,max = VTVS,t1,max + (IIEC,max × RTVS,on,max)

VTVS,max = 9.5 V + (18 A × 1 Ω)

VTVS,max ≈ 27.5 V

In this case, the isolation impedance is represented by a resistor between the primary and secondary clamps. The value of this resistor is calculated based on the max voltage drop across the resistor required such that the worst-case ESD current and voltage presented at the IC pin is not violated by the residual ESD stress

Given the MSP430 I/O pin on-chip ESD protection turn-on voltage (when ESD protection is triggered) of VIC,t1,min = 2.6 V, minimum on-resistance value of RIC,on,min = 1.15 Ω, and the maximum acceptable current of IIC,max = 1.47 A, the maximum acceptable voltage that can be presented to the IC pin is calculated as:

VIC,max = VIC,t1,min + (IIC,max × RIC,on,min)

VIC,max = 2.6 V + (1.47 A × 1.15 Ω)

VIC,max ≈ 4.3 V

As a result, the minimum isolation or decoupling resistance value is calculated as:

GUID-77B8CB04-A0D8-4427-851B-23096469D95B-low.gif