SPRA953D December   2003  – March 2024 CSD13201W10 , CSD13202Q2 , CSD13302W , CSD13303W1015 , CSD13306W , CSD13380F3 , CSD13381F4 , CSD13383F4 , CSD13385F5 , CSD15380F3 , CSD15571Q2 , CSD16301Q2 , CSD16321Q5 , CSD16322Q5 , CSD16323Q3 , CSD16325Q5 , CSD16327Q3 , CSD16340Q3 , CSD16342Q5A , CSD16401Q5 , CSD16403Q5A , CSD16404Q5A , CSD16406Q3 , CSD16407Q5 , CSD16408Q5 , CSD16409Q3 , CSD16410Q5A , CSD16411Q3 , CSD16412Q5A , CSD16413Q5A , CSD16414Q5 , CSD16415Q5 , CSD16556Q5B , CSD16570Q5B , CSD17301Q5A , CSD17302Q5A , CSD17303Q5 , CSD17304Q3 , CSD17305Q5A , CSD17306Q5A , CSD17307Q5A , CSD17308Q3 , CSD17309Q3 , CSD17310Q5A , CSD17311Q5 , CSD17312Q5 , CSD17313Q2 , CSD17318Q2 , CSD17322Q5A , CSD17327Q5A , CSD17381F4 , CSD17382F4 , CSD17483F4 , CSD17484F4 , CSD17501Q5A , CSD17505Q5A , CSD17506Q5A , CSD17507Q5A , CSD17510Q5A , CSD17522Q5A , CSD17527Q5A , CSD17551Q3A , CSD17551Q5A , CSD17552Q3A , CSD17552Q5A , CSD17553Q5A , CSD17555Q5A , CSD17556Q5B , CSD17559Q5 , CSD17570Q5B , CSD17571Q2 , CSD17573Q5B , CSD17575Q3 , CSD17576Q5B , CSD17577Q3A , CSD17577Q5A , CSD17578Q3A , CSD17578Q5A , CSD17579Q3A , CSD17579Q5A , CSD17581Q3A , CSD17581Q5A , CSD17585F5 , CSD18501Q5A , CSD18502KCS , CSD18502Q5B , CSD18503KCS , CSD18503Q5A , CSD18504KCS , CSD18504Q5A , CSD18509Q5B , CSD18510KCS , CSD18510KTT , CSD18510Q5B , CSD18511KCS , CSD18511KTT , CSD18511Q5A , CSD18512Q5B , CSD18513Q5A , CSD18514Q5A , CSD18531Q5A , CSD18532KCS , CSD18532NQ5B , CSD18532Q5B , CSD18533KCS , CSD18533Q5A , CSD18534KCS , CSD18534Q5A , CSD18535KCS , CSD18535KTT , CSD18536KCS , CSD18536KTT , CSD18537NKCS , CSD18537NQ5A , CSD18540Q5B , CSD18541F5 , CSD18542KCS , CSD18542KTT , CSD18543Q3A , CSD18563Q5A , CSD19501KCS , CSD19502Q5B , CSD19503KCS , CSD19505KCS , CSD19505KTT , CSD19506KCS , CSD19506KTT , CSD19531KCS , CSD19531Q5A , CSD19532KTT , CSD19532Q5B , CSD19533KCS , CSD19533Q5A , CSD19534KCS , CSD19534Q5A , CSD19535KCS , CSD19535KTT , CSD19536KCS , CSD19536KTT , CSD19537Q3 , CSD19538Q2 , CSD19538Q3A , CSD22202W15 , CSD22204W , CSD22205L , CSD22206W , CSD23202W10 , CSD23203W , CSD23280F3 , CSD23285F5 , CSD23381F4 , CSD23382F4 , CSD25202W15 , CSD25211W1015 , CSD25213W10 , CSD25304W1015 , CSD25310Q2 , CSD25402Q3A , CSD25404Q3 , CSD25480F3 , CSD25481F4 , CSD25483F4 , CSD25484F4 , CSD25485F5 , CSD25501F3 , CSD75207W15 , CSD75208W1015 , CSD83325L , CSD85301Q2 , CSD85302L , CSD85312Q3E , CSD86311W1723 , CSD86330Q3D , CSD86336Q3D , CSD86350Q5D , CSD86356Q5D , CSD86360Q5D , CSD87312Q3E , CSD87313DMS , CSD87330Q3D , CSD87331Q3D , CSD87333Q3D , CSD87334Q3D , CSD87335Q3D , CSD87350Q5D , CSD87351Q5D , CSD87351ZQ5D , CSD87352Q5D , CSD87353Q5D , CSD87355Q5D , CSD87381P , CSD87384M , CSD87501L , CSD87502Q2 , CSD87503Q3E , CSD87588N , CSD88537ND , CSD88539ND , CSD88584Q5DC , CSD88599Q5DC , DS90UH940N-Q1 , LM22670 , LM22671 , LM22671-Q1 , LM22672 , LM22672-Q1 , LM22673 , LM22673-Q1 , LM22674 , LM22674-Q1 , LM22675 , LM22675-Q1 , LM22676 , LM22676-Q1 , LM22677 , LM22677-Q1 , LM22678 , LM22678-Q1 , LM22679 , LM22679-Q1 , LM22680 , LM22680-Q1 , LM25574 , LM25574-Q1 , LM25575 , LM25575-Q1 , LM25576 , LM25576-Q1 , LM2574 , LM2574HV , LM2575 , LM2575HV , LM2576 , LM2576HV , LM2577 , LM2585 , LM2586 , LM2587 , LM2588 , LM2590HV , LM2591HV , LM2592HV , LM2593HV , LM2594 , LM2594HV , LM2595 , LM2596 , LM2597 , LM2597HV , LM2598 , LM2599 , LM2670 , LM2671 , LM2672 , LM2673 , LM2674 , LM2675 , LM2676 , LM2677 , LM2678 , LM2679 , LM2698 , LM2736 , LM2840 , LM2840-Q1 , LM2841 , LM2841-Q1 , LM2842 , LM2842-Q1 , LM3100 , LM3102 , LM3102-Q1 , LM3103 , LM3691 , LM43600 , LM43601 , LM43602 , LM43603 , LM46000 , LM46001 , LM46002 , LM5574 , LM5574-Q1 , LM5575 , LM5575-Q1 , LM5576 , LM5576-Q1 , LMR10510 , LMR10515 , LMR10520 , LMR10530 , LMR12007 , LMR12010 , LMR12015 , LMR12020 , LMR14203 , LMR14206 , LMR16006 , LMR24210 , LMR24220 , LMR61428 , LMR62014 , LMR62421 , LMR64010 , LMR70503 , SN74SSQE32882 , SN74SSQEA32882 , TMS320C28341 , TMS320C28342 , TMS320C28343 , TMS320C28343-Q1 , TMS320C28344 , TMS320C28345 , TMS320C28346 , TMS320C28346-Q1 , TMS320F280021 , TMS320F280021-Q1 , TMS320F280023 , TMS320F280023-Q1 , TMS320F280023C , TMS320F280025 , TMS320F280025-Q1 , TMS320F280025C , TMS320F280025C-Q1 , TMS320F280040-Q1 , TMS320F280040C-Q1 , TMS320F280041 , TMS320F280041-Q1 , TMS320F280041C , TMS320F280041C-Q1 , TMS320F280045 , TMS320F280048-Q1 , TMS320F280048C-Q1 , TMS320F280049 , TMS320F280049-Q1 , TMS320F280049C , TMS320F280049C-Q1 , TMS320F2801 , TMS320F2801-Q1 , TMS320F2802-Q1 , TMS320F28020 , TMS320F28021 , TMS320F28022 , TMS320F28022-Q1 , TMS320F28023 , TMS320F28023-Q1 , TMS320F28026 , TMS320F28026-Q1 , TMS320F28026F , TMS320F28027 , TMS320F28027-Q1 , TMS320F28027F , TMS320F28027F-Q1 , TMS320F28030 , TMS320F28030-Q1 , TMS320F28031 , TMS320F28031-Q1 , TMS320F28032 , TMS320F28032-Q1 , TMS320F28033 , TMS320F28033-Q1 , TMS320F28034 , TMS320F28034-Q1 , TMS320F28035 , TMS320F28035-Q1 , TMS320F28050 , TMS320F28051 , TMS320F28052 , TMS320F28052-Q1 , TMS320F28052F , TMS320F28052F-Q1 , TMS320F28052M , TMS320F28052M-Q1 , TMS320F28053 , TMS320F28054 , TMS320F28054-Q1 , TMS320F28054F , TMS320F28054F-Q1 , TMS320F28054M , TMS320F28054M-Q1 , TMS320F28055 , TMS320F2806 , TMS320F2806-Q1 , TMS320F28062 , TMS320F28062-Q1 , TMS320F28062F , TMS320F28062F-Q1 , TMS320F28063 , TMS320F28064 , TMS320F28065 , TMS320F28066 , TMS320F28066-Q1 , TMS320F28067 , TMS320F28067-Q1 , TMS320F28068F , TMS320F28068M , TMS320F28069 , TMS320F28069-Q1 , TMS320F28069F , TMS320F28069F-Q1 , TMS320F28069M , TMS320F28069M-Q1 , TMS320F28075 , TMS320F28075-Q1 , TMS320F2808 , TMS320F2808-Q1 , TMS320F2810 , TMS320F2810-Q1 , TMS320F2811 , TMS320F2811-Q1 , TMS320F2812 , TMS320F2812-Q1 , TMS320F28232 , TMS320F28232-Q1 , TMS320F28234 , TMS320F28234-Q1 , TMS320F28235 , TMS320F28235-Q1 , TMS320F28332 , TMS320F28333 , TMS320F28334 , TMS320F28335 , TMS320F28335-Q1 , TMS320F28374D , TMS320F28374S , TMS320F28375D , TMS320F28375S , TMS320F28375S-Q1 , TMS320F28376D , TMS320F28376S , TMS320F28377D , TMS320F28377D-Q1 , TMS320F28377S , TMS320F28377S-Q1 , TMS320F28379D , TMS320F28379D-Q1 , TMS320F28379S , TMS320LF2401A , TMS320LF2402A , TMS320LF2403A , TMS320LF2406A , TMS320LF2407A , TPS54020 , TPS54218 , TPS54318 , TPS54320 , TPS54418 , TPS54478 , TPS54618 , TPS54622 , TPS54623 , TPS54678 , TPS56121 , TPS56221

 

  1.   1
  2.   Semiconductor and IC Package Thermal Metrics
  3.   Trademarks
  4. 1RθJA Junction-to-Ambient and RθJMA Junction-to-Moving Air
    1. 1.1 Usage
    2. 1.2 Test Card Impact
    3. 1.3 Die Size Impact
    4. 1.4 Internal Package Geometrical Configuration
    5. 1.5 Altitude
    6. 1.6 Ambient Temperature
    7. 1.7 Power Dissipation
    8. 1.8 RθJA Effective
  5. 2RθJC Junction-to-Case
    1. 2.1 Copper (Cu) Cold Plate RθJC Measurement
    2. 2.2 RθJC Application
    3. 2.3 Rθ(CS)
    4. 2.4 RθJC(top) and RθJC(bot)
  6. 3ΨJT, Junction to Top of Package
    1. 3.1 Case Temperature Measurement
    2. 3.2 ΨJT vs RθJC When Using Heat Sinks
  7. 4Rθ(JB) Junction-To-Board
    1. 4.1 Rθ(JB) Measurement Method
  8. 5ΨJB Junction-to-Board Characterization Parameter
    1. 5.1 ΨJB Application
  9. 6Industrial and Commercial Temperature Ranges
  10. 7Miscellaneous Definitions
  11. 8References
  12. 9Revision History

4 Rθ(JB) Junction-To-Board

The junction-to-board thermal resistance, or junction-to-pin thermal resistance, attempts to represent the thermal resistance between the package and the board with one number. In reality, the resistance between the junction and board is distributed, with different resistance paths such as the junction-to-pin-to-board and the junction-through-plastic-through-air-to-board. Furthermore, the concept of RθJB implies that the board temperature under the device is uniform temperature (single node), which is erroneous. Nevertheless, a single thermal metric like Rθ(JB) is useful for a first-pass estimation of junction temperature based on the following simple three-resistor thermal approximation as shown in Figure 4-1. In this model, the resistance from the junction-to-board is simply the Rθ(JB) value. The resistance between the junction and case surface is simply the RθJC value. The ambient resistance, Rθ(a), is calculated from the convective heat loss and radiation loss from the top of the package.

GUID-AF46D39F-066B-4C31-86EB-F80423AA1481-low.gif Figure 4-1 Three-Resistor Thermal Approximation Model