CSS CSSH Ultra Precision Current Sensing Chip Resistor SEI Resistance by MikeJenny


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									  CSS / CSSH Ultra Precision
Current Sensing Chip Resistor
             Training Module
            Provide a basic overview of Stackpole’s CSS and CSSH series of
            current sense resistor chips
            Explain the important parameters for engineers choosing a current
            sense resistor
            Discuss the advantages that the CSS / CSSH specifically provides for
            those parameters
            Examine applications, end products, and future trends for this product
            10 pages
 Learning Time
            10 minutes
Welcome to the Stackpole CSS and CSSH Ultra Precision Current Sense Chip Resistor Training Module.
This module will explain how the CSS and CSSH series of resistors is truly one of the most accurate and
                              stable current sense resistors in the industry.
                                            CSS/CSSH Materials, Design
                                                     and Construction
          The CSS/CSSH series uses a specially formulated resistive alloy to achieve very
          low TCR’s

          As compared to other metal element current sense resistors, the CSS/CSSH
          terminations are mechanically crimped onto the resistive alloy for higher
          temperature operation

          Precise resistance values are achieved through a proprietary trimming process,
          providing for resistance tolerances down to 0.5%

                           Metal Alloy         Marking           Protective Layer

                                                                         External Electrode (Sn Plated)
                                                                         Secondary Electrode (Ni Plated)
                                                                         Internal Electrode (Cu Plated)

 The CSS and CSSH series uses specialized materials designed to achieve extremely low resistance values with high
precision. The unique termination process allows for much higher temperature operation compared to other termination
                   methods. The proprietary trimming process allows for tolerances down to 0.5%.
                                                            Important Factors for
                                                                Current Sensing
                           Stackpole’s CSS / CSSH
                          outperforms the competition
           Low Resistance Values

           High Power Rating

           Improved Power Handling For Given Chip Sizes

           Electrical Stability – Low TCR, Tight Resistance Tolerance

           High Temperature Operation

    With the proliferation of portable electronics, the design engineer is challenged with reducing size,
improving power handling, and improving electrical performance. The CSS and CSSH series is specifically
                                   designed with these challenges in mind.
                                           Low Resistance Values for
                                        High Efficiency Requirements
                                                                                                Power vs. Current

          The lower the resistance value,                                     35
          the less power is used for the
          current sensing operation.                                          30

          Stackpole offers resistance values                                  25

          down to 0.25 milliohms – among

                                                             Power in Watts
                                                                                                                          0.005 ohms
          the lowest currently available in                                                                               0.001 ohms

          the market.                                                         15
                                                                                                                          0.00025 ohms

          These low resistance values allow
          for the highest current handling                                    5

                                                                                   10   20          40          60   80
                                                                                             Current in Am ps

   When efficiency is most important, lower resistance values for the current sense resistor is critical.
The .25 milliohm value offered by this series allows for sensing high amounts of current while keeping the
                                  power dissipation as low as possible.
                                                         High Power Ratings

      As electronic content and functions increase, increasing amounts of
      current are required to power these features.

      As shown on the previous slide, higher current levels require higher power

      In the past, 3 and 4 watt SMD current sense solutions were hard to find,
      large and bulky, expensive, limited in resistance values offered, and had
      poor TCR or resistance tolerance.

      The cost effective CSS 2725 and CSSH 2728 offer 4 watts of power
      handling with TCR down to 15 ppm and tolerances as low as 0.5% in
      resistance values from 0.25 milliohm up to 50 milliohm.

The CSS / CSSH series offers a significant improvement in stability, precision, and power handling
              compared to other surface mountable solutions available today.
                                                     High Power Ratings for
                                                     a Given Package Sizes

        Downsizing electronic products whether to make it smaller or to add
        features usually means sacrificing power handling or performance,
        limiting resistance values offered, or increasing sense resistor cost.

        Current sensing resistors in general have higher power ratings than their
        standard chip resistor equivalents.

        Stackpole’s CSSH2512 offers a unique 3 watt power rating in a package
        size usually limited to 2 watts.

Higher power ratings for 2512 size resistors and smaller allows the design engineer to utilize the space
        normally needed for power management for other functions to the product or to make
                                        the end product smaller.
                                                   High Precision Capability
                                                       Competitive Analysis

                      Ω Values            Tolerance                TCR                  Comments

CSS / CSSH      .00025 to 0.1 ohm 0.5%, 1%, 5%              15ppm, 25 ppm,
                                                                50 ppm
                                                                                      Better precision
Comp. A         .001 to 0.5 ohm         0.5%, 1%, 5%         75 ppm typical         requires a different
Comp. B         0.001 to 0.02 ohm           1%, 5%         75 ppm, 150 ppm,            No 3 or 4 watt
                                                               200 ppm                 option offered
                                                                                     No 4 watt option
Comp. C         0.002 to 1.0 ohm         1%, 2%, 5%         100 ppm at best              offered

  Other competitive products require different series for lower resistance values, another for
     lower TCR’s, another for tighter tolerances, or for power ratings higher than 2 watts.

          No other product currently available offers the same combination of low resistance values,
                           excellent resistance tolerance, and extreme low TCR’s.
                                     High Temperature Operation

       The high current / high power
       environment that current sense
       resistors live in requires stability
       at high temperatures

       The CSS / CSSH offers
       operation at full rated power up
       to 100C.

       It also offers operation up to
       275C, which is usually only
       offered in special series from
       competitors and in limited sizes
       and resistance values.

The CSS / CSSH series offers full power operation to higher temperatures and offers power derated
           operation to higher temperatures than any other product currently available.
                                                     Future Developments

       ¼ watt and ½ watt 0805 size chip

       1 watt 1206 size chip

       2 watt 2010 size chip

       5 watt chip

       Lower resistance values for all sizes

       Improved TCR for a wider resistance range

The CSS and CSSH series and the benefits of the unique materials and manufacturing processes will
   lend themselves to keeping pace with the requirements of the current sensing resistor market.

        Low Resistance Values – available down to 0.25 milliohms at 50 ppm

        High Power Handling – 3 watt 2512 size chip, 4 watt 2725 and 2728
        size chips

        High Precision / Electrical Stability - 0.5% resistance tolerance and 50
        ppm TCR available for the entire resistance range.

        Robust High Temperature Operation – full rated power handling up to
        100C and power derated operation up to 275C.

The CSS / CSSH series offers unmatched precision, power handling, and resistance values in a single
  series, making it easy to use this single series a great choice for all current sensing requirements.

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