VCS1610 (Kelvin Connection) Vishay Foil Resistors High Precision Foil Surface Mount Current Sensing Chip Resistors with TCR of 2 ppm/C, Load Life Stability of 0.02 %, ESD Immunity up to 25 kV and Fast Thermal Stabilization FEATURES Temperature coefficient of resistance (TCR): 2.0 ppm/C typical (- 55 C to + 125 C, + 25 C ref.) (see table 1) Tolerance: to 0.5 % Load life stability: 0.02 % at 70 C, 2000 h at rated power Power rating: 0.25 W at + 70 C TERMINATIONS Resistance range: 0.1 to 1 (for higher or lower values please contact Vishay application engineering Two lead (Pb)-free options are available: department) Gold plated or tin plated Vishay Foil resistors are not restricted to standard values Tin/lead plated specific as required values can be supplied at no extra cost or delivery (e.g. 0.2345 vs. 0.2 ) Electrostatic discharge (ESD) up to 25 000 V TABLE 1 - TOLERANCE AND TCR VS. Thermal stabilization time < 1 s RESISTANCE VALUE Short time overload 0.005 % (- 55 C to + 125 C, + 25 Ref.) Non-inductive, non-capacitive design VALUE TYPICAL MAXIMUM Thermal EMF: 0.05 V/C typical TOLERANCE () TCR TCR Current noise: < - 42 dB 0R5 to 1R 0.5 %, 1 % 2 ppm/C 10 ppm/C Rise time: 1 ns effectively no ringing Voltage coefficient: < 0.1 ppm/V 0R1 to 0R5 0.5 %, 1 % 2 ppm/C 15 ppm/C Non inductive: < 0.08 H Weight: 0.027 mg Note Compliant to RoHS directive 2002/95/EC Tighter tolerances and higher values are available. Please Prototype quantities available in just 5 working days contact application engineering foil vishaypg.com or sooner. For more information, please contact foil vishaypg.com For improved performances, please see VCS1610Z INTRODUCTION Why should I use the VCS1610 The VCS1610 is used where the emphasis is on accuracy and repeatability under stress conditions in applications The VCS1610 is a current sensing solution that was requiring precision resistor performance up to 0.25 W and up developed with a low TCR to meet demands for new and to 70 C. Applications as EB systems, switching power stable resistive product solutions in the industry today. This supplies, force-balanced scales all rely on current sense resistor is most-often used to monitor a current that is directly resistors to develop a precise voltage proportional to the proportional to some physical characteristic (such as current. The VCS1610 is a four terminal resistor which is pressure, weight, etc) being measured by an analog sensor. essential to achieve high accuracy and stability. The resistor converts the current to a voltage that is representative of the physical characteristic and feeds that Why use Kelvin connections voltage into control circuits, instrumentation, or other Four-terminal connections or Kelvin connections are indicators. required in these low ohmic value resistors to measure a Variations induced in the resistor, not representative of the precise voltage drop across the resistive element. The monitored characteristic, can be caused by high TCR 4-terminal configuration eliminates the IR-drop error voltage response to both ambient temperature and self-heating and that would be present in the voltage sense leads if a standard can feed erroneous signals into the system. Resistance is two-terminal resistor were used. usually kept low to reduce the IR self-heating (Joule effect) In current sense resistors the contact resistance and the portion of the error while minimizing the stresses that cause terminations resistance may be greater than that of the long-term resistance changes. It is critical for this resistor to resistive element itself so lead connection errors can be reach thermal equilibrium quickly in circuits that require fast significant if only two terminal connections are used. response or where the current changes quickly. * Pb containing terminations are not RoHS compliant, exemptions may apply Document Number: 63137 For any questions, contact: foil vishaypg.com www.foilresistors.com Revision: 25-Mar-10 1VCS1610 (Kelvin Connection) Vishay Foil Resistors Why is the VCS1610 vital to avoid Thermal EMF Should I be concerned about stability (parasitic effect) In order to select the resistor technology most appropriate to the application, a designer must take into account all normal When the junction of two dissimilar metals is heated, a and extraordinary stresses the resistor will experience in the voltage is generated across the junction creating a DC-offset application. In addition, the designer must consider the cost error signal. This voltage is proportional to the temperature and reliability impact involved when it becomes necessary to difference across the junction and is called a Thermal add costly additional compensating circuitry when Electro-motive Force (Thermal EMF), or thermocouple. inadequate resistors are selected. The stability of Bulk Metal Thermal EMF is an important consideration in low ohmic Foil resistors, together with the advantages already current sensing resistors used mostly in DC circuits (there is mentioned, as well as the other basic advantages apparent no effect in AC circuitry). The VCS1610 is the ideal solution in their specifications will not only provide unequalled to minimize the effect of thermal EMF through the use of performance in the circuit but will eliminate all the costs appropriate materials between the resistive layer and the associated with extra compensation circuitry. terminations. With VCS1610, only a minimal shift in resistance value will Should I be concerned about ESD impact on my occur during its entire lifetime. Most of this shift takes place resistor during the first few hundred hours of operation, and virtually Electrostatic Discharge (ESD) is known to produce no change is noted thereafter. catastrophic failures in thin-film and thick-film (cermet) resistors at only 3000 V. On the other hand, the Bulk Metal Foil resistor withstands ESD events up to 25 000 V because its thicker resistance element and greater metallic mass afford much higher energy-handling capability than either the much thinner thin-film resistor or the sparse, non-homogeneous metallic content of the thick film resistor. (1) FIGURE 1 - POWER DERATING CURVE - 55 C + 70 C 100 75 50 25 0 - 75 - 50 - 25 0 + 25 + 50 + 75 + 100 + 125 + 150 + 175 Ambient Temperature (C) Note (1) Power rating: 0.25 W at + 70 C FIGURE 2 - DIMENSIONS in inches (millimeters) 0.060 Mounting L A 0.020 (1.524) Pads (4) I E (0.508) 1 2 I E 2 1 B R H W 0.200 E I E I 2 1 1 2 (5.08) Top View Bottom View Solder Pad Layout Electrical Schematic INCHES MILLIMETERS L 0.160 0.010 4.06 0.25 H 0.100 0.010 2.54 0.25 W 0.040 maximum 1.02 maximum A 0.045 0.005 1.14 0.13 B 0.030 0.010 0.76 0.25 www.foilresistors.com For any questions, contact: foil vishaypg.com Document Number: 63137 2 Revision: 25-Mar-10 Percent of Rated Power 0.110 (2.794)