VCS331Z, VCS332Z, VFP4Z, CSNGVCS331Z, VCS332Z, VFP4Z, CSNG Vishay Foil Resistors Bulk Metal Z-Foil Technology Ultra High-Precision 4-Terminal Power Current Sensing Resistors with TCR as Low as 0.05 ppm/C, Power up to 10 Watts and Thermal Stabilization of <1s FEATURES Low temperature coefficient of resistance (see figure 4): 0.05 ppm/C typical (0C to +60C) 0.2 ppm/C typical (55C to +125C, +25C ref.) VFP4Z Resistance range: 0R25 to 500R VCS331Z Resistance tolerance: to 0.01% VCS332Z Power rating: 10W on heatsink(1) at +25C 3W in free air at +25C (see Table 2) Load life stability: 0.005% (50 ppm) typical, 3W on heatsink at +25C, 2000h 0.01% (100 ppm) typical, 3W in free air at +25C, 2000h 0.01% typical (100 ppm), 10W on heatsink at CSNG +25C, 2000h Vishay Foil Resistors are not restricted to standard INTRODUCTION values specific as required values can be supplied at no extra cost or delivery (e.g. 1R2345 vs. 1R) The most precise measuring of electrical current is Rapid R stabilization under transient loads (see achieved by the current sensing resistor method. The Figure 2) precision and speed of response to changing current depend on thermal stability of the resistor, as determined Thermal resistance: 6C/W by its low temperature coefficient of resistance (TCR) and Electrostatic discharge (ESD) at least to 25 kV related power coefficient of resistance (PCR), as well as Rise time: 1 ns, effectively no ringing its net reactance. Tenfold improvement of power coefficient of VCS331Z, VCS332Z, and VFP4Z (0R25 to 500R) resistance (PCR): 4 ppm/W (see Figure 3) This series should be selected where rapid R Thermal stabilization time <1s (nominal value achieved stabilization and resistance stability under transient power within 10 ppm of steady state value) conditions is required. These products achieve optimum Voltage coefficient: <0.1 ppm/V performance when mounted on a chassis or cooled heat Current noise: 0.010 V /V of applied voltage RMS sink. The Z-Foil technology provides extremely low PCR (<40 dB) under defined conditions (see Figure 2 and Figure 3). The Inductance: 0.1 H maximum 0.08 H typical low absolute TCR provided by the Z-Foil technology is measured over the temperature range of 55C to +125C Thermal EMF: 0.1 V/C (see Table 3) or 0C to +60C, +25C reference (see Figure 4). Non-inductive, non-capacitive design All of these devices utilizing the Z-Foil technology are Pattern design minimizing hot spots provided with a true 4-terminal Kelvin connection. This is Note a must for precise current sensing when the resistance (1) Heatsinkaluminum (6 L x 4 W x 2 H x 0.04 THK) value is less than 100 (see Figure 6). CSNG New Generation of FIGURE 1TRIMMING TO VALUES Power Current Sense Resistors (>0R005) (conceptual illustration) Custom high power designs can be developed for your specific applications. Vishay Foil Resistors (VFR) recently Interloop Current Path introduced New Generation of Power Current Sense Capacitance Before Trimming Reduction Resistors (CSNG) with short thermal setting time, long- in Series Current Path term stability, high power to 20W and absolute TCR to Mutual After Trimming Inductance Reduction due 0.5 ppm/C maximum (see page 5). Trimming Process to Opposing Removes this Material Current in from Shorting Strip Area Adjacent Lines For more information, please contact Application Changing Current Path and Increasing Resistance Engineering Department at foil vishaypg.com. Note: Foil shown in black, etched spaces in white *Pb containing terminations are not RoHS compliant exemptions may appy Document No.: 63240Document No.: 63240 For questions, contact foil vishaypg.com www.vishayfoilresistors.com Revision: 13-Jun-2013Revision: 13-Jun-2013 18 VCS331Z, VCS332Z, VFP4Z, CSNG Vishay Foil Resistors FIGURE 2 RAPID STABILIZATION FIGURE 4 TYPICAL RESISTANCE/ TEMPERATURE CURVE (Z-FOIL) 15 + 500 10 + 400 + 300 5 + 200 0 + 100 R 0 R 5 (ppm) - 100 0.05 ppm/C 10 - 200 - 0.1 ppm/C 0.1 ppm/C - 300 15 0.14 ppm/C 020406080 100 120140 160180 200 - 400 - 0.16 ppm/C 0.2 ppm/C - 500 TIME, s - 55 - 25 0 + 25 + 60 + 75 + 100+ 125 RESISTANCE CHANGE UNDER LOAD AT 10 WATTS Ambient Temperature (C) MOUNTED ON COOLED HEAT SINK HELD AT + 25 C TCR Chord Slopes for Different Temperature Ranges FIGURE 3 POWER COEFFICIENT (PCR) FIGURE 5 POWER DERATING CURVE 60 40 - 55 C + 25 C 100 20 75 0 50 20 25 40 0 60 - 50 0 + 50 + 100 + 150 + 200 01 25 810 APPLIED POWER, W AMBIENT TEMPERATURE RESISTANCE CHANGE VS APPLIED POWER MOUNTED ON COOLED HEAT SINK HELD AT + 25 C FIGURE 6 KELVIN CONNECTION Kelvin, 4-terminal, connections are utilized for these low ohmic value products to measure a precise voltage drop across the resistive element. In these applications r R r 1 2 the contact resistance, lead resistance, and their TCR I I 1 2 E E effect may be greater than that of the element itself and 1 2 could cause significant errors if the standard 2-terminal r r 4 connection is used. Figure 6 shows a high impedance 3 I measurement system where r approaches infinity and I 5 m m 0 approaches zero resulting in negligible IR drop through r 3 and r which negates their lead resistance and their TCR 4 effect. With the voltage sense leads E and E inside of r 1 2 1 and r the resistance and TCR effect of the current leads, 2 r 5 I and I are negated and only the resistance and TCR of 1 2 the element R are sensed. This method of measurement is essential for precise current sensing. www.vishayfoilresistors.com For questions, contact foil vishaypg.com Document No.: 63240 2 Revision: 13-Jun-2013 RESISTANCE DEVIATION, ppm RESISTANCE DEVIATION, ppm RATED POWER (%)