Low value current-sensing resistors reduce design footprint

Latest from TT Electronics is the LCS series of thin-film resistors for sensing and measurement of DC and AC currents in the sub-3A range. The resistors bring precision thin-film resistor performance into the field of low ohmic values for use in highly-accurate current-sensing applications. Most thin film chips have a minimum value in the range of one to 10ohm. The TT Electronics’ LCS series uses a proprietary technology to extend this down to 100mohm. The resistors also feature low sensitivity to temperature variations. Aimed at designers of power supplies, battery monitoring, process control and point-of-load (PoL) converters, the LCS resistors will find acceptance for use in market sectors such as industrial, medical, instrumentation and IT. The resistors offer a level of precision of ±0.5% and ±50ppm/C, providing higher precision and temperature stability of current measurement. While there are currently a few thin-film chip products below one ohm that use the nickel phosphorus material traditionally used for low value films, TT's proprietary LCS film system delivers lower TCRs (temperature coefficient of resistance) in the hundreds of milliohms range. Available in five sizes from 0603 to 2512, LCS resistors feature high power ratings, e.g. 1W for 2512, which is comparable to thick film ratings. This also enables smaller footprints to be used. Enhancing reliability and reducing field failures in industrial applications, LCS also feature anti-sulphur terminations. A major factor driving the demand for this type of product is the growth of battery-powered equipment. The proprietary thin-film technology bridges the gap between the ohmic values offered by bulk metal chips and those of conventional nichrome thin film chips. While thick-film chips are also available in this very low ohmic range, LCS offers superior precision, offering the lowest TCR for precision current sensing available in the 0.1ohm to 1ohm range, says the company.