Open Air Current Sense Resistors OAR Series * * * * * TCR's to 20ppm/C Power ratings of 1, 3, & 5W @ 85C Resistance range from 2.5m to 100m Open air design maximizes thermal performance Welded copper leads minimize effects from solder wicking and provide true 1% performance Features: * Welded construction * Flameproof * Inductance less than 10 nanohenries * Solderable copper leads (60/40) and Lead-Free Applications: * Current sensing * Feedback * Motor Controllers * Power Supplies Electrical Data Part Number Power Rating @ 85C (watts) Resistance Range (m) OAR-1 1.0 3, 5, 10, *20, *25, 50 OAR-3 3.0 2.5, 5, 10, 15, 20, 25, *30, 50, 100 OAR-5 5.0 3, 5, 10, *15, *20, *25, *50 Tolerance (%) TCR (ppm/C) Inductance (nH) 1, 2, 5 20 <10 Notes: 2% tolerance available <0.005m * denotes resistance values that may have longer lead times than other values listed * Please contact factory for resistance values not listed Environmental Data Load Life (1000 hours @ 25C) R/R <1% Moisture (no load for 1000 hours) R/R <1% Temperature Cycling (-40C to +125C for 1000 cycles) R/R <1% Operating Temperature -40C to +125C General Note IRC reserves the right to make changes in product specification without notice or liability. All information is subject to IRC's own data and is considered accurate at time of going to print. Wire and Film Technologies Division * 4222 South Staples Street * Corpus Christi Texas 78411 USA Telephone: 361 992 7900 * Facsimile: 361 992 3377 * Website: www.irctt.com A subsidiary of TT electronics plc OAR Series Issue January 2010 Sheet 1 of 3 Open Air Current Sense Resistors Physical Data On lower ranges stand-off may be eliminated 2ESISTIVE %LEMENT #OPPER ,EADS NOTE: Contact factory for: 1. Variations of "A" dimension. 2. Different lead diameter. B 7ELD .ODE C 3TAND /FF E F Test Point (Kelvin connection) A Dimensions (Inches and (mm)) IRC Type OAR-1 OAR-3 OAR-5 A B C E F 0.450 +0.040/-0.020 0.200 0.100 0.125 0.030 0.065 +0.010/-0.005 0.040 0.002 (11.43 +1.020/-0.508) (5.08 2.54) (3.18 0.762) (1.65 +0.254/-0.127) (1.02 0.051) 0.600 +0.040/-0.020 0.600 Typ 0.125 0.030 0.065 +0.010/-0.005 0.040 0.002 (15.24 +1.020/0.508) (15.3 max.) (3.18 0.762) (1.65 +0.254/-0.127) (1.02 0.051) 0.800 +0.040/-0.020 0.670 Typ 0.125 0.030 0.065 +0.010/-0.005 0.040 0.002 (20.32 +1.020/-0.508) (8.9 max.) (3.18 0.762) (1.65 +0.254/-0.127) (1.02 0.051) Thermal Image Data OAR-1 5 m @ 1 Watt OAR-3 5 m @ 3 Watt OAR-5 5 m @ 5 Watt Hot Spot: 87C Solder Joint: 45C Hot Spot: 160C Solder Joint: 70C Hot Spot: 230C Solder Joint: 96C The thermal images (not simulations) above are of the OARs products at their respective power rating. Notice the solder joint temperature is much lower than the hotspot. The unique construction of the OAR isolates the temperature of the hotspot from the circuit board material preventing damage to the circuit board. Additionally, the thermal energy is dissipated to the air instead of being conducted into the circuit board potentially causing a nearby power component to exceed its rating. The standard test circuit board consists of a four layer FR4 material with 2 ounce outer layers and 1 ounce inner layers, which is typical of many industry designs. The test conditions were in ambient temperature conditions, approximately 72 C with no forced air. Contact IRC for more details or for other thermal image test data for specific resistance values and power levels. Wire and Film Technologies Division * 4222 South Staples Street * Corpus Christi Texas 78411 USA Telephone: 361 992 7900 * Facsimile: 361 992 3377 * Website: www.irctt.com OAR Series Issue January 2010 Sheet 2 of 3 Open Air Current Sense Resistors Power Derating The typical power derating curves are based on conservative design concepts that extend from film based products. The OAR is a solid metal alloy construction that can withstand comparably greater operating power levels than conservative design models permit. Typically the resistive alloys can withstand temperatures in excess of 300C. Therefore, system thermal design considerations are a more significant design parameter due to the heat limitations of solder joints and/or circuit board substrate materials. 1400 1400 600 1200 1200 500 400 300 200 100 Surge Current (Amps) 700 Surge Current (Amps) Surge Current (Amps) Pulse/Surge Chart @ 50 msec duration 1000 800 600 400 200 0 10 20 30 40 50 60 70 80 90 100 800 600 400 200 0 0 1000 0 0 10 20 Resistance (milli-ohms) 30 40 50 60 70 Resistance (milli-ohms) OAR-1 OAR-3 80 90 100 0 5 10 15 20 25 30 35 40 45 50 Resistance (milli-ohms) OAR-5 The Surge current charts are approximations of the capabilities of the OAR product and should not be used to the exclusion of actual testing. The relative high surge currents depicted in the charts are as a result of the robust all metal welded construction and the heat carrying capability of metal. Additionally the OAR resistive wire provides large relative cross section for current flow as compared to other resistor technologies, such as thin film, thick film, or metal strip. Ordering Data Sample Part No. OAR 1 R100 F LF IRC Style OAR Power Rating in Watts 1 = 1W, 3 = 3W, 5 = 5W Resistance Range `R' indicates decimal point location Tolerance F = 1%, G = 2%, J = 5% RoHS Indicator LF indicates RoHS compliance Blank indicates Sn/Pb terminal tinning; available on special request Wire and Film Technologies Division * 4222 South Staples Street * Corpus Christi Texas 78411 USA Telephone: 361 992 7900 * Facsimile: 361 992 3377 * Website: www.irctt.com OAR Series Issue January 2010 Sheet 3 of 3