• 4222 South Staples Street • Corpus Christi Texas 78411 USA

Wire and Film Technologies Division

Telephone: 361 992 7900 • Facsimile: 361 992 3377 • Website: www.irctt.com

Physical Data

Dimensions (Inches and (mm))

IRC

Type

L (Resistance

Dependant)

H (Resistance

Dependant)

TD

W

OARS-XP

0.425 - 0.470

(10.7 - 12.0)

0.090 - 0.180

(2.28 - 4.57)

0.093 ± 0.010

(2.36 ± 4.57)

0.190 ± 0.030

(4.83 ± 0.76)

0.250 ± 0.015

(6.35 ± 0.38)

L

H

W

D

T

OARS XP

Open Air Sense Resistors

Metal Alloy Strip

25

60

95

130

165

195

225

6.0

5.0

4.0

3.0

2.0

0.0

Ambient Temperature (°C)

Power Derating Curve

Note:

The power derating curve is a guidance based on a conser-

vative design model. The OARS XP is a solid metal alloy

construction that can withstand significantly greater operating

temperatures than conservative design models permit. The

resistive alloys can withstand temperatures in exess of 350°C.

Therefore, the system thermal design is a more significant

design parameter due to the heat limitations of solder joints

and/or circuit board substrate materials. Refer to additional

information below.

The thermal image (not a simulation) to the left is of an OARS

XP 2.5 m

Ω running at 5 Watts. Notice the hotpsot is nearly

205°C, but the solder joint is approximately 115°C (FR4 is

rated for 130°C). The unique construction of the OARS XP

isolates the hotspot from the circuit board material preventing

damage. 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. Contact IRC for

more details or for other thermal image test data for specific

resistance values and power levels.

OARS XP R0025 Thermal Image @ 5 Watts

Ambient conditions, No forced air.

OARS-XP Issue May 2009 Sheet 2 of 3