Datasheet

www.vishay.com
15
RTO 20
Vishay Sfernice
Document Number: 50005
Revision 14-Jan-05
For technical questions, contact [e-mail]
TESTS CONDITIONS TYPICAL DRIFTS
Momentary Overload NF EN 140000 CEI 115_1
2Pr/5s ± (0.25% + 0.005Ω)
Us < 1.5UL
Rapid Temperature Change NF EN 140000 CEI 68214 Test Na
5 cycles ± (0.5% + 0.005Ω)
- 55°C to + 135°C
Load Life NF EN 140000 CEI 115_1
1000h Pr at + 25°C ± (1% + 0.005Ω)
Humidity (Steady State) NF EN 140000
56 days R.H. 95% ± (0.5% + 0.005Ω)
High Temperature Exposure
NF EN 140000
1000h - 40% Pr at + 100°C ± (0.5% + 0.005Ω)
Vibration MIL STD 202, Method 204 C Test D ± (0.2% + 0.005Ω)
Terminal Strength MIL STD 202, Method 211 Test A1 ± (0.2% + 0.005
Ω)
PERFORMANCE
Power Resistor Thick Film Technology
P: expressed in W
∆T: difference between maximum working temperature and room temperature.
R
TH: (j-c): thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal
resistance of the component: (Special Features Table)
RTH: (c-a): thermal resistance value measured between outer side of the resistor and room temperature. It is the
thermal resistance of the heatsink itself (type, shape) and the quality of the fastening device.
∆T
[RTH (j-c) + RTH (c-a)]
(1)
CHOICE OF THE HEATSINK
The user must choose according to the working conditions of the component (power, room temperature).
Maximum working temperature must not exceed 155°C. The dissipated power is simply calculated by the following ratio:
P =
Resistance Values ≥ 0.01 ≥0.015 ≥ 0.1 ≥ 0.5
Tolerances ± 1% at ± 10%
± 900ppm/°C ± 700ppm/°C ± 250ppm/°C ± 150ppm/°C
SPECIAL FEATURES
Typical Temperature
Coefficient
(- 55°C/+ 155°C) range
Note: For very low ohmic values, TC for information
Example:
RTH: (c-a) for RTO 20 power rating 10W at ambient temperature + 25°C.
Thermal resistance R
TH (j-c): 6.5°C/W
Considering equation (1) we have:
∆T = 155°C - 25°C = 130°C
R
TH (j-c) + RTH (c-a) = = = 13°C/W
R
TH (c-a) = 13°C/W - 6.5°C/W = 6.5°C/W
∆T
P
130
10