RTO 50
Vishay Sfernice
Power Resistor, Thick Film Technology
FEATURES
• 50 Watt at 25 °C Heatsink Mounted
• Adjusted by sand trimming
• Leaded or surface mount versions
• High power to size ratio
• Non inductive element
Because of the knowledge and experience in Thick Film technology, Vishay Sfernice has been able to develop a high power
resistor in a TO 220 package called RTO 50. The special design of this component allows the dissipation of 50 W when mounted
on a heatsink. The ohmic value is adjusted by sand trimming. This process does not generate hot spots as in laser trimming,
which could lead to microcracks on each side of the curve. This process improves the reliability and the stability of the resistor
and at the same time gives a good overload capability.
DIMENSIONS in millimeters
RTO 50F - LEADED RTO 50C - FOR SURFACE MOUNTING
10.1
Ø 3.6
1.3
4.5
10.1
Ø 3.6
4.5
1.3
RoHS
COMPLIANT
15
12.5
13.7
Ø 0.8
5.08
• Tolerance unless otherwise specifi ed: ± 0.4 mm
2.5
MECHANICAL SPECIFICATIONS
Mechanical Protection Molded
Resistive Element Thick Film
Connections Tinned copper alloy
Weight 2 g max.
DIMENSIONS
Standard Package TO 220
Insulated Case
ENVIRONMENTAL SPECIFICATIONS
Temperature Range - 55 °C to + 155 °C
Climatic Category 55/155/156
Sealing Sealed container
Solder immersion
8.8
• Only for RTO 50 version C = during surface mount soldering, the soldering temperature
profi le must not cause the metal tab of this device to exceed 220 °C.
ELECTRICAL SPECIFICATIONS
Resistance Range 0.010 Ω to 1 MΩ serie E24
Tolerances Standard ± 1 % to ± 10 %
Dissipation and Associated Onto a heatsink
Thermal Resistance 50 W at + 25 °C
and Nominal Power R
free air:
2.25 W at + 25 °C
Temperature Coeffi cient See Performance table
Standard ± 150 ppm/°C
Limiting Element Voltage 300 V
Dielectric Strength
MIL STD 202 (301)
Insulation Resistance ≥ 10
Inductance ≤ 0.1 µH
Critical Resistance 1.8 kΩ
1.8
5.08
12.5
15
2
3
0.3
TH (j-c): 2.6 °C/W
RMS - 1 Minute - 10mA Max
2000 V
6
MΩ
8.8
Document Number: 50035
Revision 30-May-06
For technical questions, contact sfer@vishay.com
www.vishay.com
17
RTO 50
Vishay Sfernice
Power Resistor Thick Film Technology
PERFORMANCE
TESTS CONDITIONS TYPICAL DRIFTS
Us < 1.5 UL
5 cycles - 55 °C to + 155 °C
Load Life NF EN 140 000 Pr at + 25 °C, 1000 hrs. CEI 115_1 ± (1 % + 0.05 Ω)
Humidity (Steady State)
Method 103 B Cond. D
Vibration
Method 204 Cond. D
Terminal Strength
NF EN 140 000Momentary Overload
NF EN 140 000Rapid Temperature Change
CEI 68214 Tests Na
MIL STD 202 ± (0.5 % + 0.05 Ω)
MIL STD 202 ± (0.2 % + 0.05 Ω)
MIL STD 202 ± (0.2 % + 0.05 Ω)
± (0.25 % + 0.05 Ω)
2 Pr/5 s
± (0.5 % + 0.05 Ω)
SPECIAL FEATURES
Resistance Values ≥ 0.010 Ω ≥ 0.015 Ω ≥ 0.1 Ω ≥ 0.5 Ω
Tolerances ± 1 % at ± 10 %
Temperature
Standard ± 900 ppm/°C ± 700 ppm/°C ± 250 ppm/°C ± 150 ppm/°C
Coeffi cient
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 =
[R
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)
R
TH: (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
Example:
R
TH: (c-a) for RTO 50 power rating 13 W at ambient temperature + 30 °C
Thermal resistance R
TH (j-c): 26 °C/W
Considering equation (1) we have:
ΔT
RTH (j-c) + RTH (c-a) = = = 9.6 °C/W
RTH (c-a)
≤ 155 °C - 30 °C ≤ 125 °C
125
ΔT
13
P
≤ 9.6 °C/W - 2.6 °C/W ≤ 7 °C/W
ΔT
TH (j-c) + RTH (c-a)]
(1)
www.vishay.com
18
For technical questions, contact sfer@vishay.com
Document Number: 50035
Revision 30-May-06
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