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 50W 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
4.5
RTO 50C - FOR SURFACE MOUNTING
4.5
10.1
Ø 3.6
10.1
Ø 3.6
1.3
1.3
12.5
15
8.8
12.5
15
8.8
2
13.7
3
1.8
0.3
5.08
Ø 0.8
2.5
• Tolerance unless otherwise specified: ± 0.4mm
5.08
MECHANICAL SPECIFICATIONS
Mechanical Protection
Resistive Element
Connections
Weight
Molded
Thick Film
Tinned copper alloy
2g max.
ELECTRICAL SPECIFICATIONS
Resistance Range
Tolerances Standard
Dissipation and Associated
Thermal Resistance
and Nominal Power
0.010Ω to 1MΩ
± 1% to ± 10%
Onto a heatsink
50W at + 25°C
R
TH
(j-c): 2.6°C/W
free air:
2.25W at + 25°C
Temperature Coefficient
Standard
Limiting Element Voltage
Dielectric Strength
MIL STD 202 (301)
Insulation Resistance
Inductance
Critical Resistance
≥
10
6
MΩ
≤
0.1 µH
1.8 kΩ
See Performance table
± 150ppm/°C
300V
2000V
RMS
- 1 Minute - 10mA Max
DIMENSIONS
Standard Package
TO 220
Insulated Case
ENVIRONMENTAL SPECIFICATIONS
Temperature Range
Climatic Category
Sealing
- 55°C to + 155°C
55/155/156
Sealed container
Solder immersion
Document Number: 50035
Revision 14-Jan-05
For technical questions, contact sfer@vishay.com
www.vishay.com
17
RTO 50
Vishay Sfernice
PERFORMANCE
TESTS
Momentary Overload
Us < 1.5UL
Rapid Temperature Change
5 cycles - 55°C to + 155°C
Load Life
Humidity (Steady State)
Method 103 B Cond. D
Vibration
Method 204 Cond. D
Terminal Strength
Method 211 Cond. A1
CONDITIONS
NF EN 140000
2Pr/5s
NF EN 140000
CEI 68214 Tests Na
NF EN 140000 Pr at + 25°C CEI 115_1
MIL STD 202
MIL STD 202
MIL STD 202
TYPICAL DRIFTS
± (0.25% + 0.05Ω)
Power Resistor Thick Film Technology
± (0.5% + 0.05Ω)
± (1% + 0.05Ω)
± (0.5% + 0.05Ω)
± (0.2% + 0.05Ω)
± (0.2% + 0.05Ω)
SPECIAL FEATURES
Resistance Values
Tolerances
Temperature
Coefficient
Standard
± 900ppm/°C
± 700ppm/°C
≥
0.010Ω
≥
0.015Ω
≥
0.1Ω
± 1% at ± 10%
± 250ppm/°C
± 150ppm/°C
≥
0.5Ω
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=
∆T
(1)
[R
TH
(j-c) + R
TH
(c-a)]
P:
T:
R
TH:
R
TH:
Example:
expressed in W
difference between maximum working temperature and room temperature.
(j-c):
(c-a):
thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal
resistance of the component: (Special Features Table)
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.
R
TH:
(c-a) for RTO 50 power rating 13 W at ambient temperature + 30°C.
Thermal resistance R
TH
(j-c): 25°C/W
Considering equation (1) we have:
∆T
≤
155°C - 30°C
≤
125°C
125
∆T
RTH (j-c) + RTH (c-a) =
=
= 9.6°C/W
13
P
RTH (c-a)
≤
9.6°C/W - 2.6°C/W
≤
7°C/W
www.vishay.com
18
For technical questions, contact sfer@vishay.com
Document Number: 50035
Revision 14-Jan-05
RTO 50
Power Resistor Thick Film Technology
OVERLOADS
The applied voltage must always be lower than the maximum overload voltage of 450V.
The values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink.
Vishay Sfernice
ENERGY CURVE
10
ENERGY IN JOULES
1
0.1
0.01
10
-6
10
-5
10
-4
10
-3
10
-2
OVERLOAD DURATION IN SECONDS
POWER RATING CHART
The temperature of the heatsink should be maintained within the limits specified.
To improve the thermal conductivity, surfaces in contact should be coated with a silicone grease and the torque applied on
the screw for tightening should be around 1Nm.
100
% RATED POWER
75
50
25
0
0
25
40
60
80
100
120
140
155
HEATSINK TEMPERATURE IN DEGREES CELSIUS
MARKING
Model, Style, Resistance Value (in ), Tolerance (in %), Manufacturing Date, VISHAY trademark.
PACKAGING
Tube of 50 units
ORDERING INFORMATION
RTO
MODEL
50
STYLE
F
CONNECTIONS
F: Leaded
C: Surface Mount
100 k½
RESISTANCE VALUE
± 1%
TOLERANCE
± 1%
± 2%
± 5%
± 10%
xxx
CUSTOM DESIGN
Optional
on request:
special TCR,
shap, etc.
Document Number: 50035
Revision 14-Jan-05
For technical questions, contact sfer@vishay.com
www.vishay.com
19
Legal Disclaimer Notice
Vishay
Notice
Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc.,
or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's
terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express
or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness
for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Vishay for any damages resulting from such improper use or sale.
Document Number: 91000
Revision: 08-Apr-05
www.vishay.com
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