RTO 20
4.5
1.3
8.8
Ø 0.8
10.1
13.7
12.5
5.08
15
Ø 3.6
2.5
4.5
1.3
8.8
10.1
12.5
5.08
15
Ø 3.6
0.3
1.8
3
2
Vishay Sfernice
Power Resistor Thick Film Technology
The well known TO 220 package is compact and easy to
mount.
DIMENSIONS in millimeters
RTO 20F - LEADED RTO 20C - FOR SURFACE MOUNTING
FEATURES
• 20 Watt at 25°C Heatsink Mounted
• High Power Dissipation to size ratio
• Wide Resistance Range
• Negligible Inductance
• Easy Mounting
• TO220 package: Compact and easy to mount.
Two versions of this thick film resistor are available:
• A Radial Leaded version for PCB Mounting.
• A Flat Lead version for Surface Mounting.
MECHANICAL SPECIFICATIONS
Mechanical Protection Insulated Case
Resistive Element Thick Film
Connections Tinned copper
Weight
2g max.
DIMENSIONS
Standard Package TO 220
Insulated case
ENVIRONMENTAL SPECIFICATIONS
Temperature Range - 55°C to + 155°C
Climatic Category
Sealing Sealed container
Solder immersion
www.vishay.com
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55/155/56
• Tolerance unless otherwise specified: ± 0.4mm
ELECTRICAL SPECIFICATIONS
Resistance Range 0.010Ω to 1MΩ
Tolerances (Standard)
Dissipation and Associated:
Thermal Resistance
and Nominal Power RTH (j-c): 6.5°C/W
free air:
2W at + 25°C
Temperature Coefficient
Standard ± 150ppm/°C
Limiting Element Voltage 250V
Dielectric Strength
MIL STD 202 (Between Terminals and Heatsink)
Insulation
Inductance
Critical Resistance
For technical questions, contact sfer@vishay.com
Resistance ≥ 106 MΩ
± 1% to ± 10%
Onto a heatsink
20W at + 25°C
See Performance table
2000VRMS - 1 minute - 10mA Max
≤ 0.1 µH
3.12 kΩ
Document Number: 50005
Revision 14-Jan-05
RTO 20
Power Resistor Thick Film Technology
Vishay Sfernice
PERFORMANCE
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
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
NF EN 140000
Ω)
SPECIAL FEATURES
Resistance Values ≥ 0.01 ≥0.015 ≥ 0.1 ≥ 0.5
Tolerances ± 1% at ± 10%
Typical Temperature
Coefficient
± 900ppm/°C ± 700ppm/°C ± 250ppm/°C ± 150ppm/°C
(- 55°C/+ 155°C) range
Note: For very low ohmic values, TC for information
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
[RTH (j-c) + RTH (c-a)]
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.
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:
R
R
∆T = 155°C - 25°C = 130°C
130
TH (j-c) + RTH (c-a) = = = 13°C/W
TH (c-a) = 13°C/W - 6.5°C/W = 6.5°C/W
∆T
P
10
(1)
Document Number: 50005
Revision 14-Jan-05
For technical questions, contact sfer@vishay.com
www.vishay.com
15
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