RCH
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Revision: 16-Nov-17 1Document Number: 50006
For technical questions, contact: sferfixedresistors@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Power Resistor, for Mounting onto a Heatsink
Thick Film Technology
DESIGN SUPPORT TOOLS
FEATURES
• 5 W to 50 W
• High power rating
• High overload capabilities up to 2500 VRMS
• Wide resistance range from 0.24 to 1 M
• High thermal capacity up to 0.8 °C/W
• Easy mounting
• Reduced size and weight
• High insulation: 106 M
• Material categorization: for definitions of compliance
please see www.vishay.com/doc?99912
Manufactured in cermet thick film technology, these power resistors exhibit remarkable characteristics and the series includes
4 types ranging from 5 W to 50 W. Designed to be mounted onto a heatsink, the resistors can bear high short time overloads
and 3 types of terminations are available. The resistors are non inductive and are particularly suitable for high frequency
operation and cut-out circuits.
Note
• Tolerances unless stated: ± 0.3 mm
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Available
Models
DIMENSIONS in millimeters
MODEL RCH5 RCH10 RCH25 RCH50
L16.6 19 28 47.8
W9 11 14 15.5
H16.4 20.6 27.5 29.5
P Leads Pitch 10.2 12.7 18.3 30.5
F Connection Pitch 11.3 14.3 18.3 39.7
T12.5 15.9 19.8 21.4
S5.357.78
Ø D 2.4 2.4 3.2 3.2
Weight (g) 45712
Ø 2
6
RCH...R
M2
6
RCH...V
W
H
F
S
L
Ø D
P
6
4.8
6
3Ø 2.1
T9
RCH...S
RCH
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Revision: 16-Nov-17 2Document Number: 50006
For technical questions, contact: sferfixedresistors@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
STANDARD ELECTRICAL SPECIFICATIONS
MODEL
RESISTANCE
RANGE
RATED POWER
P25 °C
W
TOLERANCE
± %
TEMPERATURE
COEFFICIENT
± ppm/°C
SERIES
RCH 5 0.24 to 1M 5 1, 2, 5, 10 150, 250 E24 range
RCH 10 0.24 to 1M 10 1, 2, 5, 10 150, 250 E24 range
RCH 25 0.24 to 1M 25 1, 2, 5, 10 150, 250 E24 range
RCH 50 0.24 to 1M 50 1, 2, 5, 10 150, 250 E24 range
MECHANICAL SPECIFICATIONS
Mechanical Protection Insulated case
Resistive Element Cermet
Substrate Alumina
Connections Tinned copper alloy
ENVIRONMENTAL SPECIFICATIONS
Temperature Range -55 °C to +125 °C
Climatic Category 55 / 125 / 56
Flammability
IEC 60695-11-5
2 applications 30 s
separated by 60 s
TECHNICAL SPECIFICATIONS
Dissipation and Associated Onto a heatsink
Power Rating:
Chassis Mounted
Unmounted
5 W to 50 W
2 W to 5.5 W
Temperature Coefficient ± 150 ppm/°C
Insulation Resistance 106 M
Total Inductance 0.1 μH
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload
NF EN140000 CEI 115_1
2 Pr/5 s
US < 1.5 UL
< ± (0.25 % + 0.05 )
Rapid Temperature Change
NF EN140000 125 °C CEI 68215 Test Na
5 cycles
-55 °C to +125 °C
< ± (0.25 % + 0.05 )
Load Life NF EN140000 CEI 115_1
1000 h Pr at +25 °C < ± (0.5 % + 0.05 )
Humidity (Steady State) 56 days RH 95 %
MIL-STD-202 Method 103 B and C < ± (0.5 % + 0.05 )
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Resistance Values < 1 > 1
Standard Tolerances ± 5 %
± 10 %
Standard TCR ± 250 ppm/°C ± 150 ppm/°C
Tolerance on Request ± 1 % to ± 2 %
SPECIAL FEATURES
MODEL RCH 5 RCH 10 RCH 25 RCH 50
Power Rating-Chassis Mounted 5 W 10 W 25 W 50 W
Power Rating-Unmounted 2 W 2.5 W 4 W 5.5 W
Thermal Resistance Rth (j - c) 4.8 °C/W 3.2 °C/W 1.4 °C/W 0.8 °C/W
Limiting Element Voltage (VRMS)160 V 250 V 550 V 1285 V
Max. Overload Voltage (VRMS)320 V 500 V 1100 V 2500 V
Dielectric Strength (VRMS) 50 Hz, 1 min
MIL-STD-202 Method 301 10 mA max. 2000 V 2000 V 3500 V 3500 V
Critical Resistance 5120 6250 12 100 33 024
RCH
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Revision: 16-Nov-17 3Document Number: 50006
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THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
RECOMMENDATIONS FOR MOUNTING ONTO A HEATSINK
• Surfaces in contact must be carefully cleaned.
• The heatsink must have an acceptable flatness: From 0.05 mm to 0.1 mm/100 mm.
• Roughness of the heatsink must be around 6.3 μm. In order to improve thermal conductivity, surfaces in contact (alumina,
heatsink) are coated with a silicone grease (type Sl 340 from Rhône-Poulenc or Dow 340 from Dow Corning).
• The fastening of the resistor to the heatsink is under pressure control of two screws (not supplied).
• In order to improve the dissipation, either forced-air cooling or liquid cooling may be used.
• A low thermal radiation of the case allows several resistors to be mounted onto the same heatsink.
• Do not forget to respect an insulation value between two resistors (dielectric strength in dry air 1 kV/mm).
• In any case the hot spot temperature, measured locally on the case must not exceed 125 °C.
• Tests should be performed by the user.
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 125 °C. The dissipated power is simply calculated by the following ratio:
P: Expressed in W
T: Difference between maximum working temperature and room temperature or fluid cooling temperature.
Rth (j - c): Thermal resistance value measured between resistive layer and outer side of the resistor. It is the thermal
resistance of the component.
Rth (c - h): Thermal resistance value measured between outer side of the resistor and upper side of the heatsink. This is the
thermal resistance of the interface (grease, thermal pad), and the quality of the fastening device.
Rth (h - a): Thermal resistance of the heatsink.
Example:
RTH (c - a) for RCH 25 power rating 20 W at ambient temperature +50 °C
Thermal resistance RTH (j - c): 2.5 °C/W
Considering equation (1) we have:
T = 125 °C - 50 °C 75 °C
RTH (j - c) = 1.4 °C/W (Special Features)
RTH (j - c) + RTH (c - h) + RTH (h - a) = = = 3.75 °C/W
RTH (c - h) + RTH (h - a) 3.75 °C/W - 1.4 °C/W 2.35 °C/W
with a thermal grease RTH (c - h) = 1 °C/W, we need a heatsink with RTH (h - a) = 1.35 °C/W
Tightening Torque
on heatsink
RCH 5 RCH 10 RCH 25 RCH 50
0.5 Nm 0.6 Nm 0.7 Nm 1 Nm
PT
RTH (j - c) RTH (c - h) RTH (h - a)
++
-------------------------------------------------------------------------------------------
1
=
T
P
-------
75
20
-----
RCH
www.vishay.com Vishay Sfernice
Revision: 16-Nov-17 4Document Number: 50006
For technical questions, contact: sferfixedresistors@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
OVERLOADS
The applied voltage must always be lower than the
maximum overload voltage as shown in the special features
table.
The values indicated on the graph below are applicable to
resistors in air or mounted onto a heatsink.
ENERGY CURVE
POWER CURVE
POWER RATING
For resistors mounted onto heatsink and thermal resistance
of 1 °C/W.
To improve the thermal conductivity, surfaces in contact
should be coated with a silicone grease.
MARKING
Model, style, resistance value (in ), tolerance (in %),
manufacturing date, Vishay Sfernice trademark.
0.01
0.1
1
10
100
ENERGY IN JOULES
OVERLOAD DURATION IN s
RCH50
RCH25
RCH10
RCH5
10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
10
100
1000
10 000
100 000
1 000 000
POWER IN W
OVERLOAD DURATION IN s
RCH50
RCH25
RCH10
RCH5
10-7 10-6 10-5 10-4 10-3 10-2 10-1 100
0
25
50
75
100
RATED POWER IN %
0
AMBIENT TEMPERATURE IN °C
20 40 60 80 100 120 140
RCH 5
RCH 10
RCH 25
RCH 50
RCH
www.vishay.com Vishay Sfernice
Revision: 16-Nov-17 5Document Number: 50006
For technical questions, contact: sferfixedresistors@vishay.com
THIS DOCUMENT IS SUBJECT TO CHANGE WITHOUT NOTICE. THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT
ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
ORDERING INFORMATION
RCH 25 3.3 k± 5 % R xxx
MODEL STYLE RESISTANCE VALUE TOLERANCE
Optional
± 1 %
± 2 %
± 5 %
± 10 %
CONNECTIONS
Optional
S: flat with hole
R: round lead
V: M2 screw
CUSTOM DESIGN
Optional
GLOBAL PART NUMBER INFORMATION
GLOBAL
MODEL SIZE LEADS OHMIC VALUE TOLERANCE PACKAGING SPECIAL
RCH 05
10
25
50
R = round lead
V = M2 screw
S = flat with hole
The first four digits are
significant figures and the
last digit specifies the
number of zeros to follow.
R designates decimal point.
4R700 = 4.7
48701 = 48 700
R0100 = 0.01
R6800 = 0.68
27000 = 2700 = 2.7 k
F = 1 %
G = 2 %
J = 5 %
K = 10 %
S06 = bag
25 pieces
As applicable
Ex = XXX
10S3300J03C HR 0S6
Legal Disclaimer Notice
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Revision: 08-Feb-17 1Document Number: 91000
Disclaimer
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