RCH
www.vishay.com
Vishay Sfernice
Power Resistor, for Mounting Onto a Heatsink
Thick Film Technology
FEATURES
• Compliant with requirement #26 of
NF-EN45545-2
• 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
LINKS TO ADDITIONAL RESOURCES
• Easy mounting
• Reduced size and weight
3D 3D
• High insulation: 106 M
3D Models
• 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.
DIMENSIONS in millimeters
RCH...R
RCH...V
M2
Ø2
RCH...S
6
H
6
W
6
Ø 2.1
3
4.8
S
L
P
F
6
ØD
T
MODEL
9
RCH5
RCH10
RCH25
L
16.6
19
28
47.8
W
9
11
14
15.5
H
16.4
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
T
12.5
15.9
19.8
21.4
S
5.3
5
7.7
8
ØD
2.4
2.4
3.2
3.2
4
5
7
12
Weight (g)
RCH50
Note
• Tolerances unless stated: ± 0.3 mm
Revision: 02-Sep-2020
Document Number: 50006
1
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
RCH
www.vishay.com
Vishay Sfernice
STANDARD ELECTRICAL SPECIFICATIONS
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
MODEL
MECHANICAL SPECIFICATIONS
TECHNICAL SPECIFICATIONS
Mechanical Protection
Dissipation and Associated
Insulated case
Resistive Element
Cermet
Substrate
Alumina
Connections
Tinned copper alloy
ENVIRONMENTAL SPECIFICATIONS
Temperature Range
Flammability
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
-55 °C to +125 °C
Climatic Category
Onto a heatsink
Power Rating:
Chassis Mounted
Unmounted
55 / 125 / 56
IEC 60695-11-5
2 applications 30 s
separated by 60 s
PERFORMANCE
TESTS
Momentary Overload
Rapid Temperature Change
Load Life
Humidity (Steady State)
CONDITIONS
REQUIREMENTS
NF EN140000 CEI 115_1
2 Pr/5 s
US < 1.5 UL
< ± (0.25 % + 0.05 )
NF EN140000 125 °C CEI 68215 Test Na
5 cycles
-55 °C to +125 °C
< ± (0.25 % + 0.05 )
NF EN140000 CEI 115_1
1000 h Pr at +25 °C
< ± (0.5 % + 0.05 )
56 days RH 95 %
MIL-STD-202 Method 103 B and C
< ± (0.5 % + 0.05 )
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
1
±5%
± 10 %
Standard Tolerances
Standard TCR
± 250 ppm/°C
± 150 ppm/°C
Tolerance on Request
± 1 % to ± 2 %
SPECIAL FEATURES
MODEL
RCH 5
RCH 10
RCH 25
Power Rating-Chassis Mounted
5W
10 W
25 W
50 W
Power Rating-Unmounted
2W
2.5 W
4W
5.5 W
Thermal Resistance Rth (j - c)
RCH 50
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
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
Revision: 02-Sep-2020
Document Number: 50006
2
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
RCH
www.vishay.com
Vishay Sfernice
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).
Tightening Torque
on heatsink
RCH 5
RCH 10
RCH 25
RCH 50
0.5 Nm
0.6 Nm
0.7 Nm
1 Nm
• 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:
1
T
P = ------------------------------------------------------------------------------------------R TH (j - c) + R TH (c - h) + R TH (h - a)
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)
T
RTH (j - c) + RTH (c - h) + RTH (h - a) = ------- = 75
----- = 3.75 °C/W
P
20
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
Revision: 02-Sep-2020
Document Number: 50006
3
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
RCH
www.vishay.com
Vishay Sfernice
OVERLOADS
POWER RATING
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.
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.
100
ENERGY CURVE
RATED POWER IN %
RCH 5
RCH 10
ENERGY IN JOULES
100
RCH50
RCH25
10
1
RCH10
RCH5
0.1
75
RCH 25
RCH 50
50
25
0
0
0.01
10-7
20
40
60
80
100
120
140
AMBIENT TEMPERATURE IN °C
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
10
0
OVERLOAD DURATION IN s
MARKING
Model, style, resistance value (in ), tolerance (in %),
manufacturing date, Vishay Sfernice trademark.
POWER CURVE
1 000 000
POWER IN W
100 000
RCH50
RCH25
10 000
1000
RCH10
RCH5
100
10
10-7
10-6
10-5
10-4
10-3
10-2
10-1
100
OVERLOAD DURATION IN s
Revision: 02-Sep-2020
Document Number: 50006
4
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
RCH
www.vishay.com
Vishay Sfernice
ORDERING INFORMATION
RCH
25
3.3 k
±5%
R
xxx
MODEL
STYLE
RESISTANCE VALUE
TOLERANCE
CONNECTIONS
CUSTOM DESIGN
Optional
±1%
±2%
±5%
± 10 %
Optional
S: flat with hole
R: round lead
V: M2 screw
Optional
GLOBAL PART NUMBER INFORMATION
R
GLOBAL
MODEL
RCH
Revision: 02-Sep-2020
C
H
1
0
S
3
3
0
0
0
J
S
0
6
3
SIZE
LEADS
OHMIC VALUE
TOLERANCE
PACKAGING
SPECIAL
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
Document Number: 50006
5
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
Legal Disclaimer Notice
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Vishay
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Revision: 01-Jan-2023
1
Document Number: 91000