RCH
www.vishay.com
Vishay Sfernice
Power Resistor, for Mounting onto a Heatsink
Thick Film Technology
FEATURES
• 5 W to 50 W
• High power rating
• High overload capabilities up to 2500 V
RMS
• Wide resistance range from 0.24
to 1 M
• High thermal capacity up to 0.8 °C/W
• Easy mounting
• Reduced size and weight
DESIGN SUPPORT TOOLS
Models
Available
click logo to get started
• High insulation: 10
6
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.
DIMENSIONS
in millimeters
RCH...R
Ø2
RCH...V
M2
RCH...S
6
H
W
6
3
Ø 2.1
6
S
L
F
P
4.8
6
ØD
T
9
MODEL
L
W
H
P Leads Pitch
F Connection Pitch
T
S
ØD
Weight (g)
Note
• Tolerances unless stated: ± 0.3 mm
RCH5
16.6
9
16.4
10.2
11.3
12.5
5.3
2.4
4
RCH10
19
11
20.6
12.7
14.3
15.9
5
2.4
5
RCH25
28
14
27.5
18.3
18.3
19.8
7.7
3.2
7
RCH50
47.8
15.5
29.5
30.5
39.7
21.4
8
3.2
12
Revision: 16-Nov-17
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
RATED POWER
P
25 °C
W
5
10
25
50
TEMPERATURE
COEFFICIENT
± ppm/°C
150, 250
150, 250
150, 250
150, 250
STANDARD ELECTRICAL SPECIFICATIONS
MODEL
RCH 5
RCH 10
RCH 25
RCH 50
RESISTANCE
RANGE
0.24 to 1M
0.24 to 1M
0.24 to 1M
0.24 to 1M
TOLERANCE
±%
1, 2, 5, 10
1, 2, 5, 10
1, 2, 5, 10
1, 2, 5, 10
SERIES
E24 range
E24 range
E24 range
E24 range
MECHANICAL SPECIFICATIONS
Mechanical Protection
Resistive Element
Substrate
Connections
Insulated case
Cermet
Alumina
Tinned copper alloy
TECHNICAL SPECIFICATIONS
Dissipation and Associated
Power Rating:
Chassis Mounted
Unmounted
Temperature Coefficient
Insulation Resistance
Total Inductance
Onto a heatsink
5 W to 50 W
2 W to 5.5 W
± 150 ppm/°C
10
6
M
0.1 μH
ENVIRONMENTAL SPECIFICATIONS
Temperature Range
Climatic Category
Flammability
-55 °C to +125 °C
55 / 125 / 56
IEC 60695-11-5
2 applications 30 s
separated by 60 s
PERFORMANCE
TESTS
Momentary Overload
CONDITIONS
NF EN140000 CEI 115_1
2 Pr/5 s
U
S
< 1.5
U
L
NF EN140000 125 °C CEI 68215 Test Na
5 cycles
-55 °C to +125 °C
NF EN140000 CEI 115_1
1000 h Pr at +25 °C
56 days RH 95 %
MIL-STD-202 Method 103 B and C
REQUIREMENTS
< ± (0.25 % + 0.05
)
Rapid Temperature Change
Load Life
Humidity (Steady State)
< ± (0.25 % + 0.05
)
< ± (0.5 % + 0.05
)
< ± (0.5 % + 0.05
)
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Resistance Values
Standard Tolerances
Standard TCR
Tolerance on Request
± 250 ppm/°C
± 1 % to ± 2 %
<1
±5%
± 10 %
± 150 ppm/°C
>1
SPECIAL FEATURES
MODEL
Power Rating-Chassis Mounted
Power Rating-Unmounted
Thermal Resistance R
th (j - c)
Limiting Element Voltage (V
RMS
)
Max. Overload Voltage (V
RMS
)
Dielectric Strength (V
RMS
) 50 Hz, 1 min
MIL-STD-202 Method 301 10 mA max.
Critical Resistance
RCH 5
5W
2W
4.8 °C/W
160 V
320 V
2000 V
5120
RCH 10
10 W
2.5 W
3.2 °C/W
250 V
500 V
2000 V
6250
RCH 25
25 W
4W
1.4 °C/W
550 V
1100 V
3500 V
12 100
RCH 50
50 W
5.5 W
0.8 °C/W
1285 V
2500 V
3500 V
33 024
Revision: 16-Nov-17
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
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
0.5 Nm
RCH 10
0.6 Nm
RCH 25
0.7 Nm
RCH 50
1 Nm
Vishay Sfernice
• 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.
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.
R
th (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.
R
th (h - a)
: Thermal resistance of the heatsink.
Example:
R
TH (c - a)
for RCH 25 power rating 20 W at ambient temperature +50 °C
Thermal resistance R
TH (j - c)
: 2.5 °C/W
Considering equation
(1)
we have:
T
=
125 °C - 50 °C
75 °C
R
TH (j - c)
= 1.4 °C/W (Special Features)
R
TH (j - c)
+ R
TH (c - h)
+ R
TH (h - a)
=
------
=
----
= 3.75 °C/W
-
-
R
TH (c - h)
+ R
TH (h - a)
3.75 °C/W - 1.4 °C/W
2.35 °C/W
with a thermal grease R
TH (c - h)
= 1 °C/W, we need a heatsink with R
TH (h - a)
= 1.35 °C/W
T
P
75
20
Revision: 16-Nov-17
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
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.
Vishay Sfernice
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.
100
ENERGY CURVE
RATED POWER IN %
100
RCH 5
RCH 10
75
RCH 25
RCH 50
50
ENERGY IN JOULES
10
RCH50
RCH25
1
RCH10
RCH5
25
0.1
0
0
20
40
60
80
100
120
140
0.01
10
-7
AMBIENT TEMPERATURE IN °C
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
OVERLOAD DURATION IN s
MARKING
Model, style, resistance value (in
),
tolerance (in %),
manufacturing date, Vishay Sfernice trademark.
POWER CURVE
1 000 000
100 000
POWER IN W
10 000
RCH50
RCH25
1000
RCH10
RCH5
100
10
10
-7
10
-6
10
-5
10
-4
10
-3
10
-2
10
-1
10
0
OVERLOAD DURATION IN s
Revision: 16-Nov-17
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
3.3 k
±5%
TOLERANCE
Optional
±1%
±2%
±5%
± 10 %
R
CONNECTIONS
Optional
S: flat with hole
R: round lead
V: M2 screw
xxx
CUSTOM DESIGN
Optional
ORDERING INFORMATION
RCH
MODEL
25
STYLE
RESISTANCE VALUE
GLOBAL PART NUMBER INFORMATION
R
C
H
1
0
S
3
3
0
0
0
J
S
0
6
3
GLOBAL
MODEL
RCH
SIZE
05
10
25
50
LEADS
R
= round lead
V
= M2 screw
S
= flat with hole
OHMIC VALUE
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
TOLERANCE
F
=1%
G
=2%
J
=5%
K
= 10 %
PACKAGING
S06
= bag
25 pieces
SPECIAL
As applicable
Ex =
XXX
Revision: 16-Nov-17
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
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