Document Number: 50046 For technical questions, contact: sfer@vishay.com www.vishay.com
Revision: 17-Sep-09 53
Power Resistor for Mounting onto a Heatsink
Thick Film Technology
RPH 100
Vishay Sfernice
FEATURES
•High power rating
•Low thermal radiation of the case
•Wide ohmic value range
•Easy mounting
•High overload capabilities
•Reduced size and weight
•Compliant to RoHS directive 2002/95/EC
This new style has been developed as an extension to RCH range. Through the use of thick film technology, a non-inductive
solution for power resistors is available which are rated up to 100 W at + 25 °C. The terminations position prevents any risk of an
electrical arc to the heatsink. This resistor series can replace and offer advantages to standard wirewound devices.
DIMENSIONS in millimeters
MECHANICAL SPECIFICATIONS
Mechanical Protection Insulated case
Substrate Alumina on metallic
base of nickel coated
aluminum
Resistive Element Cermet
End Connections V connections:
Screws M4 x 6
Tightening Torque Connections 1 Nm
Tightening Torque Heatsink 3 Nm
Weight 60 g
ENVIRONMENTAL SPECIFICATIONS
Thermal Resistance Rth (j - c) 0.55 °C/W
Temperature Range - 55 °C to + 125 °C
Climatic Category 55/125/56
65.2 ± 0.4
35
25.6 ± 0.4 37 46.7
42.4 ± 0.5
16.6 18.5 ± 0.4 21.15 ± 0.7
4
Ø 4.2
Ø 4.2
V Connections
Tolerance unless otherwise specified: ± 0.3 mm
RPH 100
ELECTRICAL SPECIFICATIONS
Resistance Range
0.092
Ω
to 1 M
Ω
E24 series
Tolerances
± 1 % to ± 10 %
Power Rating:
Continuous
100 W at 25 °C
chassis mounted 0.45 °C/W
10 W at 25 °C
Free air
Momentary
400 W at 25 °C for 5 s
Temperature Coefficient
Standard
± 300 ppm/°C < 1
Ω
± 150 ppm/°C > 1
Ω
Limiting Element Voltage U
L
1900 V
RMS
Dielectric Strength MIL STD 202
5 kV
RMS
1 min 10 mA max.
Insulation Resistance
> 10
6
M
Ω
Inductance
< 0.1 µH
RPH 100
Vishay Sfernice Power Resistor for Mounting onto a Heatsink
Thick Film Technology
www.vishay.com For technical questions, contact: sfer@vishay.com Document Number: 50046
54 Revision: 17-Sep-09
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 ratios:
P: Expressed in W
T: Difference between maximum working temperature and room 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: 0.55 °C/W.
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 RPH 100 power rating 80 W at ambient temperature + 40 °C.
Thermal resistance Rth (j - c): 0.55 °C/W
Considering equation (1) we have:
ΔT ≤ 125 °C - 40 °C ≤ 85 °C
Rth (j - c) + Rth (c - a) = = = 1.06 °C/W
Rth (c - a) ≤ 1.06 °C/W - 0.55 °C/W ≤ 0.51 °C/W
RECOMMENDATIONS FOR MOUNTING ONTO A HEATSINK
Surfaces in contact must be carefully cleaned.
The heatsink must have an acceptable fl atness: 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) should be coated with a silicone grease (type
SI 340 from Rhône-Poulenc or Dow 340 from Dow Corning).
The fastening of the resistor to the heatsink is under pressure control of four screws (not supplied).
Tightening torque: 3 Nm
In order to improve the dissipation, either forced-air cooling or liquid cooling may be used.
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Short Time Overload NF EN 140000 CEI 115_1
4 Pn/5 s US < 2 UL
< ± (0.25 % + 0.05 Ω)
Rapid Temperature Change NF EN 140000 CEI 68214 Test Na
5 cycles - 55 °C + 125 °C
< ± (0.25 % + 0.05 Ω)
Load Life (Chassis Mounted 0.45 °C/W)
NF EN 140000
Pn at 25 °C 1000 h
< ± (0.5 % + 0.05 Ω)
Humidity (Steady State) MIL STD 202 Method 103 B Test D
56 days 95 % RH
< ± (0.5 % + 0.05 Ω)
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Ohmic Value < 1 Ω > 1 Ω
Standard Tolerance ± 5 % ± 5 %
Standard TCR ± 300 ppm/°C ± 150 ppm/°C
Tolerance On Request ± 1 % - ± 2 %
PΔT
Rth (j - c) Rth (c - a)
+[]
-----------------------------------------------------=1()
ΔT
P
------- 85
80
------
Document Number: 50046 For technical questions, contact: sfer@vishay.com www.vishay.com
Revision: 17-Sep-09 55
RPH 100
Power Resistor for Mounting onto a Heatsink
Thick Film Technology Vishay Sfernice
Do not forget to respect an insulation value between two resistors (dielectric strength in dry air 1 kV/mm).
OVERLOADS
In any case the applied voltage must be lower than 2 Un.
Umax. < 2 Un < 3800 V.
Short time overload: 4 Pn/5 s.
Accidental overload: The values indicated on the graph below are applicable to resistors in air or mounted onto a heatsink.
POWER RATING CHART
For resistor mounted onto a heatsink with thermal resistance of 0.45 °C/W.
MARKING
Series. style, ohmic value (in Ω). tolerance (in %), manufacturing date, SFERNICE trade mark.
ORDERING INFORMATION
RPH 100 3.3 kΩ± 5 % V XXX
MODEL STYLE RESISTANCE VALUE TOLERANCE
Optional
± 1 %
± 2 %
± 5 %
CONNECTIONS
V: M4 screw
CUSTOM DESIGN
Options
on request
TCR, shape,
etc.
OVERLOAD DURATION IN s
ENERGY IN JOULES
0.1
1
10
100
1.10 1.10
-7 -6
ENERGY CURVE
1000
1.10-5 1.10-4 1.10-3 1.10-2 1.10-1 1
AMBIENT TEMPERATURE IN °C
% RATED POWER
80
60
40
20
0
0 20 40 60 80 100 120 140
100
RPH 100
Vishay Sfernice Power Resistor for Mounting onto a Heatsink
Thick Film Technology
www.vishay.com For technical questions, contact: sfer@vishay.com Document Number: 50046
56 Revision: 17-Sep-09
GLOBAL PART NUMBER INFORMATION
GLOBAL
MODEL SIZE LEADS OHMIC VALUE TOLERANCE PACKAGING SPECIAL
RPH 100 V = M4 screw The firts four digits are
significant figures and the
last digit specifies the
number of zeros to follow.
R designates decimal point.
48R70 = 48.7 Ω
48701 = 48700 Ω
10002 = 100 kΩ
R0100 = 0.01 Ω
R6800 = 0.68 Ω
27000 = 2700 Ω = 2K7 Ω
F = 1 %
G = 2 %
J = 5 %
K = 10 %
B = Box 5 pieces As applicable
Ex = XXX
100V100 2 BP HR 0J
Document Number: 91000 www.vishay.com
Revision: 18-Jul-08 1
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therein, which apply to these products.
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