RPS 500
www.vishay.com
Vishay Sfernice
Revision: 22-Nov-12
2
Document Number: 50047
For technical questions, contact: sfer@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
Note
(1)
Resistors are not tested and guaranteed in cycling conditions
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 tightened at 4 Nm for full power
availability.
• The following accessories are supplied with each product: 2 off CHC M4 x 16/16 class 8.8 for heatsink mounting,
2 off TH M4 x 6/6 and 2 M4 contact lock washers for connections.
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
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: 0.11 °C/W.
R
TH (c - a)
: Thermal resistance value measured between outer side of the resistor and room temperature. It is the thermal
resistance of the heatsink, depending on the heatsink itself (type, shape) and the quality of the fastening device.
PERFORMANCE
TESTS CONDITIONS REQUIREMENTS
Momentary Overload
EN 60115-1
2 Pr/10 s
U
L
= 5000 V
< ± (0.25 % + 0.05 )
Rapid Temperature Change
IEC 60115-1/IEC60068-2-14 Test Na
5 cycles - 55 °C to + 125 °C
< ± (0.25 % + 0.05 )
Load Life
IEC 60115-1
Pr (i.e. 500 W)/1000 h/70 °C (no cycling)
(1)
< ± (0.5 % + 0.05 )
Humidity (Steady State)
MIL STD 202 Method 103 B and D
56 days 95 % RH/40 °C
< ± (0.5 % + 0.05 )
RESISTANCE VALUE IN RELATION TO TOLERANCE AND TCR
Resistance Values 1 1
Standard Tolerances ± 5 %
Standard TCR (- 55 °C to + 125 °C) ± 300 ppm/°C ± 150 ppm/°C
Tolerance on Request ± 1 %, ± 2 %, 10 %
Tightening Torque on Heatsink
RPS 500
4 Nm
P =
T
R
TH (j - c)
+ R
TH (c - a)
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