USR UNR 4-3425
Powertron
FEATURES
•
•
•
•
•
Resistances from 0.05Ohm to 500Ohms
Power Rating to 50Watt
Resistance Tolerances to ±0.01%
TCR to ±1ppm/K
Load Stability to 0.01%
TABLE 1—SPECIFICATIONS
TYPE
Resistance Range
Power Rating
Free air 70°C
With heatsink
USR 4-3425
UNR 4-3425
0.05 to 650 Ohms
other resistance values upon request / power rating depending
on resistance value
3W (available with heat sink on backside: 5W)
30W
50W
Tolerances
from 0.05 Ohms
from 10.0 Ohms
from 50.0 Ohms
Thermal Resistance
Stability (1000h)
Shelf Life Stability
Temperature Coefficient
Voltage Proof
Maximum Current
Thermal EMF
Operating Temperature Range
Resistor Material
Substrate
Housing
Connector Material
Terminals
Max. Torque
Notes
0.1% / 0.25% / 0.5% / 1%
0.05% / 0.1% / 0.25% / 0.5% / 1%
0.01% / 0.02% / 0.05% / 0.1% / 0.25% / 0.5% / 1%
3.5 K/W
2.1 K/W
0.01%
25ppm / ∆R after 1 year
50ppm / ∆R after 3 years
max. ±5ppm/K (-55 to 155°C)
typ. ±3ppm/K (-55 to 125°C)
upon request ±1ppm/K (0 to 60°C)
750 VDC
15A
< 0.1µV/K
-55 to 155°C
NiCr-Foil
Al
2
O
3
Epoxy + Al-heatsink
Cu / tinned
4
1 Nm
Specially designed for ap-
plications with fast changing
electrical load
AlN
ORDERING INFORMATION
Part Number - Resistance - Contact - Tolerance - TCR
USR 4-3425 10Ohms D 0.5% 3ppm
Document No.: 64223
Revision: 24-04-2013
For technical questions,
contact
powertron@vishaypg.com
www.powertron.de
1
USR UNR 4-3425
Powertron
FIGURE 1—TEMPERATURE COEFFICIENT
200
100
0
∆R/R
(ppm)
-100
-200
-300
-400
-500
-600
-700
-75
-50
-25
0
25
50
Temperature (°C)
75
100
125
Nominal Spread
±2.3ppm/K
150
Nominal
∆R/R
Nominal Spread
±2.3ppm/K
FIGURE 2—DERATING
Power Rating Notes -
The U-Series Resistors must be attached to a suitable heatsink.
The maximum internal resistor temperature is 155°C.
To specify an appropriate heatsink use the following formula :
Power (% from
nominal power)
120
100
80
60
40
20
0
25
50
85
100
115
130
145
155
R
qH
= T
MAX
- ( P x R
qR
) - T
A
P
Where:
R
qH
= Thermal Resistance of Heatsink ( K/W )
R
qR
= Thermal Resistance of Resistor ( K/W )
T
MAX
= Maximum Temperature of Resistor
T
A
= Ambient Temperature of Heatsink ( °C )
P = Power Through Resistor ( W )
Temperature of the backplate(°C)
FIGURE 3—DIMENSIONS
in mm (inches)
Dimension
A
±2.0 (±0.079)
B
±0.3 (±0.012)
C
±0.2 (±0.008)
D
±0.2 (±0.008)
E
±0.1 (±0.004)
F
±0.2 (±0.008)
G
±0.1 (±0.004)
H
±0.1 (±0.004)
I
±0.2 (±0.008)
J
±0.2 (±0.008)
K
±0.1 (±0.004)
L
±0.1 (±0.004)
M
±0.2 (±0.008)
50.00 (1.97)
34.00 (1.34)
25.00 (0.98)
10.00 (0.39)
5.00 (0.20)
17.80 (0.70)
Ø3.50 (Ø0.14)
Ø0.8 (Ø0.031)
27.50 (1.08)
17.50 (0.69)
2.00 (0.08)
5.50 (0.22)
3.00 (0.12)
www.powertron.de
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For technical questions,
contact
powertron@vishaypg.com
Document No.: 64223
Revision: 24-04-2013
Legal Disclaimer Notice
Vishay Precision Group
Disclaimer
ALL PRODUCTS, PRODUCT SPECIFICATIONS AND DATA ARE SUBJECT TO CHANGE WITHOUT NOTICE.
Vishay Precision Group, Inc., its affiliates, agents, and employees, and all persons acting on its or their
behalf (collectively, “Vishay Precision Group”), disclaim any and all liability for any errors, inaccuracies or
incompleteness contained herein or in any other disclosure relating to any product.
The product specifications do not expand or otherwise modify Vishay Precision Group’s terms and
conditions of purchase, including but not limited to, the warranty expressed therein.
Vishay Precision Group makes no warranty, representation or guarantee other than as set forth in the terms
and conditions of purchase.
To the maximum extent permitted by applicable law, Vishay Precision
Group disclaims (i) any and all liability arising out of the application or use of any product, (ii) any and
all liability, including without limitation special, consequential or incidental damages, and (iii) any and
all implied warranties, including warranties of fitness for particular purpose, non-infringement and
merchantability.
Information provided in datasheets and/or specifications may vary from actual results in different
applications and performance may vary over time. Statements regarding the suitability of products for
certain types of applications are based on Vishay Precision Group’s knowledge of typical requirements that
are often placed on Vishay Precision Group products. It is the customer’s responsibility to validate that a
particular product with the properties described in the product specification is suitable for use in a particular
application.
No license, express, implied, or otherwise, to any intellectual property rights is granted by this document, or
by any conduct of Vishay Precision Group.
The products shown herein are not designed for use in life-saving or life-sustaining applications unless
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Precision Group for any damages arising or resulting from such use or sale. Please contact authorized
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Product names and markings noted herein may be trademarks of their respective owners.
Document No.: 63999
Revision: 27-Apr-2011
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