USR UNR 4-3425 3825 4020
Powertron
•
•
•
•
•
Resistances from 0.05Ohm to 500Ohms
Power Rating to 50Watt
Resistance Tolerances to ±0.01%
TCR to ±1ppm/K
Load Stability to 0.01%
SPECIFICATIONS
Type
Resistance Range
Power rating
free air 70°C
for 3825H
with heatsink
Thermal Resistance Rthj-c
Tolerances
from 0.05 Ohms
from 10.0 Ohms
from 50.0 Ohms
Stability
Shelf Life Stability
Temperature Coefficient
USR 4-
3425 3825
USR 4-
4020
0.05 to 500 Ohms
UNR 4-
3425 3825
UNR 4-
4020
0.05 to 400 Ohms
other resistance values upon request / power rating depending on resistance value
3W
5W
30 W
3.5 K/W
2.5 W
30 W
3.6 K/W
3W
5W
50 W
2.1 K/W
2.5 W
50 W
2.2 K/W
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%
0.01%
25ppm / ∆R after 1 year
50ppm / ∆R after 3 year
max. ±5ppm/K (-55 to 155°C)
typ. ±3ppm/K (-55 to 125°C)
upon request ±1ppm/K (0 to 60°C)
750 VDC
15 A
< 0.1µV/K
-55 to 155°C
NiCr-Foil
Al
2
O
3
Epoxy + Al-heatsink
Cu tinned
4
1.0 Nm
Specially designed for applications with fast
changing electrical load
AlN
Voltage Proof
max. Current
Thermal EMF
Operating Temperature Range
Resistor Material
Substrate
Housing
Connector Material
Terminals
Max. Torque
Notes
Ordering Information
Part Number - Resistance - Contact - Tolerance - TCR
USR 4-3825H 10Ohms D 0.5% 3ppm
Document Number: 64223
Revision: 20-09-10
For technical questions, contact:
powertron@vishaypg.com
www.powertron.de
1
USR UNR 4-3425 3825 4020
Powertron
SPECIFICATIONS
(continued)
Temperature Coefficient
1500
1000
-5ppm/K
+5ppm/K
500
DR/R
(ppm)
0
+4,4 ppm/K
Nominal Spread
±2.3ppm/K
Nominal
DR/R
Nominal Spread
±2.3ppm/K
-500
-1000
-1500
-50
-25
0
50
25
Temperature (°C)
75
100
125
Derating
Power (% from
nominal power)
120
100
80
60
40
20
0
25
50
85
100
115
130
145
155
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 :
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)
Dimensions
USR 4-3425 / UNR 4-3425
tol.
(±mm)
2.0
0.3
0.2
0.2
0.1
0.2
0.1
0.1
0.2
0.2
0.1
0.1
0.2
tol.
(±inches)
0.079
0.012
0.008
0.008
0.004
0.008
0.004
0.004
0.008
0.008
0.004
0.004
0.008
Dimension
A
B
C
D
E
F
G
H
I
J
K
L
M
mm
50.00
34.00
25.00
10.00
5.00
17.80
Ø3.50
Ø0.8
27.50
17.50
2.00
5.50
3.00
inches
1.97
1.34
0.98
0.39
0.20
0.70
Ø0.14
Ø0.031
1.08
0.69
0.08
0.22
0.12
www.powertron.de
2
For technical questions, contact:
powertron@vishaypg.com
Document Number: 64223
Revision: 20-09-10
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
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properties described in the product specification is suitable for use in a particular application.
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Document No.: 63999
Revision: 27-Apr-11
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