USR UNR 2-T220 / T220B / T221
USS UNS 2-T220
Precision Foil Resistors
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•
•
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Resistances from 0.5Ohm to 150kOhms
Power Rating to 10Watt
Resistance Tolerances to ±0.01%
TCR to ±3ppm/K
Load Stability to 0.01%
TO-220 Housing
Convenient SMD D2Pak Available
SPECIFICATIONS
Type
Resistance Range
Power rating
free air 70°C (R<50R0)
free air 70°C (R>50R0)
with heatsink (R<50R0)
with heatsink (R>50R0)
Thermal Resistance Rthj-c
R<50R0
R>50R0
Tolerances
from 0.5 Ohms
from 10.0 Ohms
from 25.0 Ohms
from 50.0 Ohms
Stability
Shelf Life Stability
Temperature Coefficient
Voltage Proof
Thermal EMF
Operating Temperature Range
Resistor Material
Substrate
Housing
Connector Material
Terminals
Soldering Temperature
Max. Torque
Notes
Al
2
O
3
Epoxy + Cu heatsink nickel plated
Cu tinned
2
210°C <30 seconds
other versions upon request
1.0 Nm
Specially designed for applications with fast
changing electrical load
USR / USS
0.5 Ohms to 150 kOhms
1.5W
1.0W
10W
6W
10.8 K/W
18.8 K/W
0.1% / 0.25% / 0.5% / 1%
0.05% / 0.1% / 0.25% / 0.5% / 1%
0.02% / 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)
1 kVDC
< 0.1µV/K
-55 to 155°C
NiCr-Foil
UNR /UNS
0.5 Ohms to 5 kOhms
1.5W
1.0W
15W
10W
6.8 K/W
10.8 K/W
AlN
Ordering Information
Part Description: Part Type - Resistance - Contact - Tolerance - TCR
Example: UNR 2-T220B 5.7kOhms C 0.5% 3ppm
Riedon Inc.
10/13
300 Cypress Avenue
Alhambra CA 91801
www.riedon.com
(626) 284-9901
(626) 284-1704
USR UNR
2-T220 / T220B / T221
USS UNS
2-T220
Precision Foil Resistors
SPECIFICATIONS
(continued)
Temperature Coefficient
800
600
+5ppm/K
-5ppm/K
∆R/R (ppm)
400
200
0
-200
Nominal ∆R/R
Nominal Spread
±2.3ppm/K
-400
-600
-800
-50
-25
0
25
50
75
100
125
Nominal Spread
±2.3ppm/K
Temperature (°C)
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
θH
= T
MAX
- ( P x R
θR
) - T
A
P
Where:
R
θH
= Thermal Resistance of Heatsink ( K/W )
R
θR
= 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
USS 2-T220 / UNS 2-T220
Dimension
A
B
C
D
E
F
G
H
I
J
K
mm
12.70
10.16
0.76
5.08
4.00
1.20
14.60
15.00
17.33
0.40
1.85
tol.
(±mm)
0.2
0.2
0.1
0.1
0.1
0.1
0.2
0.2
0.2
0.1
0.1
inches
0.50
0.40
0.03
0.20
0.16
0.05
0.57
0.59
0.68
0.02
0.07
tol.
(±inches)
0.008
0.008
0.004
0.004
0.004
0.004
0.008
0.008
0.008
0.004
0.004
Dimension
A
B
C
D
E
F
mm
12.10
11.16
18.33
5.08
1.76
3.20
inches
0.476
0.439
0.722
0.200
0.069
0.126
Riedon Inc.
10/13
300 Cypress Avenue
Alhambra CA 91801
www.riedon.com
(626) 284-9901
(626) 284-1704
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