Sales and Corporate Office
1717 Chicago Avenue
Riverside, California 92507-2364
Phone: (951) 788-1700
Fax: (951) 369-1151
Applications Engineering
17271 North Umpqua Hwy.
Roseburg, Oregon 97470-9422
Phone: (541) 496-0700
Fax: (541) 496-0408
e-mail: caddock@caddock.com • web: www.caddock.com
For Caddock Distributors listed by country see caddock.com/contact/dist.html
© 2004 Caddock Electronics, Inc.
CAD KDOC
Type USF Ultra-Stable Low TC Film Resistors
Zero Nominal TC — Maximum Absolute TC to 2 ppm/°C, -40°C to +85°C ref. to +25°C
Absolute Tol. to ±0.01%, Resistance Range 50 Ohm to 25 Megohm, Voltage Ratings up to 2500 Volts
Type USF 300 Series Ultra-Stable Resistors
• ZERO Nominal TC — Max. Absolute TC: 5 ppm/°C,
-40°C to +85°C, referenced to +25°C
Type USF 200 Series Ultra-Stable Resistors
• Constructed with two selected USF 300 Series
Resistors bonded back to back to achieve
outstanding low Absolute Temperature Coefficient
performance. The resistors are to be connected in
parallel on the circuit board.
• ZERO Nominal TC — Max. Absolute TC: 2 ppm/°C,
-40°C to +85°C, referenced to +25°C
The USF Ultra-Stable Low TC Ultra-Precision Film Resistors were
developed to meet the requirements for increasing performance for
resistors in high performance analog electronics. Utilizing Caddock
proprietary resistance film systems, the Type USF resistors provide
the Lowest TC with the Widest Resistance Range and the Highest
Voltage Ratings available in the industry.
• Resistance Range 50 ohm to 25 Megohm.
• Temperature Coefficient -40°C to +85°C, referenced to +25°C
200 Series — ZERO Nominal TC — Maximum Absolute TC 2 ppm/°C
300 Series — ZERO Nominal TC — Maximum Absolute TC 5 ppm/°C
• Tolerance: ±0.01% or ±0.10%.
• Specific standard resistance values are available that are most
commonly required in high accuracy analog design. These values
were selected and optimized for produceability and performance.
• 300 Series “matched pairs” are available with ratio TC as tight as
0.5 ppm/°C. Contact Applications Engineering.
• Ceramic package provides cool operation.
Type USF Ultra-Stable Resistors are offered in standard resistance values
that are most commonly used in precision analog design. These standard
resistance values can be used in precise amplifier gain setting, precise
resistor bridge circuits, precise transducer sense circuits, and precise
voltage dividers with up to 2500 volt input voltage.
Extremely Low Power Coefficient (Wattage Coefficient): Type USF
resistors are constructed with an aluminum oxide ceramic sandwich
which provides great thermal conductivity. The ceramic sandwich
package very effectively minimizes the power coefficient drift. Power
coefficient is the resistance drift due to temperature rise in the element
caused by the power (wattage) dissipation in the resistor where the self-
heating temperature rise of the resistor element results in TC drift (temp.
rise in °C, times the temperature coefficient of the resistor). In the USF
package, heat is pulled away from the resistance material efficiently by
this ceramic sandwich package construction. Plastic molded Low TC foil
resistors cannot provide this outstanding benefit since the plastic impedes
the flow of heat, causing greater temperature rise at the resistor element
and greater self-heating related resistance drift due to power dissipation.
The USF 200 Series resistors provide a new level of performance with
near ZERO TC, very low power coefficient, wide resistance range, and
higher voltage ratings than is offered by other resistor technologies.
Wattage
@ +85°C
Maximum
Continuous
Oper. Voltage
Temperature
Coefficient
USF340
0.33
0.75
A D
Dimensions inches (mm)
5
ppm/°C
Model Number
300
1,400
USF370
USF371
0.75
2,500
Min.
Max.
Resistance
20 Meg
50 Ω
10 Meg
990 K
25 Meg
19.8 Meg
USF270
2 ppm/°C
USF271
2 ppm/°C
USF240
2 ppm/°C
.600 ±.020
(15.24 ±.51)
1,400
2,500
300
0.75
0.75
0.33
.375 ±.020
(9.53 ±.51)
.500 ±.020
(12.70 ±.51)
C
.500 ±.020
(12.70 ±.51)
.500 ±.020
(12.70 ±.51)
.500 ±.020
(12.70 ±.51)
B
.750 ±.020
(19.05 ±.51)
1.500 ±.020
(38.10 ±.51)
1.500 ±.020
(38.10 ±.51)
1.500 ±.020
(38.10 ±.51)
1.500 ±.020
(38.10 ±.51)
Fig.
2
2
2
1
1
1
10 Meg
50 Ω
5 Meg
990 K
10 Meg
9.9 Meg
.375 ±.020
(9.53 ±.51)
.750 ±.020
(19.05 ±.51)
1.350 ±.020
(34.29 ±.51)
.425 Max.
(10.8 Max.)
.550 Max.
(13.97 Max.)
1.350 ±.020
(34.29 ±.51)
.550 Max.
(13.97 Max.)
.600 ±.020
(15.24 ±.51)
1.350 ±.020
(34.29 ±.51)
1.350 ±.020
(34.29 ±.51)
.395 Max.
(
10.03 Max.
)
.520 Max.
(
13.21 Max.
)
.520 Max.
(
13.21 Max.
)
5
ppm/°C
5
ppm/°C
200 Series and 300 Series
New
Page 1 of 2
28_IL134.1004
Sales and Corporate Office
1717 Chicago Avenue
Riverside, California 92507-2364
Phone: (951) 788-1700
Fax: (951) 369-1151
Applications Engineering
17271 North Umpqua Hwy.
Roseburg, Oregon 97470-9422
Phone: (541) 496-0700
Fax: (541) 496-0408
e-mail: caddock@caddock.com • web: www.caddock.com
For Caddock Distributors listed by country see caddock.com/contact/dist.html
© 2004 Caddock Electronics, Inc.
CAD KDOC
A
B
.50 ±.125
(12.70 ±3.18)
.032 DIA.
(.81 DIA.)
.200 ±.020
(5.08 ±.51)
C
(seated height)
D
.160 ±.030
(4.06 ±.76)
USF 200 Series Circuit Board Connection Note: The Type USF 200
Series Resistor must have the two “bonded” resistors in the package connected
in parallel on the circuit board as shown. This parallel connection of the two
resistors achieves the specified resistance with the specified performance.
Circuit Board Trace
Circuit Board Trace
Front View
Side View
Top View
Dimensions in inches
and (millimeters)
Fig. 1
USF 200 Series
CADDOCK
USF240
0418
.50 ±.125
(12.70 ±3.18)
.032 DIA.
(.81 DIA.)
.075 ±.020
(1.91 ±.51)
A
B
C
(seated height)
D
Side View
Front View
Fig. 2
USF 300 Series
Dimensions in inches
and (millimeters)
CADDOCK
USF340
0412
Ordering Information USF300 Series:
Ordering Information USF200 Series:
USF370
- 990K - 0.10% - 5 ppm/°C
Model Number
Resistor Value
Tolerance
(0.01% or 0.10%)
USF240
- 10.0 Meg - 0.01% - 2 ppm/°C
Model Number
Resistor Value
Tolerance
(0.01% or 0.10%)
50.0 Ω
100 Ω
200 Ω
250 Ω
350 Ω
500 Ω
900 Ω
1.00 K
2.00 K
2.50 K
5.00 K
9.00 K
10.0 K
20.0 K
25.0 K
50.0 K
USF240 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 2ppm/°C
90.0 K
99.0 K
100 K
200 K
USF270 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 2ppm/°C
Standard Resistance Values:
Specifications:
Resistance Tolerance: ±0.01% or ±0.10 measured at +23°C ±2°C.
Absolute Temperature Coefficient: TC referenced to +25°C,
ΔR taken at -40°C and +85°C.
Load Life Stability: 2,000 hours at +85°C at rated voltage, not to
exceed rated power, ΔR (+0.015 ±0.015)% max.
10,000 hours at +85°C at rated voltage, not to exceed rated
power, ΔR (+0.030 ±0.030)% max.
Thermal Shock: Mil-Std-202 Method 107 condition A, except min.
temp. is -40°C, ΔR ±0.01% maximum.
Voltage Coefficient: USF270 at 5 Meg, and USF271, USF370,
USF371 at resistances of 9 Meg or greater, 0.02 ppm/volt
maximum.
Shelf Life Stability: Typical +(20ppm ±20ppm)/yr. after 1 year.
Extended shelf life (ten years) 10ppm/year maximum.
Operating Temperature: -40°C to +85°C.
Leadwire: Solder Coated Copper.
Other Low TC Resistor Products from Caddock:
• Type TF Low TC Ultra-Precision Film Resistors (1K to 125Meg)
• Type TN Lab Grade Low TC Precision Film Resistors
• Type TK Low TC Precision Radial-Lead Film Resistors
• Type TG Low TC Precision High Voltage Resistors (up to 30KV)
• T912 and T914 Low TC Ultra-Precision Resistor Networks
• Type USVD Ultra-Stable Voltage Dividers (up to 2500V)
• Type THV Precision High Voltage Dividers (up to 20KV)
250 K
500 K
1.00 Meg
2.00 Meg
2.50 Meg
5.00 Meg
9.90 Meg
9.99 Meg
10.0 Meg
Custom USF 200 Series and 300 Series Resistors:
USF 200 Series and 300 Series Resistors are available, for high
quantity applications, with custom performance:
• In the 200 Series, Absolute TC to as tight as 1ppm/°C is available
for certain resistances.
• Matched Ratio TC to as tight as 0.5ppm/°C for equal resistances.
• Matched Ratio TC can be provided in the 200 Series style “bonded”
Resistor pairs.
990 K
USF271 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 2ppm/°C
9.90 Meg
1.00 Meg 2.00 Meg
9.99 Meg 10.0 Meg
USF340 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 5ppm/°C
USF370 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 5ppm/°C
USF371 Standard Resistance Values:
Absolute Tolerance: ±0.01% or ±0.10%, Absolute TC: 5ppm/°C
50.0 Ω
100 Ω
200 Ω
350 Ω
400 Ω
500 Ω
700 Ω
1.00 K
1.80 K
2.00 K
4.00 K
5.00 K
10.0 K
18.0 K
20.0 K
40.0 K
50.0 K
90.0 K
99.0 K
100 K
180 K
198 K
200 K
400 K
990 K
1.00 Meg
1.98 Meg
2.00 Meg
19.8 Meg
500 K
990 K
999 K
1.00 Meg
2.00 Meg
4.00 Meg
5.00 Meg
9.90 Meg
9.99 Meg
10.0 Meg
19.8 Meg
19.98 Meg
20.0 Meg
4.00 Meg
5.00 Meg
9.90 Meg
9.99 Meg
19.98 Meg 20.0 Meg
10.0 Meg
5.00 Meg
25.0 Meg
Type USF Ultra-Stable Low TC Film Resistors
200 Series and 300 Series
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28_IL134.1004
