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

K

DOC

Type USF Ultra-Stable Low TC Film Resistors

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.

200 Series —

ZERO Nominal TC — Maximum Absolute TC 2 ppm/°C

300 Series —

ZERO Nominal TC — Maximum Absolute TC 5 ppm/°C

commonly required in high accuracy analog design. These values

were selected and optimized for produceability and performance.

0.5 ppm/°C. Contact Applications Engineering.

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.

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

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