1. Product Overview: Caddock USF Ultra-Stable Low TC Film Resistors

️· Type: These are precision film resistors designed for stability and low temperature coefficient (TC).
️· Series: Two main series are featured:
- USF200 Series: Emphasizes tighter TC (2 ppm/°C) and potentially even tighter (1 ppm/°C for some values)
- USF300 Series: TC of 5 ppm/°C
️· Target Applications: High-precision circuits where stability is critical.
️· Customization: Caddock offers custom performance, including tighter TC and matched resistor pairs (bonded).

2. Specifications (Key Performance Metrics)

️· 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.
- USF200: 2 ppm/°C (can be tighter)
- USF300: 5 ppm/°C
️· Load Life Stability:
- 2,000 hours at +85°C: ΔR within limits.
- 10,000 hours at +85°C: ΔR within stricter limits.
️· Thermal Shock: Meets MIL-STD-202, with a minimum temperature of -40°C.
️· Voltage Coefficient: For specific resistance values (e.g., 5 Meg for USF270, 9 Meg or greater for USF271, USF370, USF371).
️· Shelf Life Stability: Typically +(20ppm ±20ppm)/yr; after 1 year can be as low as 10ppm/year.
️· Operating Temperature: -40°C to +85°C
️· Leadwire: Solder-coated copper.

3. Standard Resistance Values (Listed for Each Sub-Series)

️· USF240: 50.0 Ω, 100 Ω, 200 Ω, 350 Ω, 2.00 K, 10.0 K, 350Ω, 18.0K, 20.0 K, 25.0 K
️· USF270: 10.0 K, 18.0 K, 20.0 K, 25.0 K, 50.0 K
️· USF271: 990 K, 1.00 Meg, 2.00 Meg
️· USF340: Similar range to earlier series, with a good representation of common resistor values.
️· USF370: Broad selection, again including common values.
️· USF371: Focuses on higher resistance values.

4. Ordering Information (Structure)

The ordering information follows this pattern:

️· `USF[series number][4 digits]`
️· `Resistor Value`
️· `Tolerance (0.01% or 0.10%)`
️· `TC (ppm/°C)`

Example: `USF270 - 1.00 Meg - 0.01% - 2 ppm/°C`

5. Other Caddock Low TC Products

Caddock offers a variety of related products for different needs:

️· Type TF
️· Type TN
️· Type TK
️· Type TG
️· T912 and T914
️· Type USVD
️· Type THV

6. Contact Information

️· Sales/Corporate Office: Riverside, CA (Phone and Fax)
️· Applications Engineering: Roseburg, OR (Phone and Fax)
️· Website: [www.caddock.com](http://www.caddock.com)
️· Email: caddock@caddock.com