CS Series Current Sensing Chip Resistors

What are the CS Series Current Sensing Chip Resistors?

The CS Series is a family of thick film chip resistors optimised for current sensing duty, distinguished from general-purpose thick film resistors by their low resistance values, higher rated currents, and construction choices that maximise power dissipation within each package size. The resistive element is a thick film material deposited on a high-purity alumina ceramic substrate, which provides both the electrical isolation and the thermal conductivity needed to dissipate the power generated when a current sense resistor carries load current continuously.

The key construction feature of the larger packages in the CS Series is the use of long-side terminations — also known as wide or reverse-geometry terminations — on the CS25 (1225), CS37 (3720), CS75 (7520), and CS62 (0612) packages. In a conventional chip resistor the solder joints are at the two short ends of the body, and the current path runs the length of the component. In a long-side termination design the electrodes run along the two long edges, shortening the current path through the resistive element and dramatically reducing the thermal resistance between the element and the PCB copper. This allows the 1225 package to achieve a 3W rating in what is physically a 1W-sized footprint when measured by body length, by spreading heat into a much larger PCB contact area. The same principle allows the 7520 to carry up to 44.7A continuously within a 2W power budget.

Across the standard geometry packages — 0201 through 2512 — the CS Series covers the resistance range from 1mΩ upward, with TCR values that reflect the resistance zone: at lower resistance values within a given package (typically 1mΩ to 50mΩ), TCR is ±400ppm/°C to ±1000ppm/°C, while at higher resistance values (100mΩ to 8000mΩ) TCR improves to ±100ppm/°C to ±300ppm/°C. This TCR progression is characteristic of thick film technology and should be taken into account when specifying the CS Series for applications where current measurement accuracy over a wide temperature range is a primary requirement. For applications where TCR must be below ±100ppm/°C at low resistance values, the metal alloy LR and MR series or metal foil MFF and MFR series offer superior performance; the CS Series positions itself as the cost-effective, broadly available thick film solution for general-purpose current sensing where moderate TCR is acceptable.

The alumina substrate and flame-retardant overcoat construction are compatible with standard reflow soldering profiles at 260°C. The MSL Level 1 classification means no baking or special dry storage is required before assembly, simplifying handling in production environments. The extensive case size selection from 0201 to 7520 provides a single product family that can be specified at the smallest available SMD footprint for space-constrained designs and scaled up to the largest footprint where power dissipation or current-handling requirements demand it.

Model: CS
Resistor type: Current sensing
Description: Chip
Power Rating: 1/20W~3W
Resistance (Ω): 1m~8000m
Tolerance (%): ±1, ±2, ±5
TCR (ppm/C): 100, 1000

Model: CSTN
Resistor type: Current sensing
Description: Chip
Power Rating: 1/16W~3W
Resistance (Ω): 50m~1000m
Tolerance (%): ±0.5, ±1
TCR (ppm/C): 50, 100, 200

Model: RS
Resistor type: Current sensing
Description: Thick film chip
Power Rating: 1/16W~2W
Resistance (Ω): 10m~976m
Tolerance (%): ±1, ±5
TCR (ppm/C): 200, 1500

Model: RTX
Resistor type: Current Sensing
Description: Chip
Power Rating: 1/8W~2W
Resistance (Ω): 50m~1000m
Tolerance (%): ±0.5, ±1, ±2, ±5
TCR (ppm/C): 75-300