Ceramic current sense resistors offer values down to 2.5Ω
Stackpole's CSRF Series utilises foil on ceramic technology to achieve very low values in small chip sizes. The 0.25W rated CSRF0402 - HP, for example, is available in resistance values from 20Ω down to 2.5Ω. TCR ranges from ±400ppm to ±200ppm are possible depending on resistance value with tolerances as low as one percent.
This combination of small size and low value make the CSRF0402 - HP a popular choice for a wide range of portable consumer electronics for power control and battery monitoring.
Pricing for the CSRF0402-HP depends on resistance value, and tolerance and ranges from $0.205 to $0.23 each in full package quantities.