Stable Inductor Increases Current-Sense Accuracy

Mar 26, 2008 4:01 PM

From TT electronics’ BI Technologies division, a constant DCR surface-mount power inductor maintains a dc resistance with a shift of only ±2% at room temperature and 7% over a 100°C temperature range. This level of the stability enhances measurement accuracy when the HM69S series inductor is used to perform current sensing, potentially eliminating the need for thermal compensation of inductor resistance.

Device type: power inductor
Construction: Ferrite core with unique resistive alloy inductor that combines copper and nickel
Inductance range: 90 nH to 200 nH
Max dc current rating: Ranges from 25 A for 200 nH to 75 A for 90 nH
DCR: 0.880 mΩ typ.
Tolerance of DCR over temperature: ±2%.
Operating frequency range: 100 kHz to 5 MHz
Operating temperature range: -40ºC to +125ºC with a max. temperature rise of +40°C
Packaging: 11.2 mm x 10.3 mm x 5.5 mm (max), surface mount
RoHS compliant? Yes
Target applications: multiphase voltage regulator applications, including powering CPUs
Pricing: from $0.55 to $0.65 each typ. depending on volume and package size.
Availability: available now
Data sheets posted on web? Yes, see www.bitechnologies.com.

Notes: David Smolik, director of product development at BI Technologies comments that copper conductors are typically unstable with a TCR at 3900ppm/°C. “By developing an inductor with a TCR of 700ppm/°C, we are able to provide customers with a much more stable and accurate device, one that does not require thermal compensation for the resistance change of the copper conductor,” says Smolik.