Current Sense Resistor | Making sense of the options

8th March 2018

What can DMTL offer?

At DMTL we offer Current Sense Resistors / Shunt Resistors, from various manufacturers; including First Ohm, HTR, Nikkohm, Riedon, State of the Art & Viking. With each manufacturer specialising in one or more of the resistive technologies outlined above.

This allows DMTL not only to compete against well know manufacturers of current sense or shunt resistors i.e. Arcol, Bourns, Caddock, IRC, Isabellenhuette, KOA, Ohmite, Panasonic, Susumu, Welwyn, Yageo, Vishay, etc... but also , to work with engineers to fulfill specific user solutions, using core electrical and application information and generating new design solutions.

Below we look at some product highlights from DMTL’s manufacturers, for the various technologies outlined.

Current Sense Resistor Options

With a recent explosion in the need to accurately measure voltage in circuits, the Current Sense Resistor , also referred to as a Shunt Resistor, has steadily been increasing in technology options. For example; Thick Film, Thin Film, Electron Beam Welded (EBM), Metal Strip, Metal Foil & Wirewound variants.

These different Current Sense / Shunt Resistor technologies are available in SMD, MELF, Axial, Radial & Chassis Mount packages, with options for 2 (two) terminal or 4 (four) terminal “Kelvin” connections.

Why Choose a Current Sense Resistor?

Due to Ohm’s law, a requirement exists for a low ohmic value resistor (typically but not always, measurement of currents in the picoamp range).

Application requirements differ with specific user demands in terms of; the current (or power) rating and the required accuracy which will also need to take account of changes from the initial ohmic value, due to a combination of factors including, absolute tolerance, TCR, self-heating, EMF (thermocouple effect), pulse / surge effects and the long-term stability of the resistor material itself.

Highlighted Products

Thick Film - Current Sense Chip Resistor – CS Series

Viking Tech - CS Series Datasheet

Available in industry standard case-sizes (and reverse terminations) the CS Series of current sense / shunt resistors are manufactured utilising highly reliable thick film technology. With values as low as 1mR, power ratings up to 3W, current to 44.7A, TCR as low as 100ppm/DegC and 1% tolerance. This is a low-cost, Current Sense Resistor / Shunt Resistor.

Thin Film - Current Sense Chip Resistor – TCS Series

Viking Tech - TCS Series Datasheet

Thin film offers the next level of accuracy for Current Sense Resistors. Available in industry standard case-sizes; the TCS Series of Current Sense / Shunt Resistors, offers values as low as 50mR, power ratings up to 3W, TCR as low as 50ppm/DegC and 0.5% tolerance. The TCS can still be considered as low-cost solution for Current Sense / Shunt Resistor requirements.

Electron Beam Welded - Current Sense SMD Resistor – HRE Series

HTR - HRE Series Datasheet

Electron Beam Welded Current Sense / Shunt Resistors are used in applications requiring a higher power / current rating, whilst also demanding very good overall accuracy. With 4 (four) terminal “Kelvin” connections, values as low as 0.2mR, power ratings up to 10W, current to 160A, TCR as low as 20ppm/DegC and 1% tolerance. Furthermore, the ability to withstand significant pulse / surge demands & excellent overall load-stability (from the use of Manganin resistive alloy), offers a solution which can meet harsh application demands.

Metal Strip – SMD Resistor – HTE Series.

HTR - HTE Series Datasheet

Part of the Electron Beam Welded (EBM) family of technology, Metal Strip is a technology which encompasses many of the benefits detailed previously including pulse / surge withstanding, but available in convenient industry case-sizes. Values as low as 0.3mR, power ratings up to 6W, TCR’s as low as 50ppm/DegC and 0.5% tolerance. Satisfying demanding applications, while keeping a close eye on cost, is a key selection criteria for the HTE Series.

Metal Foil – SMD Resistor – CSM Series.

VIking Tech - CSM Series Datasheet

Like Metal Strip, but utilising a foil resistive element. Metal Foil is for applications which require multiple performance criteria. Values as low as 10mR, power ratings up to 1W, TCR’s as low as 50ppm/DegC and 0.5% tolerance.

Wirewound – SMD Resistor – SC-2 Series

Riedon - SC-2 Series Datasheet

For users looking for the ultimate in measurement accuracy; Wirewound Current Sense / Shunt Resistors are a technology frequently overlooked, but offering values as low as 0.5mR, power ratings up to 2W, current to 25A, TCR’s as low as 5ppm/DegC and 0.005% tolerance. Wirewound can sometimes makes which was first thought impossible, possible!