Interfacing the Coto Technology RedRock RR110

Posted on Thursday, May 4th, 2017

Interfacing the Coto Technology RR110 to an ADC using a low power analog interface circuit.

Background Portable medical devices, such as personal insulin pumps, have gotten smaller with time, allowing them to be conveniently carried by the user. This convenience has been made possible by intelligently and accurately dispensing product when active, and ensuring very low quiescent current when not active. Sensing technologies used to monitor the position of the plunger, therefore, need to be accurate in order to ensure the correct dosage, while being extremely frugal on power demand in order to fit within the operation profile of the device with the chosen battery. The RR110 analog sensor – from Coto Technology’s RedRock Series sensor product line – has high sensitivity and operates with ultra-low current, making it ideally suited for these applications. The RR110 is a two-terminal, passive analog magnetic sensor based on the Tunneling Magnetoresistance (TMR) principle. Resistance of the Magnetic Tunneling Junction (MTJ) changes from approximately 65kΩ with zero magnetic field, to approximately 40kΩ in the presence of ~10mT magnetic field and can be used reliably with a current as little as 1mA to measure the resistance change as a change in voltage. 

See the RR110 specification

Please see the complete Application Note

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