Murata has released a pair of ultra-low power AMR magnetic sensors aimed at switching functions in battery-powered electronics. The MRMS166R and MRMS168R focus on one constraint that keeps coming up in compact systems: standby current.
The MRMS166R and MRMS168R are anisotropic magnetoresistance sensors used as magnetic switches for detecting field presence and controlling system states. In practice, they sit near a magnet and feed a simple signal into system logic, often tied to sleep or wake control in a microcontroller or power management stage.
Designed Around Coin Cell Limits
The MRMS166R runs down to 1.2 V with an average current of 20 nA. That combination lines up with silver oxide coin cells, which typically sit around 1.55 V and don’t leave much margin. For designs that spend most of their life idle, reducing that standby draw has a direct impact on how long the product stays in the field. Murata has adjusted the internal circuitry to hold stable operation at these lower voltages while keeping current down. The result is a device that can support multi-year operation in systems where replacing or recharging a battery isn’t practical.
The MRMS168R shifts slightly in the other direction. It operates from 2.0 to 3.6 V and draws around 80 nA on average, but it can source up to 12 mA at the output. That makes it easier to interface with higher load inputs or drive stages directly.
Magnetic Switching in Sealed Systems
Both parts are intended to replace mechanical switches in applications where contact wear or sealing becomes a problem. There are no moving parts, so there’s no bounce, and the enclosure can remain fully sealed. This is already common in medical patches, capsule devices, and small wearables. A magnetic trigger can bring the system out of sleep or push it back into a low-power state without needing a physical interface. The same approach shows up in IoT nodes such as door sensors and smart locks, where reliability and low standby power tend to sit above switching speed in the priority list.
Small Package, Simple Integration
The package size comes in at 1.0 × 1.0 × 0.4 mm, which is small enough to drop into tight layouts without much planning. Placement is usually driven by magnet position rather than routing constraints, so keeping the footprint minimal helps. The MRMS166R supports a 1.2 to 3.6 V supply range and provides up to 1 mA output, which is enough for direct logic interfacing. The MRMS168R extends that output capability significantly, which opens up use in slightly heavier load conditions.
Standby Current in Battery-Powered Designs
These sensors fall into a category where peak performance isn’t the focus, what's important is how little they consume while waiting. In systems that spend most of their time inactive, the difference between tens of nanoamps and a few microamps adds up quickly. Over months or years, that gap becomes the difference between a battery that lasts and one that doesn’t.
Learn more and read the original announcement at www.murata.com
Technology Overview
MRMS166R and MRMS168R are anisotropic magnetoresistance sensors used for magnetic field detection and contactless switching. They operate from 1.2 to 3.6 V and 2.0 to 3.6 V respectively, with average current consumption as low as 20 nA and a 1.0 × 1.0 × 0.4 mm package.
Frequently Asked Questions
Where would these AMR sensors typically sit in a system?
They are placed near a magnet and connected to system logic to control state changes such as sleep and wake transitions.
Are these sensors suitable for coin cell-powered designs?
The MRMS166R supports operation down to 1.2 V with very low current consumption, making it suitable for coin cell applications.
What is the difference between MRMS166R and MRMS168R?
The MRMS166R prioritizes ultra-low current consumption, while the MRMS168R offers higher output drive capability with increased current draw.
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