Power

Mini-breakers boast higher current capabilities

28th April 2025
Mick Elliott
0

Bourns has announced its latest NX series miniature resettable thermal cutoff (TCO) device series, also known as mini-breakers, that are designed to control abnormal, excessive current virtually instantaneously, up to rated limits.

They are in stock at authorised  distributor Anglia Components.

Bourns Mini-breakers are a combination of two common circuit protection technologies: a PTC and a bimetal switch, providing several advantages over either technology on its own. The skills developed by Bourns over 75 years in precision metal stamping, plastic injection molding and high-end assembly turn these ubiquitous technologies into a market leading circuit protection solution.

The figure provides a simple schematic of how the NX series mini-breaker is constructed. The two terminals (arm terminal and base terminal) are connected in a normally closed position to allow current to flow through the device. Naturally, the contact point between both terminals provides a critical function and a testament to the high precision of the Bourns Mini-breaker is that the contact resistance is as low as 1 mΩ (max.) in some model families.

The Model NX Series offers higher current-carrying capabilities combined with a very low-profile package at a height of just 0.94 mm and body width of 2.8 mm. The compact design makes it an ideal overtemperature and overcurrent protection solution for lithium polymer and prismatic cells in high energy density, smaller batteries such as next-generation notebook PC and tablet battery cells, as well as other handheld and wearable electronic devices that require compact and reliable protection.

With its higher current capabilities and ultra-small size the Model NX Series enables customers to shrink their product size and still maintain an elevated level of overtemperature protection.

These mini-breakers have the same footprint as the Bourns Model NR series yet it can carry 40 percent more current. This is due to numerous design advancements used in its construction including the use of new high conductivity electrode materials.

The Model NX Series has current capabilities from 12 A to 20 A at 60 °C and is available with or without welding projections.

Providing design flexibility for a wide range of application environments, these TCO devices are available with four trip temperature options of 77 °C, 82 °C, 85 °C and 90 °C - all of which operate within a ±5 °C tolerance and feature contact resistance of 3 mΩ (max.) / 1.2 mΩ (typ.)

The Model NX Series is also designed with a high-rated corrosion resistant bimetal mechanism that delivers enhanced endurance in humid environments compared to standard TCO devices and is RoHS compliant, halogen free and UL/TÜV recognized.

Anglia is offering customers FREE samples of these miniature resettable thermal cutoff (TCO) devices from Bourns.

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