TCO devices protect high-energy-density batteries

Bourns, Inc. has announced a new miniature resettable thermal cutoff (TCO) device series that controls abnormal, excessive current up to rated limits instantaneously. The Model NX Series of TCO devices, also called mini-breakers, combines higher current-carrying capabilities with a very low-profile height of 0.94 mm and body width of 2.8-mm.

(Source: Bourns, Inc.)

Bourns said these features make the TCO devices well-suited as an overtemperature and overcurrent protection solution for lithium-polymer and prismatic cells in smaller high-energy-density batteries. These include next-generation notebook PC and tablet battery cells, and  handheld and wearable electronics.

The Model NX mini-breakers feature the same footprint as the previous Model NR series yet carry 40 percent more current. This is due to design enhancements, including the use of new high-conductivity electrode materials.

Current capabilities span 12 A to 20 A at 60°C, available with or without welding projections. The devices are available with four trip temperature options of 77°C, 82°C, 85°C and 90°C, all operating within a ±5°C tolerance.

The series also has a high-rated corrosion resistant bimetal mechanism for enhanced endurance in humid environments, compared to standard TCO devices. The TCO devices reset when the ambient temperature drops by 10°C below the minimum trip temperature, and when power to the TCO device has been cycled (off/on).

The Model NX Series is currently available. The TCO devices are RoHS compliant, halogen free and UL/TÜV recognized.