Historically, a resettable PPTC (polymeric positive temperature coefficient) device's functionality was restricted when a system's PCB was encapsulated to protect it from water, chemicals, oil, grease, dirt and other potentially damaging elements. To overcome this design issue, the new LVB125 device utilizes an innovative box-like package that reduces the pressure on the device when thermal expansion of the potting material occurs. By providing resettable circuit protection for these applications, the LVB125 device helps improve product reliability and reduce field service and warranty issues.
Unlike a single-use current fuse, the resettable LVB125 PolySwitch device can help protect against conditions where faults may cause a rise in temperature with only a slight increase in current draw. When installed on the primary side of the circuit, in proximity to potential heat-generating components such as magnetics, FETs, or power resistors, the LVB125 device can help protect against damage caused by both overcurrent and overtemperature conditions with a single component.
The package design of the LVB125 device allows it to operate over a wide temperature range (-40°C to 85°C) typical of extreme environments. The thermally active, flame-resistant device meets UL-94 V0 standards, provides excellent dielectric withstand characteristics and can be easily modified to suit customer requirements, such as package color coding. The package can also be reflowed on the PCB with plastic posts that easily affix the device to the PCB during the reflow process.
"By making it possible to use a resettable circuit protection device in potted applications, our new LVB125 device solves what was previously a vexing design issue," said Jasmine Hu, Product Manager. "This device expands our PolySwitch product line by providing robust overcurrent and overtemperature protection for electronic devices and systems that are exposed to harsh environments."
The LVB125 device is rated at 240VAC, permitting maximum voltages of up to 265VAC, and offers a 1.25A hold current. All PolySwitch LVR devices are Pb-free and halogen-free, RoHS compliant and are compatible with high-volume assembly procedures.