Low Rho SMD Series - PolySwitch packaged PPTC for general electronics overcurrent protection

Low Rho SMD
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Information furnished is believed to be accurate and reliable. However, users should independently evaluate the suitability of and test each product selected for their own applications. Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, military, aerospace, medical, life-saving, life-sustaining or nuclear facility applications, devices intended for surgical implant into the body, or any other application in which the failure or lack of desired operation of the product may result in personal injury, death, or property damage) other than those expressly set forth in applicable Littelfuse product documentation. Warranties granted by Littelfuse shall be deemed void for products used for any purpose not expressly set forth in applicable Littelfuse documentation. Littelfuse shall not be liable for any claims or damages arising out of products used in applications not expressly intended by Littelfuse as set forth in applicable Littelfuse documentation. The sale and use of Littelfuse products is subject to Littelfuse Terms and Conditions of Sale, unless otherwise agreed by Littelfuse. "Littelfuse" includes Littelfuse, Inc., and all of its affiliate entities.

PolySwitch® low resistivity SMD (surface-mount device) is versatile device well suited for general applications which have space-constrained, low power dissipation and high environmental reliability requirements.

The devices can help provide both overcurrent and overtemperature protection for battery pack PCMs (protection circuit modules), circuit PCBA and signal/power I/O interface. The resettable feature ensures the device will “Trip” and protect the application during the faults and yet regain the functions once the error is removed.

The low resistivity SMD series comprises 20 devices. In the model number descriptions, the “micro” prefix refers to the 1210 form factor and the “nano” prefix refers to the 1206 form factor.


  • Current ratings from 1.75 to 6.0A
  • Maximum electrical rating: Voltage 6VDC and short circuit current 50A
  • RoHS compliant
  • Halogen free (refers to: Br<=900ppm, Cl<=900ppm, Br+Cl<=1500ppm)
  • Agency recognition: UL, CSA, TÜV


  • Exclusive and robust “Packaged-Chip” design to withstand thermal soldering and stressed molding process
  • Available in compact 1206 and 1210 sizes to accommodate industrial standard footprint and save the board space
  • Ultra-low internal resistance Reset automatically
  • Fast time-to -trip


  • Mobile and smart phones
  • Wearable devices
  • Portable game console
  • VR/AR head mount display (HMD)
  • Tablets and eBook
  • Portable printed and projector
  • Li-ion battery Powered Mobile Devices
  • USB Connection Ports

Access specifications, certifications, check availability and order parts below

Catalog #IHold (A)ITRIP
Max Volts
Trip Time
microSMD190LR-21.94.965010.0060.0219.541210Product SpecificationCheckOrder
microSMD200LR-22565010.0060.0219.541210Product SpecificationCheckOrder
microSMD250LR-A-22.55.265010.0050.0189.551210Product SpecificationCheckOrder
microSMD350LR-23.5965010.00250.011101210Product SpecificationCheck
microSMD350LR-D-23.5965010.00250.0119.5101210Product SpecificationCheckOrder
microSMD380LR-23.8965010.00250.0099.5101210Product SpecificationCheckOrder
microSMD400LR-24965010.00250.0099.5101210Product SpecificationCheckOrder
microSMD450LR-24.5955010.00250.0119.5101210Product SpecificationCheckOrder
microSMD500LR-251065010.0020.0072521210Product SpecificationCheckOrder
microSMD550LR-25.51155010.0020.0062521210Product SpecificationCheckOrder
microSMD600LR-261265010.0020.0062521210Product SpecificationCheckOrder
nanoSMD175LR-21.75565010.0080.0349.511206Product SpecificationCheckOrder
nanoSMD200LR-22665010.0060.0249.531206Product SpecificationCheckOrder
nanoSMD270LR-22.76.365010.0050.018851206Product SpecificationCheckOrder
nanoSMD350LR-23.56.365010.0040.018851206Product SpecificationCheckOrder
nanoSMD380LR-23.8865010.0040.0149.5101206Product SpecificationCheckOrder
nanoSMD400LR-24865010.0040.012021206Product SpecificationCheckOrder
nanoSMD450LR-24.5965010.0020.0082521206Product SpecificationCheckOrder
nanoSMD500LR-251065010.0020.00821206Product SpecificationCheck
nanoSMD500LR-D-251065010.0020.0082521206Product SpecificationCheckOrder
nanoSMD550LR-25.51165010.0020.00752521206Product SpecificationCheckOrder
nanoSMD600LR-261265010.0020.0072521206Product SpecificationCheckOrder