WM Series - Surface Mount NTC LL-34 MiniMELF Interchangeable (220°C) ± 1.0°C Accuracy

Series: WM
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Littelfuse products are not designed for, and shall not be used for, any purpose (including, without limitation, automotive, 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.

Littelfuse LL-34 “MiniMELF” style interchangeable glass encapsulated surface mount thermistors are manufactured using super stable NTC chips which are hermetically sealed in a glass package. The result is a device which exhibits excellent long-term reliability and stability even when subjected to severe environmental or thermal conditions. They are well suited for uses where their interchangeability eliminates the necessity for costly individual circuit calibration. Their uniform dimensions make them especially suitable for use with automatic insertion equipment.


  • High temperature capability to +220°C
  • Surface mountable
  • Hermetically sealed glass package
  • Low cost
  • Excellent long-term stability


  • Non-standard resistance values and tolerances
  • Point matched at specified temperatures
  • Tape and reel packaging


  • Interchangeability accuracy of ±1.0°C (0°C to +100°C)
  • Thermal time constant: 8 seconds max
  • Dissipation constant: 2 mW/°C

Access specifications, certifications, check availability and order parts below

Catalog #Resis Ω @ 25°CBeta (K) 0-50°CMin Operating Temp (°C)Max Operating Temp (°C)Engineering DrawingRT TablePartner ECAD ModelsCompare
Part # Part Description RoHS Pb-free RoHS (2015/ 863/EU) Certificate REACH (SVHC’s) Declaration Halogen Free REACH (SVHC’s)
WM103J1B NTC THERMISTOR 10K OHM 1C MELF RoHS No 02/13/2019 PbFree No 02/13/2019
WM104J1A NTC THERMISTOR 100K OHM 1C MELF RoHS No 02/13/2019 PbFree No 02/13/2019
WM153J1A NTC THERMISTOR 15K OHM 1C MELF RoHS No 02/13/2019 PbFree No 02/13/2019
WM203J1A NTC THERMISTOR 20K OHM 1C MELF RoHS No 02/13/2019 PbFree No 02/13/2019
WM503J1A NTC THERMISTOR 50K OHM 1C MELF RoHS No 02/13/2019 PbFree No 02/13/2019
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