Automotive Circuit Protection TDK’s portfolio of automotive circuit protection devices includes AVR series chip varistors for voltage protection and NTC thermistors for temperature protection. AVR varistors protect against electrostatic discharge (ESD), voltage surges in power supplies from lightning, and systems for power generation and distribution. These products are also used in the highly-sensitive electronics in vehicles, household appliances, PCs, and notebook computers. NTC thermistors protect internal circuits or devices from overheating by acting as temperature sensors in monitoring systems. TDK has reduced the size of NTC products by applying the same multilayer technology developed for multilayer ceramic chip capacitors (MLCCs).