China
Africa
Explore chapters and articles related to this topic
DC-DC Converters
Published in Ali Emadi, Handbook of Automotive Power Electronics and Motor Drives, 2017
Input power polarity reversal protection may be as simple as a diode in series with the input or a more complex scheme utilizing a comparator and pass-switch or crowbar circuit. Overvoltage, undervoltage, and overcurrent protections typically utilize comparator circuitry with sufficient filtering and hysteresis to allow clean trip points and circuits, which are not prone to false or repeated trips due to noise. Thermal protection may come in the form of thermal switches that are mounted next to the power devices on the heat sink. The thermal switch is normally open or closed and has hysteresis. The temperature rating of the thermal switch is selected based on the power device loss calculations, noting the maximum possible case temperature corresponding to the worst-case junction temperature, at the worst-case operating condition, with sufficient safety margin. Typical thermal switch temperature ratings are around 85 to 95ºC. Loss of control power supply is protected against in a variety of ways from dedicated ICs to pull-down resistors on gate driver inputs. Fire protection is protection against catastrophic failure and resulting collateral damage and typically consists of appropriately sized fuses on the input and output of the converter.
Amplifier and Loudspeaker Protection
Published in Douglas Self, Audio Power Amplifier Design, 2013
Another pre-calibrated type of temperature sensor is the thermal switch, which usually operates on the principle of a bistable bimetallic element. These should not be confused with thermal fuses which are once-only components that open the circuit by melting an internal fusible alloy; they are in common use for transformer thermal protection, as they are cheaper than the self-resetting thermal switches. The trouble with thermal fuses is that they are relatively uncommon, and the chance of a blown thermal fuse being replaced with the correct component in the field is not high.
Reliability issues of lead-free solder joints in electronic devices
Published in Science and Technology of Advanced Materials, 2019
Nan Jiang, Liang Zhang, Zhi-Quan Liu, Lei Sun, Wei-Min Long, Peng He, Ming-Yue Xiong, Meng Zhao
The melting temperature of lead-free solder is relatively low, so the variation of temperature load has a significant effect on the properties of the solder joint [11]. Currently, thermal protection is used to maintain the ambient temperature of the electronic device to ensure that the electronic product can operate reliably under extreme conditions. Temperature can change the microstructure and internal stress of the solder joint, which is one of the main factors affecting the solder joint failure. Solder joint failure is the primary cause of electronic component failure, so the influence of temperature on solder joint reliability needs to be further studied. The effect of temperature on solder joint reliability mainly includes aging, thermal cycling, and thermal shock.