Abstract:

Power management chips is damaged to varying degrees when they work at the ambient temperature beyond their acceptable range, and the over-temperature protection circuit plays an important role in improving the reliability and robustness of this kind of chip. This study designs a high-precision over-temperature protection circuit with the dual functions of turning off when the temperature is too high and reminding when the temperature is too low. The positive and negative temperature coefficient voltages are used to detect the chip temperature in real time, and then four logic turnover points are obtained by comparing them with different reference voltages at the output end of the band-gap reference circuit. After processing by the high-precision comparator circuit and hysteresis logic circuit, the hysteresis logic signals are output to control the working state of the chip or to remind the low temperature. The design and relevant simulation have been carried out based on 0.18 μm BCD(Bipolar-Complementary Metal Oxied Semiconductor-Double diffused Metal Oxide Semiconductor) process, and the simulation results show that when the power supply voltage ranges from 3.0~ 5.5 V, the maximum offset of the temperature threshold corresponding to the hysteresis logic turnover signal at the output end of the circuit is within 0.3 ℃. The circuit has high precision and can be widely integrated in various power management chips requiring over-temperature protection.

Key words: power management chip, over-temperature protection, high precision, dual functions, band-gap reference, temperature detection, comparator, hysteresis logic