一种用于以太网供电的高压检测电路

High voltage detection circuit for power over the ethernet

提出了一种新颖的用于以太网供电的高精度、低温度系数的高压检测电路.该电路使用带隙基准比较器来检测输入电压,而不需要其他比较器和电压基准电路,从而减小了芯片面积和检测时间;同时,使用反馈电路来实现迟滞功能以克服以太网线本身所带有的电阻影响,防止检测电路在检测状态和分级状态之间循环往复变化.该高压检测电路采用0.5μm 65VBCD工艺流片,有效面积为590μm×310μm.测试结果显示,在-40℃到125℃之间,该高压检测电路翻转阈值电压的温度系数为26.5×10-6/℃.20颗芯片的统计测试结果表明,翻转阈值电压为11.9V±0.25V,标准偏差σ为0.138V.

A novel high voltage detection circuit with a high accuracy and low temperature coefficient for Power over the Ethernet （ PoE） application is presented . The proposed detection circuit uses a bandgap comparator to detect the input voltage without an extra comparator and a voltage reference circuit , which reduces the chip area and detection time . In order to overcome the effect of the Ethernet resistor and avoid the circulating change of the detection circuit between the detection state and classification state , the proposed circuit uses a feedback circuit to realize the hysteresis function . The proposed detection circuit is implemented in 0.5 μm 65 V BCD process which occupies an active area of 590 μm ＆#215; 310 μm . The measured results show that the temperature coefficient of the threshold voltage is 26.5 ＆#215; 10- 6 / ℃ over the temperature range of - 40 ℃ to 125 ℃ . According to the measured results of 20 chips , the average value of the threshold voltage is 11.9 V ＆#177; 0.25 V , with a standard deviation of 0.138 V .