ADI ADM1275 2V-20V热插拔控制方案

ADI公司的ADM1275是2V-20V的热插拔控制器,能使电路板插入或拔出带电背板,控制电源电压为2V-20V,限流电阻可编程从5mV到25mV,12位ADC的精度为±1%,电荷泵栅极驱动器用来驱动多个外接N-沟FET,高栅极驱动电压保证了最低的RDSON,主要用在电源监视,电讯和数据通信设备,PC/服务器等.本文介绍了ADM1275主要特性,方框图,以及评估板EVAL-ADM127xEBZ主要特性,电路图,材料清单和PCB布局图.
The ADM1275 is a hot-swap controller that allows a circuit board to be removed from or inserted into a live backplane. It also features current and voltage readback via an integrated 12-bit analog-to-digital converter (ADC), accessed using a PMBus™ interface.
The load current is measured using an internal current sense amplifier that measures the voltage across a sense resistor in the power path via the SENSE+ and SENSE− pins. A default limit of 20 mV is set, but this limit can be adjusted, if required, using a resistor divider network from the internal reference voltage to the ISET pin.
The ADM1275 limits the current through the sense resistor by controlling the gate voltage of an external N-channel FET in the power path, via the GATE pin. The sense voltage—and, therefore, the load current—is maintained below the preset maximum. The ADM1275 protects the external FET by limiting the time that the FET remains on while the current is at its maximum value. This current limit time is set by the choice of capacitor connected to the TIMER pin. In addition, a foldback resistor network can be used to actively lower the current limit as the voltage across the FET is increased. This helps to maintain constant power in the FET and allows the safe operating area (SOA) to be adhered to in an effective manner.
In case of a short-circuit event, a fast internal overcurrent detec-tor responds within 370 ns and signals the gate to shut down. A 1500 mA pull-down device ensures a fast FET response. The ADM1275 features overvoltage and undervoltage protection, programmed using external resistor dividers on the UV...