Fast transient response high-accuracy current-sensing technique for step-up DC–DC converter

摘要

A novel current-sensing technique with fast transient and high accuracy for a step-up DC-DC converter is presented. This circuitry is applied for sensing the current flowing through the equivalent series resistor (ESR) of the inductor to obtain the inductor current information. It is achieved with a fast transient response circuit (FTRC), an operational amplifier, a current-sensing stage and an overshoot current protection circuit. The process offsets of the transistors, which can increase the current-sensing accuracy, and provide an additional current feedback loop to decrease the transient response time are compensated by the FTRC. When the sensed current is higher than the maximum value, the overcurrent protection (OCP) will be operating to let it shut down. This current-sensing technique has been integrated in a step-up DC-DC converter with standard 0.35 μm CMOS process. Experimental results show that the accuracy is higher than 98% and the transient response recovery time is ~100 μs with load current changing from 3 A to 10 mA.