A Floating Peak Current Detection and Protection Circuit with Current Compensation, Dual Opening Mechanism and Negative Feedback
Yuxi Ma, Ying Zhang, Yujia Liang · 2024
Traditional circuits often suffer from significant peak current fluctuations due to sensitivity to temperature, process variations, and other conditions, leading to detection deviations that can damage the circuit. This paper presents the design of a peak current detection and protection circuit for a BUCK DC-DC converter. A current compensation structure is proposed to reduce peak current fluctuations, ensuring the desired peak current is achieved. This implementation uses different proportions of positive and negative temperature coefficient resistors to control branch current changes due to temperature and provide current compensation. Additionally, a dual opening mechanism is employed. The high-side switch transistor is activated only when both the external control signal and the floating voltage conditions are simultaneously met, ensuring the proper response of the circuit's floating logic. As a result, the inductor is charged, the inductor's current rises, and peak current detection begins. The detection mechanism continuously monitors current changes throughout the process. When the current reaches the preset peak, logic signals control the high-side switch transistor to turn off, preventing further current increase and ensuring the converter circuit operates within the normal current range. Given that the left end of the inductor is at a floating potential, a level shift circuit is designed to switch the voltage between floating and ground logic, also serving as a negative feedback control logic. This circuit is implemented using a 180 nm BCD process. Simulation results show that, with an input voltage of 18 V, the circuit detects a stable peak current of 3.9 A, and logic signals control the circuit switching state to prevent further current increase, thereby achieving the goal of protecting the circuit.