The invention belongs to the field of
power management and relates to a DC-DC step-down converter, in particular to a synchronous rectification step-down converter
chip with a high-precision current detection function. The
chip is based on a current PWM-mode DC-DC step-down converter. In the
chip, the synchronous rectification switch PWM-mode current control technology is adopted, so the efficiency of the converter is greatly improved, and the output current can reach 2 A. By the adoption of a novel current detection sensing module with extremely high precision, the magnitude of a current can be detected more accurately in time, and the chip can be subjected to reliable
overcurrent protection. Besides, according to the design of the chip, a double-frequency oscillator is adopted, so the frequency of a switching tube can be selected automatically according to the
load capacity, the efficiency of the chip can be improved, and the working time of the chip can be prolonged. Lastly, the chip integrates a soft start circuit, so a surge current and an overshoot
voltage which are generated during start can be suppressed, and an
LED lamp and a driving chip can be protected against damage.