An Asynchronous Constant TOFF, 10 A, Buck Converter with Peak Current Mode Control for Automotive Applications

In recent years, in the automotive sector, devices that need a regulated DC supply voltage have increased. DCDC switching converters are the best solution in terms of performance, cost, and efficiency. Among DCDC converters, the Step-Down switching converter (or Buck converter) is very important. The high number of these devices installed on a car requires the reduction of the cost for the system, with a very simple implementation, but maintaining comparable performances with a more complex and expensive design. In this article, an Asynchronous Constant TOFF Peak Current Mode Controlled (PCMC) Buck converter, with a maximum output current of 10A, is presented. Thanks to this type of Pulse Frequency Modulation (PFM) control and an integrated high-side current sensing, it is possible to realize an efficient system with over-current protection, duty cycle greater than 50%, without slope compensations, and high efficiency also at low loads. The implementation of the integrated current sense, the high switching frequency and the high stability of constant TOFF reduce at the minimum the number of external components and the used area for IC to lower the price of the buck converter system. The Quasi-Constant switching frequency allows using a cheapest filter for automotive EMI tests. The system works with a switching frequency around 1MHz with a precise output voltage from 1. 8V to 5V with an output current up to 10A.