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 T OFF 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 T OFF 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.