MAX8646

19-3971; Rev 2; 10/07 6A, 2MHz Step-Down Regulator with Integrated Switches General Description The MAX8646 high-efficiency switching regulator delivers up to 6A load current at output voltages from 0.6V to 0.9 x VIN. The IC operates from 2.35V to 3.6V, making it ideal for on-board point-of-load and postregulation applications. Total output error is less than ±1% over load, line, and temperature ranges. The MAX8646 features fixed-frequency PWM mode operation with a switching frequency range of 500kHz to 2MHz set by an external resistor. High-frequency operation allows for an all-ceramic capacitor design. The high operating frequency also allows for small-size external components. The low-resistance on-chip nMOS switches ensure high efficiency at heavy loads while minimizing critical inductances, making the layout a much simpler task with respect to discrete solutions. Following a simple layout and footprint ensures first-pass success in new designs. The MAX8646 comes with a high bandwidth (> 14MHz) voltage-error amplifier. The voltage-mode control architecture and the voltage-error amplifier permit a type III compensation scheme to be utilized to achieve maximum loop bandwidth, up to 20% of the switching frequency. High loop bandwidth provides fast transient response, resulting in less required output capacitance and allowing for all-ceramic-capacitor designs. The MAX8646 provides two tri-state logic inputs to select one of nine preset output voltages. The preset output volt...