描述 Description

The LX1671 is a highly integrated power supply controller IC featuring three PWM switching regulator stages with an additional onboard linear regulator driver. Two of the constant frequency voltage-mode PWM phases can be configured for a single biphase high current output or two in-dependently regulated outputs. Each phase incorporates a fully programmable softstart sequence. This versatility yields either three or four independently regulated outputs with full power sequencing capability giving system designers the ultimate flexibility in power supply design.In biphase operation, the high current (>30A) output can utilize different supply rails allowing Forced Current Sharing? from different sources. Power loss and noise, due to the ESR of the input capacitors, are minimized by operating each PWM output 180° out of phase. This architecture also minimizes capacitor requirements while maximizing regulator response. The additional outputs are capable of supplying up to 5A (Linear Regulator Driver) and 15A (Switching Regulator) for I/O, memory, termination, and other supplies surrounding today’s microprocessor designs.Each regulator voltage output is programmed via a simple voltage-divider network. The LX1671, utilizing MOSFET RDS(ON) impedance, monitors current limit conditions, in each PWM phase, without the use of expensive current sense resistors.The LX1671 was designed to give system engineers maximum flexibility with respect to MOSFET supply. Each phase can utilize different supply voltages for efficient use of available supply rails. Additionally, when two phases are configured in biphase output, Ratio Current Sharing? can be programmed via inductor ESR selection. There are three other methods that can also be used for Ratio Current Sharing. These other methods are presented in the theory of operation section of this data sheet. ? U.S Patent #US6285571 (Forced Current Sharing), #US6292378 (Ratio Current Sharing).Key