NS LM5118寬電壓升/降壓電源方案

The LM5118 wide voltage range Buck-Boost switching regulator controller features all of the functions necessary to implement a high performance, cost efficient Buck-Boost regulator using a minimum of external components. The Buck-Boost topology maintains output voltage regulation when the input voltage is either less than or greater than the output voltage making it especially suitable for automotive applications. The LM5118 operates as a buck regulator while the input voltage is sufficiently greater than the regulated output voltage and gradually transitions to the buck-boost mode as the input voltage approaches the output. This dual mode approach maintains regulation over a wide range of input voltages with optimal conversion efficiency in the buck mode and a glitch-free output during mode transitions. This easy to use controller includes drivers for the high side buck MOSFET and the low side boost MOSFET. The regulator’s control method is based upon current mode control utilizing an emulated current ramp. Emulated current mode control reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable control of the very small duty cycles necessary in high input voltage applications. Additional protection features include current limit, thermal shutdown and an enable input. The device is available in a power enhanced TSSOP-20 package featuring an exposed die attach pad to aid thermal dissipation.
LM5118主要特性:
■ Ultra-wide input voltage range from 3V to 75V
■ Emulated peak current mode control
■ Smooth transition between step-down and step- up modes
■ Switching frequency programmable to 500KHz
■ Oscillator synchronization capability
■ Internal high voltage bias regulator
■ Integrated high and low-side gate drivers
■ Programmable soft-start time
■ Ultra low shutdown current
■ Enable input wide bandwidth error amplifier
■ 1.5% feedback reference accuracy
■ Thermal shutdown





圖1.LM5118方框圖和典型應用電路圖



圖2.12V/3A典型應用電路圖