Part # LM1771 datasheet

Part Manufacturer: National Semiconductor

National Semiconductor

Part Description: LM1771 Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation

Part Details:

Compensation LM1771 October 2006 Low-V LM1771Low-Voltage Synchronous Buck Controller with oltage Precision Enable and No External CompensationGeneral Description Features The LM1771 is an efficient synchronous buck switching con- n Input voltage range of 2.8V to 5.5V Synchronous troller with a precision enable requiring no external compen- n 0.8V reference voltage sation. The constant on-time control scheme provides a n Precision enable simple design free of compensation components, allowing n No compensation required minimal component count and board space. The precision n Constant frequency across input range enable pin allows flexibility in sequencing multiple rails and n Low quiescent current of 400 µA setting UVLO. The LM1771 also incorporates a unique inputfeed-forward to maintain a constant frequency independent n Internal soft-start of the input voltage. The LM1771 is optimized for a low n Short circuit protection voltage input range of 2.8V to 5.5V and can provide an n Tiny LLP-6 package and MSOP-8 package adjustable output as low as 0.8V. Driving an external high Buck side PFET and low side NFET it can provide efficiencies as Applications high as 95%. n Simple To Design, High Efficiency Step Down Switching Three versions of the LM1771 are available depending on Regulators the switching frequency desired for the application. Nominal Controller n FPGAs, DSPs, and ASIC Power Supplies switching frequencies are in the range of 100kHz to n Set-Top Boxes 1000kHz. n Cable Modems n Printers n Digital Video Recorders n Servers n Graphic Cards with Typical Application Circuit Precision Enable and No External 20189001 © 2006 National Semiconductor Corporation

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LM1771.pdf Datasheet