LM1771 Datasheet | National Semiconductor

Description The LM1771 is an efficient synchronous buck switching controller with a precision enable requiring no external pensation. The constant on-time control scheme provides a simple design free of pensation ponents, allowing minimal ponent count and board space. The precision enable pin allows flexibility in sequencing multiple rails and setting UVLO. The LM1771 also incorporates a unique input feed-forward to maintain a constant frequency independent of the input voltage. The LM1771 is optimized for a low voltage input range of 2.8V to 5.5V and can provide an adjustable output as low as 0.8V. Driving an external high side PFET and low side NFET it can provide efficiencies as high as 95%. Three versions of the LM1771 are available depending on the switching frequency desired for the application. Nominal switching frequencies are in the range of 100k Hz to 1000k Hz. Features n n n n n n n n n Input voltage range of 2.8V to 5.5V 0.8V reference voltage Precision enable No pensation required Constant frequency across input range Low quiescent current of 400 µA Internal soft-start Short circuit protection Tiny LLP-6 package and MSOP-8 package Applications n Simple To Design, High Efficiency Step Down Switching Regulators n FPGAs, DSPs, and ASIC Power Supplies n Set-Top Boxes n Cable Modems n Printers n Digital Video Recorders n Servers n Graphic Cards Typical Application Circuit © 2006 National Semiconductor Corporation DS201890 .national. .. Connection Diagrams Top View Top View MSOP-8 NS Package Number MUA08A 6-Lead LLP (3mm x 3mm) NS Package Number SDE06A Ordering Information Order Number LM1771SSD LM1771SSDX LM1771TSD LM1771TSDX LM1771USD LM1771USDX Order Number LM1771SMM LM1771SMMX LM1771TMM LM1771TMMX LM1771UMM LM1771UMMX Timing Option 500ns 1000ns 2000ns Timing Option 500ns 1000ns 2000ns MSOP-8 MUA08A Available Soon Package Type 6-Lead LLP SDE06A Package Type NSC Package Drawing Top Mark 1771S 1771S 1771T 1771T...