LM1771 - Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation from the PowerWise® Family
Datasheet Packaging Samples & Pricing Eval. Boards Reliability Application Notes Knowledge Base

Features
•Input voltage range of 2.8V to 5.5V
•0.8V reference voltage
•Precision enable
•No compensation 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

General Description

The LM1771 is an efficient synchronous buck switching controller with a precision enable requiring no external compensation. More...


Applications

•Simple To Design, High Efficiency Step Down Switching Regulators
•FPGAs, DSPs, and ASIC Power Supplies
•Set-Top Boxes
•Cable Modems
•Printers
•Digital Video Recorders
•Servers
•Graphic Cards
  Typical Application
*click for larger image


ParametersValues
Output Current 6000 mA
Input Min Voltage 2.8 Volt
Input Max Voltage 5.5 Volt
Feedback Voltage 0.8 Volt
Feedback Tolerance 2 %
Frequency Min 300 kHz
Frequency Max 1000 kHz
Efficiency (peak) 95 %
Output Range 0.8V to 4.5V
Adj Switch Frequency No
Adjustable Output Yes
Synchronous Rectification Yes
On/Off Pin Yes
Error Flag No
SoftStart Yes
Sync Pin No
Inverting No
Flyback No
Lossless Current Sense No
RegType Switching Controller
Temperature Min -40 deg C
Temperature Max 125 deg C
Channels 1 Channels
Special Features Precision enable for sequencing multiple rails
Topology Buck
PWM Mode Constant on-time
Step-Down Yes
Step-Up No
Output Power Undefined Watt
Output Max 4.5 Volt
Output Min 0.8 Volt
PowerWise Yes


Typical Performance

*click for larger image


  Also Recommended
LM1770▲SOT23 Package
LM2853▲3A Integrated FETs PWM Version
Additional Resources
Application Notes


Block Diagram

*click for larger image



Datasheet
RoHS Compliance Information Size in KbytesDate Click link below to Download
LM1771 Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation 772
Kbytes		 13-Oct-06 Download
LM1771 Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation (Japanese)
 540 Kbytes   Download

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Package Availability, Models, Samples & Pricing
Part NumberPackageFactory Lead TimeModelsSamples &
Electronic
Orders		Budgetary PricingStd
Pack
Size		Package
Marking
Format
TypePinsSpec.MSL
Rating		Peak
Reflow		RoHS
Report		CAD
Symbols		WeeksQtyQty$US each
LM1771EVALLow-Voltage Synchronous Buck Controller with Precision Enable and No External CompensationFull productionN/A
 
Buy Now 		1+$38.001-
8 weeksN/A
LM1771SMMMINI SOIC8NOPB
STD		1
1		260
260		RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXTT
SNRB
6 weeks1000
LM1771TMMMINI SOIC8NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXTT
SNSB
6 weeks2500
LM1771UMMMINI SOIC8NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXTT
SNTB
6 weeks1000
LM1771SMMXMINI SOIC8NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
3500		ZXTT
SNRB
6 weeksN/A
LM1771TMMXMINI SOIC8NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
3500		ZXTT
SNSB
6 weeksN/A
LM1771UMMXMINI SOIC8NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
3500		ZXTT
SNTB
6 weeksN/A
LM1771SSDLLP6NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXYTT
1771S
6 weeks50000
LM1771TSDLLP6NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXYTT
1771T
6 weeks2000
LM1771USDLLP6NOPB1260RoHS Download Full productionN/A
Samples
Buy Now 		1K+$0.85reel
of
1000		ZXYTT
1771U
6 weeks75000
LM1771SSDXLLP6NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
4500		ZXYTT
1771S
6 weeks5000
LM1771TSDXLLP6NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
4500		ZXYTT
1771T
6 weeksN/A
LM1771USDXLLP6NOPB1260RoHS Download Full productionN/A
 
Buy Now 		1K+$0.85reel
of
4500		ZXYTT
1771U
6 weeksN/A

General Description

The LM1771 is an efficient synchronous buck switching controller with a precision enable requiring no external compensation. The constant on-time control scheme provides a simple design free of compensation components, allowing minimal component 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 100kHz to 1000kHz.

Reliability Metrics

Part Number Process EFR Reject EFR Sample Size PPM LTA Rejects LTA Device Hours FITS MTTF (Hours)
LM1771SMMCS065238968520440200011249079519
LM1771SMMXCS065238968520440200011249079519
LM1771SSDCS065238968520440200011249079519
LM1771SSDXCS065238968520440200011249079519
LM1771TMMCS065238968520440200011249079519
LM1771TMMXCS065238968520440200011249079519
LM1771TSDCS065238968520440200011249079519
LM1771TSDXCS065238968520440200011249079519
LM1771UMMCS065238968520440200011249079519
LM1771UMMXCS065238968520440200011249079519
LM1771USDCS065238968520440200011249079519
LM1771USDXCS065238968520440200011249079519

Note: The Early Failure Rates (EFR) were calculated as point estimate PPM based on rejects and sample size for EFR. The Long Term Failure Rates were calculated at 60% confidence using the Arrhenius equation at 0.7eV activation energy and derating the assumed stress temperature of 150°C to an application temperature of 55°C.

For more information on Reliability Metrics, please click here.


Application Notes

TitleSize in Kbytes Date Click link below to Download
AN-1477: Application Note 1477 LM1771 Evaluation Board 573
Kbytes		 11-Jul-06 Download
AN-1477 (Chinese): Application Note 1477 LM1771 Evaluation Board
 218 Kbytes  
AN-1677: Application Note 1677 LM1771 and LM3880 Based FPGA Power Supply Reference Design 177
Kbytes		 14-Jan-08 Download

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More Application Notes

TitleSize in Kbytes Date Click link below to Download
AN-1400: Application Note 1400 LM1770 Evaluation Board 528
Kbytes		 30-Sep-05 Download
AN-1400 (Chinese): Application Note 1400 LM1770 Evaluation Board
 207 Kbytes  
AN-1414: Application Note 1414 LM1770 Design Reference 750
Kbytes		 8-Nov-05 Download
AN-1414 (Chinese): Application Note 1414 LM1770 Design Reference
 471 Kbytes  

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[Information as of 7-Nov-2009]