LM1771   
Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation from the PowerWise® Family		 Click link to Download

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

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.

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
Also Recommended
LM1770▲SOT23 Package
LM2853▲3A Integrated FETs PWM Version



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                                              LM1771
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Also Recommended
LM1770▲SOT23 Package
LM2853▲3A Integrated FETs PWM Version

Typical Application
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Block Diagram
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Typical Performance
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Paramaters / ValuesLM1771 LM1770 LM2853
Output Current6000 mA 4000 mA 3000 mA
Input Min Voltage2.8 Volt 2.8 Volt 3 Volt
Input Max Voltage5.5 Volt 5.5 Volt 5.5 Volt
Feedback Voltage0.8 Volt 0.8 Volt Undefined Volt
Feedback Tolerance2 % 2 %
Frequency Min300 kHz 300 kHz 550 kHz
Frequency Max1000 kHz 1000 kHz 550 kHz
Efficiency (peak)95 % 95 % 95 %
Output Range0.8V to 4.5V 0.8V to 4.5V 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5
Adj Switch FrequencyNo No No
Adjustable OutputYes Yes No
Synchronous RectificationYes Yes Yes
On/Off PinYes No Yes
Error FlagNo No No
SoftStartYes Yes Yes
Sync PinNo No No
InvertingNo Yes No
FlybackNo No No
Lossless Current SenseNo No
RegTypeSwitching Controller Switching Controller Switching Regulator
Temperature Min-40 deg C -40 deg C -40 deg C
Temperature Max125 deg C 125 deg C 125 deg C
Channels1 Channels 1 Channels
Special FeaturesPrecision enable for sequencing multiple rails No compensation required Internal compensation, low standby current
TopologyBuck Buck Synchronous Buck
PWM ModeConstant on-time Constant on-time Voltage
Step-DownYes No Yes
Step-UpNo No
Output PowerUndefined Watt Undefined Watt
Output Max4.5 Volt 4.5 Volt 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5 Volt
Output Min0.8 Volt 0.8 Volt 1.8, 1, 2.5, 1.2, 0.8, 3.3, 3, 1.5 Volt
PowerWiseYes Yes Yes

Datasheet
TitleSizeDateOther
Language
LM1771 Low-Voltage Synchronous Buck Controller with Precision Enable and No External Compensation772
Kbytes		13-Oct-06日本語


Featured Application Notes
TitleSizeDateOther
Language
AN-1477: Application Note 1477 LM1771 Evaluation Board573
Kbytes		11-Jul-06 中文
AN-1677: Application Note 1677 LM1771 and LM3880 Based FPGA Power Supply Reference Design177
Kbytes		14-Jan-08 


More Application Notes
TitleSizeDateOther
Language
AN-1400: Application Note 1400 LM1770 Evaluation Board528
Kbytes		30-Sep-05 中文
AN-1414: Application Note 1414 LM1770 Design Reference750
Kbytes		8-Nov-05 中文

Part Number(s)
(NSID)		Top ViewAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM1771SMM/NOPB
LM1771SMM

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
DIGIKEYWorldwide0
FARNELLEurope and Asia30
RS COMPONENTSWorldwide180
$0.85 each at 1K+ pcsreel
of
1000
LM1771TMM/NOPB

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
DIGIKEYWorldwide650
FARNELLEurope and Asia746
FUTUREWorldwide1100
RS COMPONENTSWorldwide1000
$0.85 each at 1K+ pcsreel
of
1000
LM1771UMM/NOPB

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
AVNET-EMWorldwide970
DIGIKEYWorldwide1930
FARNELLEurope and Asia840
FUTUREWorldwide1100
RS COMPONENTSWorldwide995
$0.85 each at 1K+ pcsreel
of
1000
LM1771SMMX/NOPB

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
3500
LM1771TMMX/NOPB

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
3500
LM1771UMMX/NOPB

RoHS



MINI SOIC		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
3500
LM1771SSD/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
DIGIKEYWorldwide1400
FARNELLEurope and Asia50
RS COMPONENTSWorldwide250
$0.85 each at 1K+ pcsreel
of
1000
LM1771TSD/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
AVNET-EMWorldwide2000
DIGIKEYWorldwide1356
FARNELLEurope and Asia49
RS COMPONENTSWorldwide250
$0.85 each at 1K+ pcsreel
of
1000
LM1771USD/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

Samples
DistributorRegionQty
AVNET-EMWorldwide1000
DIGIKEYWorldwide1381
FARNELLEurope and Asia50
RS COMPONENTSWorldwide250
$0.85 each at 1K+ pcsreel
of
1000
LM1771SSDX/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
4500
LM1771TSDX/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
4500
LM1771USDX/NOPB

RoHS



LLP		Full production
Lead Time: 6 weeks

 
DistributorRegionQty
DIGIKEYWorldwide0
$0.85 each at 1K+ pcsreel
of
4500

Part Number(s)
(NSID)		DescriptionAvailabilityCurrent Reported StockBudgetary PricingStandard Pack Size
LM1771EVAL
Low-Voltage Synchronous Buck Controller with Precision Enable and No External CompensationFull production


 
DistributorRegionQty
DIGIKEYWorldwide0
NATIONALWorldwide237
$38.00 each1

Description:

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

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 mA
  • Internal soft-start
  • Short circuit protection
  • Tiny LLP-6 package and MSOP-8 package

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

Contents:

  • A fully assembled LM1771 eval board
  • LM1771 datasheet
  • LM1771 evaluation board appnote

Part Number(s)
(NSID)		Top ViewTypePinsMSL RatingPeak ReflowRoHSCAD SymbolsModelsPackage
Marking
Format
LM1771SMM/NOPB
LM1771SMM
MINI SOIC81
1		260
260		RoHSDownloadN/A
ZXTT
SNRB
LM1771TMM/NOPB
MINI SOIC81260RoHSDownloadN/A
ZXTT
SNSB
LM1771UMM/NOPB
MINI SOIC81260RoHSDownloadN/A
ZXTT
SNTB
LM1771SMMX/NOPB
MINI SOIC81260RoHSDownloadN/A
ZXTT
SNRB
LM1771TMMX/NOPB
MINI SOIC81260RoHSDownloadN/A
ZXTT
SNSB
LM1771UMMX/NOPB
MINI SOIC81260RoHSDownloadN/A
ZXTT
SNTB
LM1771SSD/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771S
LM1771TSD/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771T
LM1771USD/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771U
LM1771SSDX/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771S
LM1771TSDX/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771T
LM1771USDX/NOPB
LLP61260RoHSDownloadN/A
ZXYTT
1771U

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.


[Information as of 21-Nov-2009]