LTC3891 - Low IQ, 60V Synchronous Step-Down Controller

Features

  • Wide VIN Range: 4V to 60V (65V Abs Max)
  • Low Operating IQ: 50μA
  • Wide Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
  • RSENSE or DCR Current Sensing
  • Phase-Lockable Frequency (75kHz to 750kHz)
  • Programmable Fixed Frequency (50kHz to 900kHz)
  • Selectable Continuous, Pulse-Skipping or Low Ripple Burst Mode® Operation at Light Load
  • Selectable Current Limit
  • Very Low Dropout Operation: 99% Duty Cycle
  • Adjustable Output Voltage Soft-Start or Tracking
  • Power Good Output Voltage Monitor
  • Output Overvoltage Protection
  • Low Shutdown IQ: < 14μA
  • Internal LDO Powers Gate Drive from VIN or EXTVCC
  • No Current Foldback During Start-Up
  • Small 20-Pin 3mm × 4mm QFN and TSSOP Packages
Designed for Automotive and Transportation Applications
AEC-Q100 data available for specific packages


Typical Application

LTC3891 Typical Application
LTC3891 Typical Application

Description

The LTC3891 is a high performance step-down switching regulator DC/DC controller that drives an all N-channel synchronous power MOSFET stage. A constant frequency current mode architecture allows a phase-lockable frequency of up to 750kHz.

The 50μA no-load quiescent current extends operating run time in battery-powered systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of output capacitance and ESR values. The LTC3891 features a precision 0.8V reference and power good output indicator. A wide 4V to 60V input supply range encompasses a wide range of intermediate bus voltages and battery chemistries. The output voltage of the LTC3891 can be programmed between 0.8V to 24V.

The TRACK/SS pin ramps the output voltages during start-up. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The PLLIN/MODE pin selects among Burst Mode operation, pulse-skipping mode, or continuous conduction mode at light loads.

Packaging

For complete and up to date package information and drawings, please refer to our packaging page

Part Number Package Code Temp Package
Drawing
RoHS
LTC3891EFE#PBF TSSOP-20 FE E 05-08-1663 (CB) Yes
LTC3891EFE#TRPBF TSSOP-20 FE E 05-08-1663 (CB) Yes
LTC3891EUDC#PBF 3x4 QFN-20 UDC E 05-08-1742 Yes
LTC3891EUDC#TRPBF 3x4 QFN-20 UDC E 05-08-1742 Yes
LTC3891HFE#PBF TSSOP-20 FE H 05-08-1663 (CB) Yes
LTC3891HFE#TRPBF TSSOP-20 FE H 05-08-1663 (CB) Yes
LTC3891HUDC#PBF 3x4 QFN-20 UDC H 05-08-1742 Yes
LTC3891HUDC#TRPBF 3x4 QFN-20 UDC H 05-08-1742 Yes
LTC3891IFE#PBF TSSOP-20 FE I 05-08-1663 (CB) Yes
LTC3891IFE#TRPBF TSSOP-20 FE I 05-08-1663 (CB) Yes
LTC3891IUDC#PBF 3x4 QFN-20 UDC I 05-08-1742 Yes
LTC3891IUDC#TRPBF 3x4 QFN-20 UDC I 05-08-1742 Yes
LTC3891MPFE#PBF TSSOP-20 FE MP 05-08-1663 (CB) Yes
LTC3891MPFE#TRPBF TSSOP-20 FE MP 05-08-1663 (CB) Yes
LTC3891MPUDC#PBF 3x4 QFN-20 UDC MP 05-08-1742 Yes
LTC3891MPUDC#TRPBF 3x4 QFN-20 UDC MP 05-08-1742 Yes


LTC3891 Package Drawing
LTC3891 Package Drawing

Order Info

  • Part numbers ending in PBF are lead free. Solder plated terminal finish (SnPb) versions are non-standard and special terms and conditions and pricing applies if available. Please contact LTC marketing for information.
  • Part numbers containing TR or TRM are shipped in tape and reel or 500 unit mini tape and reel, respectively
  • Please refer to our general ordering information or the product datasheet for more details

Package Variations and Pricing

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC3891EFE#PBF TSSOP-20 E $5.22 $3.65 Yes
LTC3891EFE#TRPBF TSSOP-20 E $3.71 Yes
LTC3891EUDC#PBF 3x4 QFN-20 E $4.96 $3.47 Yes
LTC3891EUDC#TRPBF 3x4 QFN-20 E $3.53 Yes
LTC3891HFE#PBF TSSOP-20 H $6.39 $4.47 Yes
LTC3891HFE#TRPBF TSSOP-20 H $4.53 Yes
LTC3891HUDC#PBF 3x4 QFN-20 H $6.10 $4.27 Yes
LTC3891HUDC#TRPBF 3x4 QFN-20 H $4.33 Yes
LTC3891IFE#PBF TSSOP-20 I $5.97 $4.18 Yes
LTC3891IFE#TRPBF TSSOP-20 I $4.24 Yes
LTC3891IUDC#PBF 3x4 QFN-20 I $5.69 $3.98 Yes
LTC3891IUDC#TRPBF 3x4 QFN-20 I $4.04 Yes
LTC3891MPFE#PBF TSSOP-20 MP $15.64 $10.95 Yes
LTC3891MPFE#TRPBF TSSOP-20 MP $11.01 Yes
LTC3891MPUDC#PBF 3x4 QFN-20 MP $15.00 $10.50 Yes
LTC3891MPUDC#TRPBF 3x4 QFN-20 MP $10.56 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Demo Boards

Linear Technology offers many demo boards free of charge to qualified customers. Contact your local sales office or distributor to inquire about a demo board. Certain demo boards are also available for sale via credit card on this website. Demo boards are for evaluation purposes only. It remains the customer’s responsibility to verify proper and reliable operation in the actual end application.

Part Number Description Price Documentation
DC1695B LTC3891EFE Demo Board | 4.5V ≤ VIN ≤ 60V, VOUT = 3.3V @ 5A $150.00
DC1940A LTC3891EUDC Demo Board: 16V to 60V Input, VOUT = 12V at 15A $175.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

AEC-Q100 data is available for these specific part numbers. Please contact your local sales representative for more information regarding reliability reports or to inquire about parts that are not included. For more information, view our Automotive and Transportation page

Part Number Package Temp Price
(1-99)
Price
(1k)*
RoHS
LTC3891HFE#PBF TSSOP-20 H $6.39 $4.47 Yes
LTC3891HFE#TRPBF TSSOP-20 H $4.53 Yes
LTC3891HUDC#PBF 3x4 QFN-20 H $6.10 $4.27 Yes
LTC3891HUDC#TRPBF 3x4 QFN-20 H $4.33 Yes
LTC3891IFE#PBF TSSOP-20 I $5.97 $4.18 Yes
LTC3891IFE#TRPBF TSSOP-20 I $4.24 Yes
LTC3891IUDC#PBF 3x4 QFN-20 I $5.69 $3.98 Yes
LTC3891IUDC#TRPBF 3x4 QFN-20 I $4.04 Yes
LTC3891MPFE#PBF TSSOP-20 MP $15.64 $10.95 Yes
LTC3891MPFE#TRPBF TSSOP-20 MP $11.01 Yes
LTC3891MPUDC#PBF 3x4 QFN-20 MP $15.00 $10.50 Yes
LTC3891MPUDC#TRPBF 3x4 QFN-20 MP $10.56 Yes
Buy NowRequest Samples
* The USA list pricing shown is for BUDGETARY USE ONLY, shown in United States dollars (FOB USA per unit for the stated volume), and is subject to change. International prices may differ due to local duties, taxes, fees and exchange rates. For volume-specific price or delivery quotes, please contact your local Linear Technology sales office or authorized distributor.

Applications

  • Automotive Always-On Systems
  • Battery Powered Digital Devices
  • Distributed DC Power Systems

Product Notifications

Please login to your MyLinear account for notifications of datasheet updates, new document releases and LTspice model announcements for your favorite products. If you do not have a MyLinear account you may Sign Up Now.

Forgot your password? Click here.
Need help? Email mylinear@linear.com with questions and comments.

Design Tools

LTspice

LTspice® software is a powerful, fast and free simulation tool, schematic capture and waveform viewer with enhancements and models for improving the simulation of switching regulators. Click here to download LTspice

To launch a ready to run LTspice demonstration circuit for this part:

To explore other ready to run LTspice demonstration circuits, please visit our Demo Circuits Collection.

Models for the following parts are available in LTspice IV:
LTC3891

LTpowerCAD

The LTpowerCAD design tool is a complete power supply design tool program that can significantly ease the tasks of power supply design. It guides users to a solution, selects power stage components, provides detailed power efficiency, shows quick loop bode plot stability and load transient analysis, and can export a final design to LTspice for simulation. Click here to download LTpowerCAD

To open the project file for this circuit:

Design tools for the following parts are available in LTpowerCAD:
LTC3891

Technical Support