LTC7812 - Low IQ, 38V Synchronous Boost+Buck Controller

Features

  • Synchronous Boost and Buck Controllers
  • When Cascaded, Allows VIN Above, Below or Equal to Regulated VOUT
  • Output Remains in Regulation Through Input Dips (e.g., Cold Crank) Down to 2.5V
  • Wide Bias Input Voltage Range: 4.5V to 38V
  • Low Input and Output Ripple
  • Low EMI
  • Fast Output Transient Response
  • High Light Load Efficiency
  • Low Operating IQ: 33μA (Both Channels On)
  • Low Operating IQ: 28μA (Buck Channel On)
  • RSENSE or Lossless DCR Current Sensing
  • Buck Output Voltage Range: 0.8V ≤ VOUT ≤ 24V
  • Boost Output Voltage Up to 60V
  • Phase-Lockable Frequency (75kHz to 850kHz)
  • Small 32-Pin 5mm × 5mm QFN Package
Designed for Automotive and Transportation Applications
AEC-Q100 generic family data available for specific packages


Typical Application

LTC7812 Typical Application

Description

The LTC®7812 is a high performance synchronous Boost+Buck DC/DC switching regulator controller that drives all N-channel power MOSFET stages. It contains independent step-up (boost) and step-down (buck) controllers that can regulate two separate outputs or be cascaded to regulate an output voltage from an input voltage that can be above, below or equal to the output voltage. The LTC7812 operates from a wide 4.5V to 38V input supply range. When biased from the output of the boost regulator, the LTC7812 can operate from an input supply as low as 2.5V after start-up. The 33μA no-load quiescent current extends operating run time in battery-powered systems.

Unlike conventional buck-boost regulators, the LTC7812’s cascaded Boost+Buck solution has continuous, nonpulsating, input and output currents, substantially reducing voltage ripple and EMI. The LTC7812 has independent feedback and compensation points for the boost and buck regulation loops, enabling a fast output transient response that can be easily optimized externally.

Packaging

CAD Symbols and Footprints: The downloadable Zip file below contains the schematic symbol and PCB footprints.

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

Part Number Package Code Temp Package
Drawing
RoHS
LTC7812EUH#PBF 5x5 QFN-32 UH E 05-08-1693 Yes
LTC7812EUH#TRPBF 5x5 QFN-32 UH E 05-08-1693 Yes
LTC7812HUH#PBF 5x5 QFN-32 UH H 05-08-1693 Yes
LTC7812HUH#TRPBF 5x5 QFN-32 UH H 05-08-1693 Yes
LTC7812IUH#PBF 5x5 QFN-32 UH I 05-08-1693 Yes
LTC7812IUH#TRPBF 5x5 QFN-32 UH I 05-08-1693 Yes


LTC7812 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
LTC7812EUH#PBF 5x5 QFN-32 E $5.71 $4.00 Yes
LTC7812EUH#TRPBF 5x5 QFN-32 E $4.06 Yes
LTC7812HUH#PBF 5x5 QFN-32 H $6.56 $4.59 Yes
LTC7812HUH#TRPBF 5x5 QFN-32 H $4.65 Yes
LTC7812IUH#PBF 5x5 QFN-32 I $6.13 $4.29 Yes
LTC7812IUH#TRPBF 5x5 QFN-32 I $4.35 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
DC2422A-A LTC7812EUH Demo Board | Sync Buck + Sync Boost, 4V ≤ VIN ≤ 36V; VOUT = 12V @ 8A $200.00
DC2422A-B LTC7812EUH Demo Board | Sync Boost + Sync Buck, 4V ≤ VIN ≤ 36V; VOUT1 (Quasi Regulated) = 10V-16V @ 6-8A $200.00
DC2422A-C LTC7812EUH Demo Board | Sync Boost + Sync Buck, 4V ≤ VIN ≤ 36V; VBoost = 12V, Vbuck = 12V to 5V @ 8A $150.00
Buy Now
Click here to view our complete list of demo boards

Designed for Automotive and Transportation Applications

Please contact your local sales representative for more information regarding reliability reports and AEC-Q100 data 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
LTC7812EUH#PBF 5x5 QFN-32 E $5.71 $4.00 Yes
LTC7812EUH#TRPBF 5x5 QFN-32 E $4.06 Yes
LTC7812HUH#PBF 5x5 QFN-32 H $6.56 $4.59 Yes
LTC7812HUH#TRPBF 5x5 QFN-32 H $4.65 Yes
LTC7812IUH#PBF 5x5 QFN-32 I $6.13 $4.29 Yes
LTC7812IUH#TRPBF 5x5 QFN-32 I $4.35 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 and Industrial Power Systems
  • High Power Battery Operated Systems

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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

Models for the following parts are available in LTspice:
LTC7812

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:
LTC7812(Boost)
LTC7812(Buck)

Technical Support