LT1172 - 100kHz, 5A, 2.5A and 1.25A High Efficiency Switching Regulators


  • Wide Input Voltage Range: 3V to 60V
  • Low Quiescent Current: 6mA
  • Internal 5A Switch
    (2.5A for LT1171, 1.25A for LT1172)
  • Shutdown Mode Draws Only 50μA Supply Current
  • Very Few External Parts Required
  • Self-Protected Against Overloads
  • Operates in Nearly All Switching Topologies
  • Flyback-Regulated Mode Has Fully Floating Outputs
  • Comes in Standard 5-Pin Packages
  • LT1172 Available in 8-Pin MiniDIP and Surface Mount Packages
  • Can Be Externally Synchronized

Typical Application

LT1172 Typical Application
LT1172 Typical Application


The LT®1170/LT1171/LT1172 are monolithic high power switching regulators. They can be operated in all standard switching configurations including buck, boost, flyback, forward, inverting and “Cuk.” A high current, high efficiency switch is included on the die along with all oscillator, control and protection circuitry. Integration of all functions allows the LT1170/LT1171/LT1172 to be built in a standard 5-pin TO-3 or TO-220 power package as well as the 8-pin packages (LT1172). This makes them extremely easy to use and provides “bust proof” operation similar to that obtained with 3-pin linear regulators.

The LT1170/LT1171/LT1172 operate with supply voltages from 3V to 60V, and draw only 6mA quiescent current. They can deliver load power up to 100W with no external power devices. By utilizing current-mode switching techniques, they provide excellent AC and DC load and line regulation.

The LT1170/LT1171/LT1172 have many unique features not found even on the vastly more difficult to use low power control chips presently available. They use adaptive antisat switch drive to allow very wide ranging load currents with no loss in efficiency. An externally activated shutdown mode reduces total supply current to 50μA typically for standby operation.


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
LT1172CN8#PBF N-8 N C 05-08-1510 (N8) Yes
LT1172CQ#PBF DDPAK-5 Q C 05-08-1461 Yes
LT1172CQ#TRPBF DDPAK-5 Q C 05-08-1461 Yes
LT1172CS8#PBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1172CS8#TRPBF SO-8 S8 C 05-08-1610 (S8) Yes
LT1172CSW#PBF SW-16 SW C 05-08-1620 (SW16) Yes
LT1172CSW#TRPBF SW-16 SW C 05-08-1620 (SW16) Yes
LT1172CT#06PBF TO-220 T C 05-08-1421 (Flow 06) Yes
LT1172CT#31PBF TO-220 T C 05-08-1421 (Flow 06) Yes
LT1172CT#PBF TO-220 T C 05-08-1421 (Std) Yes
LT1172HVCQ#PBF DDPAK-5 Q C 05-08-1461 Yes
LT1172HVCQ#TRPBF DDPAK-5 Q C 05-08-1461 Yes
LT1172HVCT#06PBF TO-220 T C 05-08-1421 (Flow 06) Yes
LT1172HVCT#30PBF TO-220 T C 05-08-1421 (Std) Yes
LT1172HVCT#31PBF TO-220 T C 05-08-1421 (Std) Yes
LT1172HVCT#PBF TO-220 T C 05-08-1421 (Std) Yes
LT1172HVIQ#PBF DDPAK-5 Q I 05-08-1461 Yes
LT1172HVIQ#TRPBF DDPAK-5 Q I 05-08-1461 Yes
LT1172IN8#PBF N-8 N I 05-08-1510 (N8) Yes
LT1172IS8#PBF SO-8 S8 I 05-08-1610 (S8) Yes
LT1172IS8#TRPBF SO-8 S8 I 05-08-1610 (S8) Yes

LT1172 Package Drawing
LT1172 Package Drawing
LT1172 Package Drawing
LT1172 Package Drawing
LT1172 Package Drawing
LT1172 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
LT1172CN8#PBF N-8 C $2.92 $2.35 Yes
LT1172CQ#PBF DDPAK-5 C $4.25 $3.45 Yes
LT1172CQ#TRPBF DDPAK-5 C $3.57 Yes
LT1172CS8#PBF SO-8 C $3.58 $2.90 Yes
LT1172CS8#TRPBF SO-8 C $2.96 Yes
LT1172CSW#PBF SW-16 C $3.58 $2.90 Yes
LT1172CSW#TRPBF SW-16 C $2.96 Yes
LT1172CT#06PBF TO-220 C $3.75 $2.90 Yes
LT1172CT#31PBF TO-220 C $4.20 $3.35 Yes
LT1172CT#PBF TO-220 C $3.75 $2.90 Yes
LT1172HVCQ#PBF DDPAK-5 C $6.52 $4.55 Yes
LT1172HVCQ#TRPBF DDPAK-5 C $4.67 Yes
LT1172HVCT#06PBF TO-220 C $4.92 $3.80 Yes
LT1172HVCT#30PBF TO-220 C $5.37 $4.25 Yes
LT1172HVCT#31PBF TO-220 C $5.37 $4.25 Yes
LT1172HVCT#PBF TO-220 C $4.92 $3.80 Yes
LT1172HVIQ#PBF DDPAK-5 I $7.09 $4.95 Yes
LT1172HVIQ#TRPBF DDPAK-5 I $5.07 Yes
LT1172IN8#PBF N-8 I $4.08 $3.30 Yes
LT1172IS8#PBF SO-8 I $4.67 $3.80 Yes
LT1172IS8#TRPBF SO-8 I $3.86 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.

Click here to view our complete list of demo boards


  • Logic Supply 5V at 10A
  • 5V Logic to ±15V Op Amp Supply
  • Battery Upconverter
  • Power Inverter (+ to –) or (– to +)
  • Fully Floating Multiple Outputs
This data sheet is only intended to provide specifications, graphs, and a general functional description of the LT1170/LT1171/LT1172. Application circuits are included to show the capability of the LT1170/LT1171/LT1172. A complete design manual (AN19) should be obtained to assist in developing new designs. This manual contains a comprehensive discussion of both the LT1070 and the external components used with it, as well as complete formulas for calculating the values of these components. The manual can also be used for the LT1170/LT1171/LT1172 by factoring in the higher frequency. A CAD design program called SwitcherCAD® is also available.

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 with questions and comments.

Design Tools


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:

Technical Support