LTC3638 - High Efficiency, 140V 250mA Step-Down Regulator


  • Wide Operating Input Voltage Range: 4V to 140V
  • Internal Low Resistance Power MOSFET
  • No Compensation Required
  • Adjustable 20mA to 250mA Maximum Output Current
  • Low Dropout Operation: 100% Duty Cycle
  • Low Quiescent Current: 12μA
  • Wide Output Range: 0.8V to VIN
  • 0.8V ±1% Feedback Voltage Reference
  • Precise RUN Pin Threshold
  • Internal or External Soft-Start
  • Programmable 1.8V, 3.3V, 5V or Adjustable Output
  • Few External Components Required
  • Programmable Input Overvoltage Lockout
  • Thermally Enhanced High Voltage MSOP Package

Typical Application

LTC3638 Typical Application
LTC3638 Typical Application


The LTC®3638 is a high efficiency step-down DC/DC regulator with internal power switch that draws only 12μA typical DC supply current while maintaining a regulated output voltage at no load.

The LTC3638 can supply up to 250mA load current and features a programmable peak current limit that provides a simple method for optimizing efficiency and for reducing output ripple and component size. The LTC3638’s combination of Burst Mode® operation, integrated power switch, low quiescent current, and programmable peak current limit provides high efficiency over a broad range of load currents.

With its wide input range of 4V to 140V and programmable overvoltage lockout, the LTC3638 is a robust regulator suited for regulating from a wide variety of power sources. Additionally, the LTC3638 includes a precise run threshold and soft-start feature to guarantee that the power system start-up is well-controlled in any environment. A feedback comparator output enables multiple LTC3638s to be connected in parallel for higher current applications.

The LTC3638 is available in a thermally enhanced high voltage-capable 16-lead MSE package with four missing pins.


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

Part Number Package Code Temp Package
LTC3638EMSE#PBF MS-16E MSE E 05-08-1871 RoHS
LTC3638EMSE#TRPBF MS-16E MSE E 05-08-1871 RoHS
LTC3638HMSE#PBF MS-16E MSE H 05-08-1871 RoHS
LTC3638HMSE#TRPBF MS-16E MSE H 05-08-1871 RoHS
LTC3638IMSE#PBF MS-16E MSE I 05-08-1871 RoHS
LTC3638IMSE#TRPBF MS-16E MSE I 05-08-1871 RoHS
LTC3638MPMSE#PBF MS-16E MSE MP 05-08-1871 RoHS
LTC3638MPMSE#TRPBF MS-16E MSE MP 05-08-1871 RoHS

LTC3638 Package Drawing

Order Info

Package Variations and Pricing

Part Number Package Temp Price
LTC3638EMSE#PBF MS-16E E $5.22 $3.65 View
LTC3638EMSE#TRPBF MS-16E E $3.71 View
LTC3638HMSE#PBF MS-16E H $6.10 $4.27 View
LTC3638HMSE#TRPBF MS-16E H $4.33 View
LTC3638IMSE#PBF MS-16E I $5.74 $4.02 View
LTC3638IMSE#TRPBF MS-16E I $4.08 View
LTC3638MPMSE#PBF MS-16E MP $15.49 $10.84 View
LTC3638MPMSE#TRPBF MS-16E MP $10.90 View
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
DC2057A LTC3638 Demo Board | 4V ≤ VIN ≤ 140V, Vout = 1.8V/3.3V/5V/Adj @ 250mA $200.00
Buy Now
Click here to view our complete list of demo boards


  • Industrial Control Supplies
  • Medical Devices
  • Distributed Power Systems
  • Portable Instruments
  • Battery-Operated Devices
  • Avionics
  • Automotive

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® IV 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 IV

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

  • Step 1: If you have not installed LTspice on this computer, download and install LTspice IV
  • Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
  • Step 3: If LTspice IV does not automatically open after clicking the link above, you can instead run the simulation by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTspice and open the demonstration circuit by selecting 'Open' from the 'File' menu

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:

Technical Support