LT3505 - 1.2A, Step-Down Switching Regulator in 3mm x 3mm DFN
Features
- Wide Input Range: 3.6V to 36V Operating, 40V Maximum
- Up to 1.2A Output Current
- Resistor-Programmable Fixed-Frequency Operation from 200kHz to 3MHz
- Output Adjustable Down to 780mV
- Short-Circuit Robust
- Uses Tiny Capacitors and Inductors
- Soft-Start
- Low Shutdown Current: <2µA
- Low VCESAT Switch: 350mV at 1A
- Thermally Enhanced, Low Profile 3mm x 3mm DFN-8 and MSOP-8 Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LT3505 is a current mode PWM step-down DC/DC converter with an internal 1.4A power switch. The wide operating input range of 3.6V to 36V (40V maximum) makes the LT3505 ideal for regulating power from a wide variety of sources, including unregulated wall transformers, 24V industrial supplies and automotive batteries. The oscillator can be programmed for high frequency operation allowing the use of tiny, low cost external components or it can be programmed for lower frequency operation to maximize efficiency.
Cycle-by-cycle current limit provides protection against shorted outputs and soft-start eliminates input current surge during start-up. The low current (<2µA) shutdown mode provides output disconnect, enabling easy power management in battery-powered systems.
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 |
|---|---|---|---|---|---|
| LT3505EDD#PBF | 3x3 DFN-8 | DD | E | 05-08-1698 | Yes |
| LT3505EDD#TRPBF | 3x3 DFN-8 | DD | E | 05-08-1698 | Yes |
| LT3505EMS8E#PBF | MS-8 | MS8 | E | 05-08-1660 | Yes |
| LT3505EMS8E#TRPBF | MS-8 | MS8 | E | 05-08-1660 | Yes |
| LT3505IDD#PBF | 3x3 DFN-8 | DD | I | 05-08-1698 | Yes |
| LT3505IDD#TRPBF | 3x3 DFN-8 | DD | I | 05-08-1698 | Yes |
| LT3505IMS8E#PBF | MS-8 | MS8 | I | 05-08-1660 | Yes |
| LT3505IMS8E#TRPBF | MS-8 | MS8 | I | 05-08-1660 | Yes |
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 | |
|---|---|---|---|---|---|---|
| LT3505EDD#PBF | 3x3 DFN-8 | E | $3.43 | $2.40 | Yes | |
| LT3505EDD#TRPBF | 3x3 DFN-8 | E | $2.46 | Yes | ||
| LT3505EMS8E#PBF | MS-8 | E | $3.71 | $2.60 | Yes | |
| LT3505EMS8E#TRPBF | MS-8 | E | $2.66 | Yes | ||
| LT3505IDD#PBF | 3x3 DFN-8 | I | $4.11 | $2.88 | Yes | |
| LT3505IDD#TRPBF | 3x3 DFN-8 | I | $2.94 | Yes | ||
| LT3505IMS8E#PBF | MS-8 | I | $4.40 | $3.08 | Yes | |
| LT3505IMS8E#TRPBF | MS-8 | I | $3.14 | Yes | ||
| Buy Now • Request Samples | ||||||
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 |
|---|---|---|---|
| DC1023A | LT3505EDD Demo Board | 6V ≤ VIN ≤ 36V, VOUT = 5V @ 1A | $100.00 | |
| DC1395A | LT3505 HV Buck regulator board with plug in interface | Contact Factory | |
| Buy Now | |||
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 | |
|---|---|---|---|---|---|---|
| LT3505IDD#PBF | 3x3 DFN-8 | I | $4.11 | $2.88 | Yes | |
| LT3505IDD#TRPBF | 3x3 DFN-8 | I | $2.94 | Yes | ||
| LT3505IMS8E#PBF | MS-8 | I | $4.40 | $3.08 | Yes | |
| LT3505IMS8E#TRPBF | MS-8 | I | $3.14 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Automotive Battery Regulation
- Industrial Control Supplies
- Wall Transformer Regulation
- Distributed Supply Regulation
- Battery-Powered Equipment
People Who Viewed This Product Also Viewed
- LT8610 - 42V, 2.5A Synchronous Step-Down Regulator with 2.5μA Quiescent Current
- LT3502/LT3502A - 1.1MHz/2.2MHz, 500mA Step-Down Regulators in 2mm × 2mm DFN and MS10
- LT3080 - Adjustable 1.1A Single Resistor Low Dropout Regulator
- LTC3646/LTC3646-1 - 40V, 1A Synchronous Step-Down Converter
- LT1763 - 500mA, Low Noise, LDO Micropower Regulators
- LT3580 - Boost/Inverting DC/DC Converter with 2A Switch, Soft-Start, and Synchronization
- LTC3115-1 - 40V, 2A Synchronous Buck-Boost DC/DC Converter
- LTC3789 - High Efficiency, Synchronous, 4-Switch Buck-Boost Controller
- LT1933 - 600mA, 500kHz Step-Down Switching Regulator in SOT-23
- LT1761 - 100mA, Low Noise, LDO Micropower Regulators in TSOT-23
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:
- Step 1: If you have not installed LTspice on this computer, download and install LTspice
- Step 2: Once LTspice is installed, click on the link(s) below to launch the simulation
- Step 3: If LTspice 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:
LT3505
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
Design tools for the following parts are available in LTpowerCAD:
LT3505
Technical Support
- For immediate technical assistance, contact your local sales office or distributor or call 1-800-4-LINEAR (US customers only) or 408-432-1900.
- For less urgent requests, please complete our Technical Support Request Form. Please allow 2-3 business days for reply.
