LT3509 - Dual 36V, 700mA Step-Down Regulator
Features
- Two 700mA Switching Regulators with Internal Power Switches
- Wide 3.6V to 36V Operating Range
- Overvoltage Lockout Protects Circuit Through 60V Supply Transients
- Short-Circuit Robust
- Low Dropout Voltage: 95% Maximum Duty Cycle
- Adjustable 300kHz to 2.2MHz Switching Frequency Synchronizable Over the Full Range
- Uses Small Inductors and Ceramic Capacitors
- Integrated Boost Diodes
- Internal Compensation
- Thermally Enhanced 14-Lead (4mm × 3mm) DFN and 16 Lead MSOP Packages
AEC-Q100 data available for specific packages
Typical Application
Description
The LT3509 is a dual, current mode, step-down switching regulator, with internal power switches each capable of providing 700mA output current. This regulator provides a compact and robust solution for multi-rail systems in harsh environments. It incorporates several protection features including overvoltage lockout and cycle-by-cycle current limit. Thermal shutdown provides additional protection. The loop compensation components and the boost diodes are integrated on-chip. Switching frequency is set by a single external resistor. External synchronization is also possible. The high maximum switching frequency allows the use of small inductors and ceramic capacitors for low ripple. Constant frequency operation above the AM band avoids interference with radio reception, making the LT3509 well suited for automotive applications. Each regulator has an independent shutdown and soft-start control pin. When both converters are powered down, the common circuitry enters a low current shutdown state.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 |
|---|---|---|---|---|---|
| LT3509EDE#PBF | 4x3 DFN-14 | DE | E | 05-08-1708 | Yes |
| LT3509EDE#TRPBF | 4x3 DFN-14 | DE | E | 05-08-1708 | Yes |
| LT3509EMSE#PBF | MS-16E | MSE | E | 05-08-1667 | Yes |
| LT3509EMSE#TRPBF | MS-16E | MSE | E | 05-08-1667 | Yes |
| LT3509HMSE#PBF | MS-16E | MSE | H | 05-08-1667 | Yes |
| LT3509HMSE#TRPBF | MS-16E | MSE | H | 05-08-1667 | Yes |
| LT3509IDE#PBF | 4x3 DFN-14 | DE | I | 05-08-1708 | Yes |
| LT3509IDE#TRPBF | 4x3 DFN-14 | DE | I | 05-08-1708 | Yes |
| LT3509IMSE#PBF | MS-16E | MSE | I | 05-08-1667 | Yes |
| LT3509IMSE#TRPBF | MS-16E | MSE | I | 05-08-1667 | 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 | |
|---|---|---|---|---|---|---|
| LT3509EDE#PBF | 4x3 DFN-14 | E | $4.22 | $2.95 | Yes | |
| LT3509EDE#TRPBF | 4x3 DFN-14 | E | $3.01 | Yes | ||
| LT3509EMSE#PBF | MS-16E | E | $4.36 | $3.05 | Yes | |
| LT3509EMSE#TRPBF | MS-16E | E | $3.11 | Yes | ||
| LT3509HMSE#PBF | MS-16E | H | $5.37 | $3.76 | Yes | |
| LT3509HMSE#TRPBF | MS-16E | H | $5.37 | $3.82 | Yes | |
| LT3509IDE#PBF | 4x3 DFN-14 | I | $4.84 | $3.39 | Yes | |
| LT3509IDE#TRPBF | 4x3 DFN-14 | I | $3.45 | Yes | ||
| LT3509IMSE#PBF | MS-16E | I | $5.02 | $3.51 | Yes | |
| LT3509IMSE#TRPBF | MS-16E | I | $3.57 | 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 |
|---|---|---|---|
| DC1248A | LT3509EDE Demo Board | 6.5V ≤ VIN ≤ 36V (60V Transients), Vout1 = 5V @ 0.7A, Vout2 = 3.3V @ 0.7A | $125.00 | |
| 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 | |
|---|---|---|---|---|---|---|
| LT3509HMSE#PBF | MS-16E | H | $5.37 | $3.76 | Yes | |
| LT3509HMSE#TRPBF | MS-16E | H | $5.37 | $3.82 | Yes | |
| LT3509IDE#PBF | 4x3 DFN-14 | I | $4.84 | $3.39 | Yes | |
| LT3509IDE#TRPBF | 4x3 DFN-14 | I | $3.45 | Yes | ||
| LT3509IMSE#PBF | MS-16E | I | $5.02 | $3.51 | Yes | |
| LT3509IMSE#TRPBF | MS-16E | I | $3.57 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- Automotive Electronics
- Industrial Controls
- Wall Transformer Regulation
- Networking Devices
- CPU, DSP, or FPGA Power
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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
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:
LT3509
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:
LT3509
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.
