LT3740 - Wide Operating Range, Valley Mode, No RSENSE Synchronous Step-Down Controller
Features
- Wide VIN Range: 2.2V to 22V
- Internal Boost Provides 6V Gate Drive For VIN Down to 2.2V
- No Sensing Resistor Required
- Dual N-Channel MOSFET Synchronous Drive
- Valley Current Mode Control
- Optimized for High Step-Down Ratio
- Power Good Output Voltage Monitor
- 0.8V Reference
- Three Pin-Selected Current Limit Levels
- Constant Switching Frequency: 300kHz
- Programmable Soft-Start
- Output Voltage Tracking
- Available in 16-Pin 5mm × 3mm DFN
Typical Application
Description
The LT3740 is a synchronous step-down switching regulator controller that drives N-channel power MOSFET stages. The controller uses valley current mode architecture to achieve very low duty cycles with excellent transient response without requiring a sense resistor.
The LT3740 includes an internal step-up converter to provide a bias 7.8V higher than the input voltage for the drive. This enables the part to work from an input voltage as low as 2.2V.
The XREF pin is an external reference input that allows the user to override the internal 0.8V feedback reference with any lower value, allowing full control of the output voltage during operation, output voltage tracking or soft-start.
The LT3740 has three current limit levels that can be chosen by connecting the RANGE pin to ground, open, and input respectively.
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 |
|---|---|---|---|---|---|
| LT3740EDHC#PBF | 5x3 DFN-16 | DHC | E | 05-08-1706 | Yes |
| LT3740EDHC#TRPBF | 5x3 DFN-16 | DHC | E | 05-08-1706 | 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 | |
|---|---|---|---|---|---|---|
| LT3740EDHC#PBF | 5x3 DFN-16 | E | $2.96 | $1.95 | Yes | |
| LT3740EDHC#TRPBF | 5x3 DFN-16 | E | $2.01 | 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 |
|---|---|---|---|
| DC947A | LT3740EDHC Demo Board | $125.00 | |
| Buy Now | |||
Applications
- Notebook and Palmtop Computers, PDA
- Portable Instruments
- Distributed Power 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
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:
LT3740
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:
LT3740
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.
