LTC3649 - 60V, 4A Synchronous Step-Down Regulator with Rail-to-Rail Programmable Output
Features
- Wide VIN Range: 3.1V to 60V
- Wide VOUT Range: 0V to (VIN – 0.5V)
- Single Resistor VOUT Programming
- Integrated 110mΩ Top N-Channel/50mΩ Bottom N-Channel MOSFETs
- 95% Efficiency with 12VIN and 5VOUT
- Regulated IQ: 440μA, Shutdown IQ: 18μA
- Accurate Current Monitoring (±4%) without Sense Resistor
- Accurate Resistor Programmable Frequency (300kHz to 3MHz) with ±50% Frequency Sync Range
- Accurate Programmable Output Current
- Input Voltage Regulation for MPPT Applications
- ±0.8% Output Voltage Accuracy
- Peak Current Mode Operation
- Programmable Wire Drop Compensation
- Burst Mode® Operation, Forced Continuous Mode
- Internal Compensation and Programmable Soft-Start
- Overtemperature Protection
- Available in Thermally Enhanced 28-Lead (4mm × 5mm) QFN and TSSOP Packages
Typical Application
Description
The LTC®3649 is a high efficiency 60V, 4A synchronous monolithic step-down regulator. The regulator features a single resistor programmable output voltage, internal compensation and high efficiencies over a wide VOUT range.
The step-down regulator operates from an input voltage range of 3.1V to 60V and provides an adjustable rail-to-rail output range from (VIN – 0.5V) to ground while delivering up to 4A of output current. The switching frequency is also adjusted with an external resistor. A user-selectable mode input is provided to allow the user to trade off ripple noise for efficiency at light loads; Burst Mode operation provides the highest efficiency at light loads, while forced continuous mode provides low output ripple. The MODE/ SYNC pin can also be used to allow the user to synchronize the switching frequency to an external clock.
The LTC3649 operates with a peak current mode architecture that allows for fast transient response with inherent cycle-to-cycle current limit protection. It also features programmable output current limit, current monitoring and input voltage regulation.
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 |
|---|---|---|---|---|---|
| LTC3649EFE#PBF | TSSOP-28 | FE | E | 05-08-1663 (EB) | Yes |
| LTC3649EFE#TRPBF | TSSOP-28 | FE | E | 05-08-1663 (EB) | Yes |
| LTC3649EUFD#PBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3649EUFD#TRPBF | 4x5 QFN-28 | UFD | E | 05-08-1712 | Yes |
| LTC3649IFE#PBF | TSSOP-28 | FE | I | 05-08-1663 (EB) | Yes |
| LTC3649IFE#TRPBF | TSSOP-28 | FE | I | 05-08-1663 (EB) | Yes |
| LTC3649IUFD#PBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | Yes |
| LTC3649IUFD#TRPBF | 4x5 QFN-28 | UFD | I | 05-08-1712 | 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 | |
|---|---|---|---|---|---|---|
| LTC3649EFE#PBF | TSSOP-28 | E | $8.43 | $5.90 | Yes | |
| LTC3649EFE#TRPBF | TSSOP-28 | E | $5.96 | Yes | ||
| LTC3649EUFD#PBF | 4x5 QFN-28 | E | $8.07 | $5.65 | Yes | |
| LTC3649EUFD#TRPBF | 4x5 QFN-28 | E | $5.71 | Yes | ||
| LTC3649IFE#PBF | TSSOP-28 | I | $9.70 | $6.79 | Yes | |
| LTC3649IFE#TRPBF | TSSOP-28 | I | $6.85 | Yes | ||
| LTC3649IUFD#PBF | 4x5 QFN-28 | I | $9.29 | $6.50 | Yes | |
| LTC3649IUFD#TRPBF | 4x5 QFN-28 | I | $6.56 | 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 |
|---|---|---|---|
| DC2113A | LTC3649 Demo Board | Sync Buck, 3.1V ≤ VIN ≤ 60V, Vout = 3.3V/5V @ 4A | $150.00 | |
| Buy Now | |||
Applications
- Industrial Applications
- Automotive Applications
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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
- LTC3649 Demo Circuit - High Voltage Monolothic Synchronous Buck Regulator (4-60V to 5V @ 4A)
- LTC3649 Demo Circuit - High Voltage Monolothic Synchronous Buck Regulator with Cable Drop Compensation (4-60V to 5V @ 4A)
- LTC3649 Demo Circuit - High Voltage Monolithic Synchronous Buck Regulator with Output Voltage Control (10-60V to 2.5-7.5V @ 4A)
- LTC3649 Demo Circuit - Hold-Up Circuit Using a Buck Regulator with Vin Boost Capabilities (5.5-60V to 5V @ 4A, 8V Hold-Up)
- 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:
LTC3649
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
To open the project file for this circuit:
- Step 1: If you have not installed LTpowerCAD on this computer, download and install LTpowerCAD
- Step 2: Once LTpowerCAD is installed, click on the link(s) below to open the project file
- Step 3: If LTpowerCAD does not automatically open after clicking the link above, you can open the project file by right clicking on the link and selecting "Save Target As." After saving the file to your computer, start LTpowerCAD and open the project file by selecting 'Open Project' from the 'File' menu
Design tools for the following parts are available in LTpowerCAD:
LTC3649
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.
