LT3845A - High Voltage Synchronous Current Mode Step-Down Controller with Adjustable Operating Frequency
Features
- High Voltage Operation: Up to 60V
- Synchronizable Up to 600kHz
- Adjustable Constant Frequency: 100kHz to 500kHz
- Output Voltages Up to 36V
- Stable Operation in Current Limit
- Adaptive Nonoverlap Circuitry Prevents Switch Shoot-Through
- Reverse Inductor Current Inhibit for Discontinuous Operation Improves Efficiency with Light Loads
- Programmable Soft-Start
- 120μA No Load Quiescent Current
- 10μA Shutdown Supply Current
- 1% Regulation Accuracy
- Standard Gate N-Channel Power MOSFETs
- Reverse Overcurrent Protection
- 16-Lead Thermally Enhanced TSSOP Package
AEC-Q100 data available for specific packages
Typical Application
Description
The LT3845A is a high voltage, synchronous, current mode controller used for medium to high power, high efficiency supplies. It offers a wide 4V to 60V input range (7.5V minimum start-up voltage). An onboard regulator simplifies the biasing requirements by providing IC power directly from VIN.
Burst Mode® operation maintains high efficiency at light loads by reducing IC quiescent current to 120μA. Light load efficiency is also improved with the reverse inductor current inhibit function which supports discontinuous operation.
Additional features include adjustable fixed operating frequency that can be synchronized to an external clock for noise sensitive applications, gate drivers capable of driving large N-channel MOSFETs, a precision undervoltage lockout, 10μA shutdown current, short-circuit protection and a programmable soft-start.
The LT3845A is available in a 16-lead thermally enhanced TSSOP package.
| Features | |
| LT3845 | - |
| LT3845A | Improved Performance In Over Current Conditions |
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 |
|---|---|---|---|---|---|
| LT3845AEFE#PBF | TSSOP-16 | FE | E | 05-08-1663 (BC) | Yes |
| LT3845AEFE#TRPBF | TSSOP-16 | FE | E | 05-08-1663 (BC) | Yes |
| LT3845AIFE#PBF | TSSOP-16 | FE | I | 05-08-1663 (BC) | Yes |
| LT3845AIFE#TRPBF | TSSOP-16 | FE | I | 05-08-1663 (BC) | Yes |
| LT3845AMPFE#PBF | TSSOP-16 | FE | MP | 05-08-1663 (BC) | Yes |
| LT3845AMPFE#TRPBF | TSSOP-16 | FE | MP | 05-08-1663 (BC) | 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 | |
|---|---|---|---|---|---|---|
| LT3845AEFE#PBF | TSSOP-16 | E | $5.09 | $3.56 | Yes | |
| LT3845AEFE#TRPBF | TSSOP-16 | E | $3.62 | Yes | ||
| LT3845AIFE#PBF | TSSOP-16 | I | $5.89 | $4.12 | Yes | |
| LT3845AIFE#TRPBF | TSSOP-16 | I | $4.18 | Yes | ||
| LT3845AMPFE#PBF | TSSOP-16 | MP | $15.22 | $10.65 | Yes | |
| LT3845AMPFE#TRPBF | TSSOP-16 | MP | $10.71 | 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 |
|---|---|---|---|
| DC1619A | LT3845AEFE Demo Board | 16V ≤ VIN ≤ 60V, VOUT = 12V @ 10A | $150.00 | |
| 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 | |
|---|---|---|---|---|---|---|
| LT3845AIFE#PBF | TSSOP-16 | I | $5.89 | $4.12 | Yes | |
| LT3845AIFE#TRPBF | TSSOP-16 | I | $4.18 | Yes | ||
| LT3845AMPFE#PBF | TSSOP-16 | MP | $15.22 | $10.65 | Yes | |
| LT3845AMPFE#TRPBF | TSSOP-16 | MP | $10.71 | Yes | ||
| Buy Now • Request Samples | ||||||
Applications
- 12V and 42V Automotive and Heavy Equipment
- 48V Telecom Power Supplies
- Avionics and Industrial Control Systems
- Distributed Power Converters
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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:
LT3845
LT3845A
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:
LT3845
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.
