LTC1773 - Synchronous Step-Down DC/DC Controller
Features
- High Efficiency: Up to 95%
- Constant Frequency 550kHz Operation
- VIN from 2.65V to 8.5V
- VOUT from 0.8V to VIN
- OPTI-LOOP™ Compensation Minimizes COUT
- Synchronizable up to 750kHz
- Selectable Burst Mode Operation
- Low Quiescent Current: 80µA
- Low Dropout Operation: 100% Duty Cycle
- Secondary Winding Regulation
- Soft-Start
- Current Mode Operation for Excellent Line and Load Transient Response
- Low Quiescent Current: 80µA
- Low Shutdown IQ = 10µA
- ±1.5% Reference Accuracy
- Precision 2.5V Undervoltage Lockout
- Available in 10-Lead MSOP
Typical Application
Description
The LTC1773 is a current mode synchronous buck regulator controller that drives external complementary power MOSFETs using a fixed frequency architecture. The operating supply range is from 2.65V to 8.5V, making it suitable for 1- or 2-cell lithium-ion battery powered applications. Burst Mode operation provides high efficiency at low load currents. 100% duty cycle provides low dropout operation which extends operating time in battery-operated systems.
The operating frequency is internally set at 550kHz, allowing the use of small surface mount inductors. For switching-noise sensitive applications, it can be synchronized up to 750kHz. Peak current limit is user programmable with an external high side sense resistor. A SYNC/FCB control pin guarantees regulation of secondary windings regardless of load on the main output by forcing continuous operation. Burst Mode operation is inhibited during synchronization or when the SYNC/FCB pin is pulled low to reduce noise and RF interference. Soft-start is provided by an external capacitor.
Synchronous rectification increases efficiency and eliminates the need for a Schottky diode, saving components and board space. The LTC1773 comes in a 10-lead MSOP package.
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 |
|---|---|---|---|---|---|
| LTC1773EMS#PBF | MS-10 | MS | E | 05-08-1661 | Yes |
| LTC1773EMS#TRPBF | MS-10 | MS | E | 05-08-1661 | 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 | |
|---|---|---|---|---|---|---|
| LTC1773EMS#PBF | MS-10 | E | $2.90 | $2.50 | Yes | |
| LTC1773EMS#TRPBF | MS-10 | E | $2.56 | 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 |
|---|---|---|---|
| DC309A | LTC1773EMS | 3A Synchronous Buck Regulator, 2.8V to 8.5V Input, 1.5V/1.8V/2.5V/3.3V @ 2.5A avg / 3A peak | $100.00 | |
| DC431A | LT1725CGN LTC1773EMS | Telecom Input, Isolated 3 Output DC/DC Converter, +36V to +72V Input, Vout = 5V/1A, 3.3V/5A, 2.5V/4A | Contact Factory | |
| Buy Now | |||
Applications
- Cellular Telephones
- RF PA Supply
- Portable Instruments
- Wireless MODEMS
- Distributed Power Systems
- Notebook and Palm Top Computers, PDAs
- Single and Dual Cell Lithium-Ion Powered Devices
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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
Models for the following parts are available in LTspice:
LTC1773
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.
