LTC3408 - 1.5MHz, 600mA Synchronous Step-Down Regulator with Bypass Transistor
Features
- Dynamically Adjustable Output from 0.3V to 3.5V
- 600mA Output Current
- Internal 0.08 Ohm P-Channel MOSFET Bypass Transistor
- High Efficiency: Up to 96%
- 1.5MHz Constant Frequency Operation
- No Schottky Diode Required
- Low Dropout Operation: 100% Duty Cycle
- 2.5V to 5V Input Voltage Range
- Shutdown Mode Draws <1µA Supply Current
- Current Mode Operation for Excellent Line and Load Transient Response
- Overtemperature Protected
- Available in 8-Lead 3mm x 3mm DFN Package
Typical Application
Description
The LTC3408 is a high efficiency monolithic synchronous buck regulator optimized for WCDMA power amplifier applications. The output voltage can be dynamically programmed from 0.3V to 3.5V. At VOUT > 3.6V an internal 0.08Ω bypass P-channel MOSFET connects VOUT directly to VIN, eliminating power loss through the inductor.
The input voltage range is 2.5V to 5V making the LTC3408 ideally suited for single Li-Ion battery-powered applications. 100% duty cycle provides low dropout operation, extending battery life in portable systems.
Switching frequency is internally set at 1.5MHz, allowing the use of small surface mount inductors and capacitors. The internal synchronous switch increases efficiency and eliminates the need for an external Schottky diode.
The LTC3408 is available in a low profile (0.75mm) 8-lead 3mm × 3mm DFN package.
U.S. Patent Numbers: 5481178, 6580258, 6304066, 6127815, 6498466, 6611131
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 |
|---|---|---|---|---|---|
| LTC3408EDD#PBF | 3x3 DFN-8 | DD | E | 05-08-1698 | Yes |
| LTC3408EDD#TRPBF | 3x3 DFN-8 | DD | E | 05-08-1698 | 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 | |
|---|---|---|---|---|---|---|
| LTC3408EDD#PBF | 3x3 DFN-8 | E | $2.64 | $1.90 | Yes | |
| LTC3408EDD#TRPBF | 3x3 DFN-8 | E | $2.02 | 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 |
|---|---|---|---|
| DC645A | LTC3408EDD | WCDMA Cellular Phone Buck Regulator, VIN = 2.7V to 5.5V, VOUT = 600mA | Contact Factory | |
| Buy Now | |||
Applications
- WCDMA Cell Phone Power Amplifiers
- Wireless Modems
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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:
LTC3408
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.
