LTC3705 - 2-Switch Forward Controller and Gate Driver
Features
- High-Speed Top and Bottom Gate Drivers for
- 2-Switch Forward Converter
- On-Chip Rectifier and Self-Starting Architecture
- Eliminate Need for Separate Gate Drive Bias Supply
- Wide Input Voltage Supply Range: 18V to 80V
- Tolerant of 100V Input Voltage Transients
- Linear Regulator Controller for Fast Start-Up
- Precision UVLO with Adjustable Hysteresis
- Overcurrent Protection
- Volt-Second Limit Prevents Transformer Core Saturation
- Voltage Feedforward for Fast Transient Response
- Available in 16-Lead Narrow SSOP Package
Typical Application
Description
The LTC3705 is a controller for a 2-switch forward converter and includes on-chip bottom and top gate drivers that do not require external transformers. For secondary-side control, combine the LTC3705 with the LTC3706 PolyPhase® secondary-side synchronous forward controller to create a complete forward converter using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals across the isolation barrier through a tiny pulse transformer. The on-chip rectifier and the same pulse transformer provide gate drive bias power.Alternatively, the LTC3705 can be used as a standalone voltage mode controller in a primary-side control architecture with optoisolator feedback. Voltage feedforward provides excellent line regulation and transient response.
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 |
|---|---|---|---|---|---|
| LTC3705EGN#PBF | SSOP-16 | GN | E | 05-08-1641 (GN16) | Yes |
| LTC3705EGN#TRPBF | SSOP-16 | GN | E | 05-08-1641 (GN16) | Yes |
| LTC3705IGN#PBF | SSOP-16 | GN | I | 05-08-1641 (GN16) | Yes |
| LTC3705IGN#TRPBF | SSOP-16 | GN | I | 05-08-1641 (GN16) | 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 | |
|---|---|---|---|---|---|---|
| LTC3705EGN#PBF | SSOP-16 | E | $3.76 | $2.63 | Yes | |
| LTC3705EGN#TRPBF | SSOP-16 | E | $2.69 | Yes | ||
| LTC3705IGN#PBF | SSOP-16 | I | $4.03 | $2.89 | Yes | |
| LTC3705IGN#TRPBF | SSOP-16 | I | $2.95 | 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 |
|---|---|---|---|
| DC776A | LTC3705EGN/LTC3706EGN Demo Board | Forward Converter with Secondary Side Control, 36V ≤ VIN ≤72V, Vout = 1.5V @ 45A | $225.00 | |
| Buy Now | |||
Applications
- Isolated 48V Telecommunication Systems
- Internet Servers and Routers
- Distributed Power Step-Down Converters
- Automotive and Heavy Equipment
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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:
LTC3705
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.
