LT8311 - Synchronous Rectifier Controller with Opto-Coupler Driver for Forward Converters
Features
- Wide Input Supply Range: 3.7V to 30V
- Preactive Mode:
- No Pulse Transformer Required
- DCM Operation at Light Load
- SYNC Mode:
- FCM or DCM Operation at Light Load
- Achieves Highest Efficiency
- 1.5% Feedback Voltage Reference
- 10mA Opto-Coupler Driver
- Output Power Good Indicator
- Integrated Soft-Start Function
Typical Application
Description
The LT®8311 is used on the secondary side of a forward converter to provide synchronous MOSFET control and output voltage feedback through an opto-coupler. The LT8311’s unique preactive mode allows control of the secondary-side MOSFETs without requiring a traditional pulse transformer for primary- to secondary-side communication. In preactive mode, the output inductor current operates in discontinuous conduction mode (DCM) at light load. If forced continuous mode (FCM) operation is desired at light load, the LT8311 can, alternatively, be used in SYNC mode, where a pulse transformer is required to send synchronous control signals from the primary-side IC to the LT8311.
The LT8311 offers a full featured opto-coupler controller, incorporating a 1.5% reference, a transconductance error amplifier and a 10mA opto-driver. Power good monitoring and output soft-start/overshoot control are also included. The LT8311 is available in a 16-lead FE package with pins removed for high voltage spacing requirements.
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 |
|---|---|---|---|---|---|
| LT8311EFE#PBF | TSSOP-20 | FE | E | 05-08-1924 | Yes |
| LT8311EFE#TRPBF | TSSOP-20 | FE | E | 05-08-1924 | Yes |
| LT8311HFE#PBF | TSSOP-20 | FE | H | 05-08-1924 | Yes |
| LT8311HFE#TRPBF | TSSOP-20 | FE | H | 05-08-1924 | Yes |
| LT8311IFE#PBF | TSSOP-20 | FE | I | 05-08-1924 | Yes |
| LT8311IFE#TRPBF | TSSOP-20 | FE | I | 05-08-1924 | Yes |
| LT8311MPFE#PBF | TSSOP-20 | FE | MP | 05-08-1924 | Yes |
| LT8311MPFE#TRPBF | TSSOP-20 | FE | MP | 05-08-1924 | 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 | |
|---|---|---|---|---|---|---|
| LT8311EFE#PBF | TSSOP-20 | E | $4.37 | $3.06 | Yes | |
| LT8311EFE#TRPBF | TSSOP-20 | E | $3.12 | Yes | ||
| LT8311HFE#PBF | TSSOP-20 | H | $5.22 | $3.65 | Yes | |
| LT8311HFE#TRPBF | TSSOP-20 | H | $3.71 | Yes | ||
| LT8311IFE#PBF | TSSOP-20 | I | $4.79 | $3.35 | Yes | |
| LT8311IFE#TRPBF | TSSOP-20 | I | $3.41 | Yes | ||
| LT8311MPFE#PBF | TSSOP-20 | MP | $12.94 | $9.06 | Yes | |
| LT8311MPFE#TRPBF | TSSOP-20 | MP | $9.12 | 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 |
|---|---|---|---|
| DC1929A | LT3752EFE-1/ LT8311EFE Demo Board | 150V ≤ VIN ≤ 400V, VOUT = 12V @ 16.7A | $300.00 | |
| DC1994A | LT3752EFE/LT8311EFE Isolated Demo Board | 18V ≤ VIN ≤ 72V; VOUT: 12V @ 12A | $300.00 | |
| DC2015A | LT8310EFE/LT8311EFE Isolated Demo Board | 36V ≤ VIN ≤ 72V; VOUT = 12V @ 12A | $300.00 | |
| DC2175A | LT3752IFE/LT8311IFE Demo Board | Forward Converter with Sync Rectification, 9V ≤ VIN ≤ 36V; Vout = 12V @ 13A | $300.00 | |
| Buy Now | |||
Applications
- Offline and HV Car Battery Isolated Power Supplies
- 48V Isolated Power Supplies
- Industrial, Automotive and Military Systems
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Design Tools
LTspice
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LT8311
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.
