LTC1698 - Isolated Secondary Synchronous Rectifier Controller
Features
- High Efficiency Over Wide Load Current Range
- ±0.8% Output Voltage Accuracy
- Dual N-Channel MOSFET Synchronous Drivers
- Pulse Transformer Synchronization
- Optocoupler Feedback Driver
- Programmable Current Limit Protection
- ±5% Margin Output Voltage Adjustment
- Adjustable Overvoltage Fault Protection
- Power Good Flag
- Auxiliary 3.3V Logic Supply
- Available in 16-Lead SSOP and SO Packages
Typical Application
Description
The LTC1698 is a precision secondary-side forward converter controller that synchronously drives external N-channel MOSFETs. It is designed for use with the LT3781 primary-side synchronous forward converter controller to create a completely isolated power supply. The LT3781 synchronizes the LTC1698 through a small pulse transformer and the LTC1698 drives a feedback optocoupler to close the feedback loop. Output accuracy of ±0.8% and high efficiency over a wide range of load currents are obtained.
The LTC1698 provides accurate secondary-side current limit using an external current sense resistor. The input voltage at the MARGIN pin provides ±5% output voltage adjustment. A power good flag and overvoltage input are provided to ensure proper power supply conditions. An auxiliary 3.3V logic supply is included that supplies up to 10mA of output current.
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 |
|---|---|---|---|---|---|
| LTC1698EGN#PBF | SSOP-16 | GN | E | 05-08-1641 (GN16) | Yes |
| LTC1698EGN#TRPBF | SSOP-16 | GN | E | 05-08-1641 (GN16) | Yes |
| LTC1698ES#PBF | SO-16 | S | E | 05-08-1610 (S16) | Yes |
| LTC1698ES#TRPBF | SO-16 | S | E | 05-08-1610 (S16) | Yes |
| LTC1698IGN#PBF | SSOP-16 | GN | I | 05-08-1641 (GN16) | Yes |
| LTC1698IGN#TRPBF | SSOP-16 | GN | I | 05-08-1641 (GN16) | Yes |
| LTC1698IS#PBF | SO-16 | S | I | 05-08-1610 (S16) | Yes |
| LTC1698IS#TRPBF | SO-16 | S | I | 05-08-1610 (S16) | 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 | |
|---|---|---|---|---|---|---|
| LTC1698EGN#PBF | SSOP-16 | E | $6.27 | $5.30 | Yes | |
| LTC1698EGN#TRPBF | SSOP-16 | E | $5.36 | Yes | ||
| LTC1698ES#PBF | SO-16 | E | $6.33 | $5.35 | Yes | |
| LTC1698ES#TRPBF | SO-16 | E | $5.41 | Yes | ||
| LTC1698IGN#PBF | SSOP-16 | I | $6.92 | $5.85 | Yes | |
| LTC1698IGN#TRPBF | SSOP-16 | I | $5.91 | Yes | ||
| LTC1698IS#PBF | SO-16 | I | $6.98 | $5.90 | Yes | |
| LTC1698IS#TRPBF | SO-16 | I | $5.96 | 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 |
|---|---|---|---|
| DC479A | LT3781EG, LTC1698EGN, LT1783CS5 | Isolated Synchronous, Forward Converter, Vin=36V-72V, Vout=3.3V @ 15A | $75.00 | |
| DC617A | LT3781EG LTC1698EGN LT1783CS5 | Isolated Synchronous Forward Converter, +Vin = 36V - 72V, +Vout = 2.5V @ 20A, Quarter Brick footprint | $75.00 | |
| DC759A | LT1952EGN, LTC1698EGN | 48Vin to 5V at 20A Converter, +Vin = 36V - 72V, +Vout = +5V at 20A | $175.00 | |
| Buy Now | |||
Applications
- 48V Input Isolated DC/DC Converters
- Isolated Telecommunication Power Systems
- Distributed Power Step-Down Converters
- Industrial Control Systems
- Automotive and Heavy Equipment
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Design Tools
LTspice
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Models for the following parts are available in LTspice:
LTC1698
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.
