Features and Benefits
- Supports Self-Starting Secondary-Side Control
- Direct Flux Limit™ Guarantees No Saturation
- Active Clamp Drive with Delay Adjustment
- On-Chip Bridge Rectifier Eliminates Need for Separate Gate Drive Bias Supply
- Wide Input Supply Range: 8V and Up (Limited Only by External Components)
- Linear Regulator Controller for Fast Start-Up
- High Speed Gate Drivers
- Precision UVLO with Adjustable Hysteresis
- Overcurrent Protection
- Overtemperature Protection
- Adjustable Start-Up Frequency and Soft-Start
- Tiny 16-Lead MSOP Package
The LTC3765 is a start-up controller and gate driver for use in a self-starting secondary-side control forward converter. When combined with the LTC3766 secondary-side synchronous forward controller, a complete isolated power supply is created using a minimum of discrete parts. A proprietary scheme is used to multiplex gate drive signals and bias power across the isolation barrier through a small pulse transformer. The LTC3765 contains an onchip bridge rectifier that extracts gate drive bias power from this pulse transformer, eliminating the need for a separate bias supply. A precision undervoltage lockout circuit and linear regulator controller ensure a quick and well-controlled start-up.
The LTC3765 includes an active clamp output for driving an external PMOS, as well as an adjustable delay to optimize efficiency. The active clamp architecture reduces voltage stress on the main power switch, and provides the highest possible efficiency. Overcurrent protection and the Direct Flux Limit guarantee no transformer saturation without compromising transient response.
- Isolated Battery Chargers
- Isolated 48V Telecommunication Systems
- Servers and Embedded Computing
- Automotive and Heavy Equipment
Product Lifecycle Recommended for New Designs
This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.
Evaluation Kits (5)
Demonstration circuit 2199B-C is a 300W isolated forward converter with synchronous rectification featuring the LTC3765/LTC3766 chip-set. It produces a regulated 56V, 5.4A output from an input voltage range of 36V to 60V.
Demonstration circuit 2199A-B is a 360W isolated forward converter with synchronous rectification featuring the LTC3765/LTC3766 chip-set. It produces a regulated 24V, 15A output from an input voltage range of 36V to 60V.
Demonstration circuit 2199A-A is a 360W isolated forward converter with synchronous rectification featuring the LTC3765/LTC3766. It produces a regulated 12V, 30A output from an input voltage range of 36V to 60V.
Demonstration circuit 1739B-C is a 120W isolated forward converter with synchronous rectification featuring the LTC3765/LTC3766 chip set. This circuit demonstrates the high level of performance, efficiency, and small solution size attainable using this chipset in an active-clamp-reset forward converter power supply. It operates at 240kHz and produces a regulated 12V/10A output from an input voltage range of 9V to 36V. It has an eighth-brick footprint area.
Demonstration circuit 1739A-B is a 150W isolated forward converter with synchronous rectification featuring the LTC3765/LTC3766. This circuit demonstrates a high level of performance, efficiency, and small solution size attainable using these parts in an active-clamp-reset forward converter power supply. It operates at 240kHz and produces a regulated 12V, 12.5A output from an input voltage range of 18V to 72V, making it well suited for telecom, industrial, and other applications.
Tools & Simulations
LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.
To launch ready-to-run LTspice demonstration circuits for this part:
Step 1: Download and install LTspice on your computer.
Step 2: Click on the link in the section below to download a demonstration circuit.
Step 3: If LTspice does not automatically open after clicking the link below, you can instead run the simulation by right clicking on the link and selecting “Save Target As.” After saving the file to your computer, start LTspice and open the demonstration circuit by selecting ‘Open’ from the ‘File’ menu.
Models for the following parts are available in LTspice:
Product Selector Card (1)
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Sample & Buy
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