Features and Benefits
- 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
The LT8311 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.
- Offline and HV Car Battery Isolated Power Supplies
- 48V Isolated Power Supplies
- Industrial, Automotive and Military Systems
Product Lifecycle Production
At least one model within this product family is in production and available for purchase. The product is appropriate for new designs but newer alternatives may exist.
Evaluation Kits (4)
Demonstration circuit 1994A is an active clamp forward converter with synchronous rectification featuring the LT3752/LT8311 chipset. This circuit was designed to demonstrate the high levels of performance, efficiency, and small solution size attainable using these parts. It operates at 240kHz and produces a regulated 12V, 12A output from an input voltage range of 18 to 72V: suitable for telecom, industrial, and other applications. It has an eighth-brick footprint area. Synchronous rectification helps to attain efficiency exceeding 94%.
Demonstration circuit 2175A is an active clamp forward converter with synchronous rectification featuring the LT3752/LT8311 chipset.
This circuit was designed to demonstrate the high levels of performance, efficiency and high power. It operates at 200kHz and produces a regulated 12V, 13A output from a wide input voltage range of 9V to 36V, making it well suited for telecom, industrial, and other applications. Synchronous rectification helps to attain efficiency exceeding 93%.
Demonstration circuit 2015A is a resonant reset forward converter with synchronous rectification featuring the LT8310/LT8311 chipset. This circuit was designed to demonstrate the high levels of performance, efficiency, and small solution size attainable using these parts. It operates at 240kHz and produces a regulated 12V, 12A output from an input voltage range of 36V to 72V: suitable for telecom, industrial, and other applications. It has an eighth-brick footprint area. Synchronous rectification helps to attain efficiency exceeding 94%.
Demonstration circuit 1929A is a 200W active clamp forward converter featuring the LT3752-1/LT8311 chipset. The LT8311 is a secondary-side synchronous rectifier controller. The solution operates at about 100kHz and produces an isolated, regulated 12V / 16.7A output from an input voltage ranging from 150V to 400V, making it well suited for automotive, 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:
Solutions Bulletins & Brochures (1)
Press Releases (1)
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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.