Linear Technology / Analog Devices Micropower Isolated Flyback Converters
Analog Devices LT8316 Micropower No-Opto Isolated Flyback Controller operates from inputs up to 600V and doesn’t require an optoisolator to regulate the output.
A typical flyback topology uses optocouplers to communicate output voltage information on the secondary side back to the primary side. This wastes power, increases size and cost, and performs poorly.
Analog Devices’ LT8316 uses a third transformer winding to sample the output voltage from the isolated flyback waveform when the secondary current is nearly zero. This approach eliminates the need for optocouplers, resulting in a smaller design, and the output voltage is easily programmed with two resistors.
The LT8316 can operate from a 16V to 600V input. An internal depletion FET charges the capacitor on the INTVCC pin to provide startup power, with no bleeder resistor or other components necessary. The LT8316 can also work at input voltages above 600V by placing a Zener diode in series with the VIN pin.
Quasi-resonant boundary mode operation eliminates parasitic resistive voltage drops. This provides improved load regulation, reduces the size of the transformer, and minimizes switching energy loss. The LT8316 automatically switches to discontinuous conduction mode at light loads to maintain high efficiency, and to low ripple burst mode at very light loads. The internal current regulation loop enables constant-current and constant-voltage regulation.
The LT8316 is packaged in a 20-pin TSSOP with 4 pins removed to meet high-voltage spacing requirements. It has a programmable current limit and soft-start functionality, and a 75µA quiescent current. Designers can use the DC2718A, DC2781A, and DC2793A demo boards to evaluate performance, with each highlighting the LT8316’s performance in different applications.
For more information on Analog Devices’ LT8316 Micropower No-Opto Isolated Flyback Controller and its demo boards, visit Mouser.com.
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