The LT8310 from Linear Technology Corp. is a a primary-side synchronous forward controller. The LT8310 operates over an input voltage range of 6 V to 100 V, is targeted for power levels up to 200 W, and provides a drive signal for secondary-side synchronous rectification to improve efficiency. Output voltage regulation of ±8% can be attained without the use of an optocoupler. When an optocoupler is used, ±1.5% regulation can be realized. A programmable volt-second clamp provides a safeguard for transformer reset that prevents saturation and protects the MOSFET. This function optimizes the transformer and MOSFET, reducing solution size.
The LT8310 computes the duty cycle required to create a constant VOUT in open loop applications, thereby simplifying the design. In closed loop applications, the LT8310 limits maximum VOUT if the optocoupler path breaks open.
Additional features include programmable overcurrent protection, adjustable input undervoltage, overvoltage lockout and built-in thermal shutdown. The LT8310 has a programmable 100 kHz to 500 kHz operating switching frequency and can be synchronized to an external clock, enabling the use of a wide range of output inductor values and transformer sizes.
The LT8310 is available in a TSSOP-20 package with several pins removed for high voltage spacing. The LT8310 E- and I-grade versions operate from a -40 °C to 125 °C junction temperature. The LT8310 H grade is guaranteed to operate from a -40 °C to 150 °C operating junction temperature. The LT8310 MP grade is guaranteed to operate from -55 °C to 150 °C operating junction temperature. The 1,000-piece price starts at $2.99 each.