100-V forward converter outputs regulated 12 V without optocoupling

Linear Technology Corporation announces the LT8310, a primary-side synchronous forward controller. The LT8310 operates over an input voltage range of 6V to 100V, is targeted for power levels up to 200W 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 opto-coupler. When an opto-coupler 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 opto-coupler path breaks open.

Additional features include programmable overcurrent protection, adjustable input undervoltage, overvoltage lockout and built-in thermal shutdown. The LT8310 has a programmable 100kHz to 500kHz 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. For more information, visit www.linear.com/product/LT8310

Summary of Features: LT8310

• Wide VIN Range: 6V to 100V
• Programmable Volt-Second Clamp
• No Opto-Coupler Required
• High Efficiency Synchronous Rectification
• Short-Circuit Protection
• Selectable Fixed Operating Frequency from 100kHz to 500kHz
• Synchronizable to External Clock
• Programmable OVLO & UVLO with Hysteresis
• Extended & Industrial Grades: –40°C to 125°C Operating Junction Temp
• Automotive Temp Grade: –40°C to 150°C Operating Junction Temp
• Military Temp Grade: –55°C to 150°C Operating Junction Temp

Linear Technology Corporation
www.linear.com