Synchronous Forward MOSFET Driver Sheds Signal Transformer

The LT8311 secondary-side MOSFET driver operates without requiring primary control in an isolated synchronous forward converter. Developed by Linear Technology, the driver features a preactive mode that eliminates the need for a signal transformer for primary- to secondar-side communication—it senses signals on the secondary side to control synchronous rectification. The device, operating over a 3.7- to 30-V input voltage range, is used with a primary-side IC (e.g., the LT3752/1). The complete forward converter operates from 6.5 up to over 400 V input voltages. It combines a 10-mA opto-driver and feedback loop error amplifier, which enables output-voltage feedback from the secondary to primary side. The entire system offers fixed-frequency peak current-mode control with enhanced line/load regulation and transient response. Other features include a 1.5% reference voltage, power-good monitor, and programmable soft-start of the output voltage. Operating junction temperature ranges from ‒40 to 125°C (extended and industrial grade), ‒40 to 150°C (automotive grade), and ‒55 to 150°C (military grade). All come in TSSOP-20 packages with several pins removed for high peak voltage spacing.

LINEAR TECHNOLOGY CORP.