Automotive Electronics

Synchronous Forward MOSFET Driver eliminates Signal Transformer

Linear Technology Corporation announces the LT8311, a high efficiency secondary-side MOSFET driver that operates without the need for primary control in an isolated synchronous forward converter. The LT8311’s unique preactive mode eliminates the need for a signal transformer for primary to secondary-side communication by sensing signals on the secondary side to control synchronous rectification. This mode reduces component count and solution size.

The LT8311 operates over a 3.7V to 30V input voltage range and is used with a primary-side IC, such as the LT3752/-1. The complete forward converter can operate with input voltages ranging from 6.5V up to 400V+ making it suited for a wide range of applications including hybrid/electric vehicle automotive requirements. Furthermore, the LT8311 combines a 10mA opto-driver and a feedback loop error amplifier to enable output voltage feedback from the secondary to the primary side.

The entire system provides fixed frequency peak current mode control that has excellent line/load regulation and fast transient response. Additional features include a 1.5% reference voltage, a power good monitor and programmable soft-start of the output voltage. The LT8311 is available in a TSSOP-20 package with several pins removed for high peak voltage spacing.

The LT8311 E- and I-grade versions operate from a -40 to 125 degrees C junction temperature. The LT8311 H grade is guaranteed to operate from a -40 to 150 degrees C operating junction temperature. The LT8311 MP grade is guaranteed to operate from -55 to 150 degrees C operating junction temperature. The 1,000-piece price starts at $3.06 each.

Linear Technology Corporation
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