Secondary Side Drivers

The LTC3900 and LTC3901 secondary side synchronous N-channel MOSFET drivers from Linear Technology Corp. both have timer and current sense comparators to protect the external MOSFETs during normal and light load operation, power up/down, and when the driver supply voltage drops too low. A programmable timeout function disables the synchronous drivers when the synchronization signal between the primary and secondary sides is missing or incorrect. This protects the MOSFETs from overvoltage and electrical overstress.

Additionally, the ICs turn off the MOSFETs if the negative inductor current exceeds a user-programmable level, thereby preventing the buildup of excessive inductor energy and possible damage. Moreover, to ensure proper power up and power down, these drivers shut off the MOSFETs when the driver input voltage is below 4V. The LTC3900 is designed for use in forward converter topologies, and the LTC3901 is suited for use in push-pull and full-bridge converters. Applications include 48-V input isolated dc-dc converters, isolated telecom power supplies, industrial control and automotive equipment.

For more information, visit www.linear.com.