DC/DC Transformer Driver with Programmable Duty Cycle Control

Sept26_LinearLinear Technology Corp. has announced the LT3999, a monolithic push-pull isolated DC/DC transformer driver with two 1A current limited power switches. The LT3999 operates over an input voltage range of 2.7 V to 36 V, is targeted for power levels up to 15 W and can produce a wide range of output voltages. This makes it well suited for automotive, industrial, medical and military applications.

The programmable duty cycle and turns ratio of the transformer sets the output voltage. Several off-the-shelf transformers shown in the data sheet simplify the design. The switching frequency is adjustable from 50 kHz to 1 MHz and can be synchronized to an external clock. The LT3999 input operating voltage range is set with the precise undervoltage and overvoltage lockouts. The supply current is reduced to less than 1 µA during shutdown. A user-defined RC time constant provides an adjustable soft-start capability by limiting the inrush current at start-up and an onboard cross-conduction prevention circuit increases reliability.

The LT3999 is available in thermally enhanced MSOP-10 and 3 mm by 3 mm DFN-10 packages. The LT3999 E- and I-grade versions operate from a -40°C to 125°C junction temperature. The LT3999 H grade is guaranteed to operate from a -40°C to 150°C operating junction temperature. The LT3999 MP grade is guaranteed to operate from -55°C to 150°C operating junction temperature. Devices are in stock, and the 1,000-piece price starts at $2.75 each for the E-grade.

For more information, visit www.linear.com/product/LT3999.