Linear Technology Corp. (LTC, Milpitas, CA) introduced the LT3804, a secondary-side, dc/dc regulator with an integrated optocoupler driver for dual-output, isolated power supplies. Unlike previous dual-output isolated power supplies that require up to two dc/dc regulators and an external optocoupler driver, the LT3804 is a single controller solution housed in a small, 28-lead, TSSOP package. The LT3804 is suitable for converting 36V to 72V supplies to output voltages of 5V, 3.3V, 2.5V, 1.8V, 1.5V and lower at up to 50W per output.
When combined with Linear Technology's primary-side, dc/dc regulators, the LT3804 offers a complete, isolated, dual-output power supply priced up to 40% below comparable dc/dc modules, according to the company. Applications include 48V distributed power, datacom/telecom, DSL/cable modems, servers and RAID systems, as well as industrial and automotive instruments.
The LT3804 contains an error amplifier and an optocoupler driver to regulate the main output. For the second output regulation, the integrated circuit contains a complete pulse-width modulated controller to drive dual-synchronous, n-channel MOSFETs. With leading-edge modulation, it operates with either current-mode or voltage-mode control of the primary side. The device is synchronized to the falling edge of the transformer secondary winding and can be used in single-ended or double-ended isolated power converter topologies. The LT3804 operates with switching frequencies ranging from 200kHz to 800kHz.
The LT3804 is rated for operation from -40°C to +125°C. The 1,000-piece price is $5.35 each.