Power Electronics

Multiphase Stepdown Controller Provides PLL and Output Tracking

Linear Technology has introduced the LTC3828, a dual-stepdown synchronous switching controller with integrated tracking for sequencing multiple voltage rails, phase-locked loop (PLL) for precision synchronization and PolyPhase operation for reducing input capacitance. The LTC3828 has a unique capability to daisy chain to multiple LTC3828s or other dc-dc converters to provide tracking for more than two voltages while operating at three, four or six phases. The IC has a constant 550-kHz current-mode architecture and also can be locked to a 260-kHz to 550-kHz clock to reduce EMI at sensitive frequencies.

The LTC3828 is used to convert a 4.5-V to 28-V (30-V max) input voltage to two regulated output voltages, adjustable from 0.8 V to as high as 99% of the value of the input voltage. The LTC3828’s wide operating voltage and unique integrated functions enable the design of compact multiple output power supplies in applications such as single-board computers, industrial equipment, automotive electronics and FPGA-based systems.

The LTC3828 uses a constant frequency, current-mode all N-channel MOSFET synchronous architecture with the two control channels operating 180 degrees out of phase. A clock output pin enables synchronization of multiple controllers. The IC allows the user to program how the channel outputs ramp up and down. Both coincident and ratiometric tracking are supported. Moreover, high current gate drivers allow high power density solutions. Powering difficult loads such as starting with pre-biased outputs, common when powering ASICS, is supported by preventing reverse inductor currents and disabling current fold back during start-up.

The LTC3828 is offered in 28-lead SSOP and 5-mm × 5-mm QFN packages. In quantities of 1000, pricing starts at $4.65 each.

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