Linear Tech High Power Polyphase Synchronous Boost Controller Eliminates Heat Sink with 97% Efficiency
Linear Technology Corp. announced the LTC3787, a high power two phase single output synchronous step-up dc-dc controller, which replaces the boost diodes with high efficiency N-channel MOSFETs. This solution is said to eliminate the heat sink normally required in medium to high power boost converters. The LTC3787 can produce a 24V at 10A output from a 12V input at up to 97% efficiency. The LTC3787’s 135µA standby quiescent current when configured for Burst Mode® operation makes it well suited for high power automotive audio amplifiers, as well as industrial and medical applications where a step-up dc-dc converter must deliver high power in a small solution size.
The LTC3787 operates from an input voltage ranging from 4.5 to 38V during start-up, maintains operation down to 2.5V after start-up and can regulate an output voltage as high as 60V. The powerful 1.2Ω onboard N-channel MOSFET gate drivers are capable of slewing large MOSFET gates quickly. The device’s current mode architecture, clock output and phase modulation enables easy paralleling of multiple devices for up to 12 phase operation. The LTC3787 has a phase-lockable frequency from 75kHz to 850kHz or a selectable fixed frequency from 50kHz to 900kHz. In applications where the input voltage exceeds the regulated output voltage, the LTC3787 keeps the synchronous MOSFET on continuously so that the output voltage follows the input voltage with minimal power loss. In addition, this device features adjustable cycle-by-cycle current limit and can use a sense resistor or monitor the voltage drop across the inductor (DCR) for current sensing. Furthermore, the LTC3787 has adjustable soft-start, a power good output and maintains +1% reference voltage accuracy over an operating junction temperature range of -40 to 125°C.
The LTC3787 is available in SSOP-28 and 4 x 5mm QFN-28 packages. The 1,000-piece price starts at $4.12 each.
