DC/DC Controller for Automotive Audio Amplifiers

The LTC3787 high-power two-phase single-output synchronous step-up DC/DC controller is suited for high-power automotive audio amplifiers, as well as industrial and medical applications. Replacing the boost diodes with high-efficiency N-channel MOSFETs, the solution eliminates 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 per cent efficiency.

The LTC3787's 135uA standby quiescent current can be configured for Burst Mode operation for certain applications. 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 1.2Ohm 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 75 to 850kHz or a selectable fixed frequency from 50 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.

The LTC3787 has adjustable soft-start, a power good output and maintains one per cent reference voltage accuracy over an operating junction temperature range of -40 to 125C. The LTC3787 is available in SSOP-28 and 4 x 5mm QFN-28 packages. The 1,000-piece price starts at USD4.12 (GBP2.52) each.

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