Designed to protect against high voltage transients and continuing operation during automotive cold crank, the LT3840 is a synchronous, step-down DC/DC controller from Linear Technology. It is suitable for applications including 12 or 24V automotive, heavy equipment, industrial control, robotics and telecomms.
The DC/DC controller includes a 7.5V buck-boost bias voltage to provide efficient gate drive from a wide input range of 2.5-60V. It also generates a 7.5V bias voltage for MOSFET gate drive, regardless of the input voltage. The LT3840 extends run time in battery-powered applications with low power consumption of just 75µA when regulating the output voltage with no load.
The output voltage is configurable from 1.25-60V at up to 30A, delivering 95% efficiency. The controller is flexible, allowing users to select from continuous operation, pulse skipping and low ripple Burst Mode operation during light loads. A programmable current limit ensures accurate current regulation, while the current monitor function reports the average output current.
The LT3840 operates with a selectable fixed frequency in the 50kHz-1MHz range. Additionally, it can be synchronised to an external clock over the same range. The DC/DC controller also features powerful on-chip gate drivers to drive multiple standard or logic level N-channel MOSFETs. It offers easy loop compensation, fast transient response and excellent line regulation because of a current-mode architecture. The step-down controller provides up to 99% duty cycle for low voltage dropout, accurate over-and undervoltage lockouts, soft-start/tracking and a power good signal.
Supplied in 28-lead TSSOP and 4x6mm QFN-38 thermally enhanced packages, the LT3840 is available in extended, industrial, high temperature automotive grade and military grade versions. The extended and industrial versions operate from -40 to +125°C, the automotive operates version from -40 to +150°C and the military version from -55 to +150°C. Prices start from $3.65 (USD) each in 1,000 unit quantities.