Technology Corp.'s LTC3789 is a high efficiency,
up to 98 percent, synchronous buck-boost dc/dc controller that operates from
input voltages above, below or equal to the regulated output voltage. High
power circuits that step-up and-down typically rely on transformers or two
dc/dc converters, one for step-up (boost) and the other for step-down (buck)
conversion. The LTC3789 operates using a single inductor with 4-switch
synchronous rectification and can deliver output power up to 150W with a single
device. Even higher output power can be achieved when multiple circuits are
The LTC3789 operates with a selectable fixed frequency between 200 and 600 kHz,
and can be synchronized to an external clock over the same range with its
integrated phase-locked loop (PLL). Its wide 4 to 38V input range, 0.8 to 38V
output range and seamless transitions between operating modes make it ideal for
a wide range of industrial controls, automotive, solar and high power
The LTC3789 employs a proprietary current-mode
control architecture for constant frequency operation in buck or boost mode and
has powerful onboard quad N-channel MOSFET gate drivers. The LTC3789 also
provides an accurate, constant-current regulation loop for either input or
output current, over a wide input voltage range. The input current limit
function prevents overloading of the input source, and the output current limit
provides an easy solution for regulated output current applications such as
battery charger or LED drivers. Fault protection is provided for overvoltage,
overcurrent and short circuit conditions in all operating modes. In addition,
the LTC3789 disconnects the input voltage from the output when in shutdown. The
user can select continuous or pulse skip mode to maximize light load
efficiency. The LTC3789 has adjustable soft-start, a power good output and
maintains Â±1.5 percent reference voltage accuracy over an operating junction
temperature range of -40 to 125C.
The LTC3789 is available in 28-pin 4 x 5mm QFN and 28-lead SSOP packages.
Pricing starts at $4.65 each in 1,000-piece quantities.
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