Linear Technology Corp.'s H- and MP-grade versions of the LTC3890/-1 are high voltage dual output synchronous
step-down dc/dc controllers and draws 50µ when one output is active and 60µ
when both outputs are enabled. The 4 to 60V input supply range is designed to
protect against high voltage transients, continue operation during automotive
cold crank and cover a broad range of input sources and battery chemistries.
Each output can be set from 0.8 to 24V at output currents up to 20A with
efficiencies as high as 95 percent, making the LTC3890/-1 well suited for 12 or
24V automotive, heavy equipment, industrial control, robotics and telecom
applications. These H- and MP-grade versions are guaranteed over operating
junction temperatures from -40 to 150C and -55 to 150C, respectively.
The LTC3890/-1 has powerful on-chip 1.1Ohm MOSFET gate drivers. The device
operates with a selectable fixed frequency between and 900kHz, and can be
synchronized to an external clock from 75 to 850kHz with its phased-locked loop
(PLL). The user can select from continuous operation, pulse skipping and low ripple
Burst Mode operation during light loads. The LTC3890/-1's 2-phase operation
reduces input filtering and capacitance requirements. Its current mode
architecture provides easy loop compensation, fast transient response and
excellent line regulation. Output current sensing is accomplished by measuring
the voltage drop across the output inductor (DCR) for the highest efficiency or
by using an optional sense resistor.
This device is available in two versions. The LTC3890 is the fully featured
part in a 32-lead 5 x 5mm QFN package with functions including a clock out,
clock phase modulation, two separate power good outputs and adjustable current
limit. The LTC3890-1 is housed in a 28-pin SSOP package. The 1000-piece price
starts at $5.85 each for the H-grade devices and $15.80 each for the MP-grade
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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