DC/DC controller targets point-of-load regulators
Linear Technology
LTC3865/-1 DC/DC controller
The LTC3865/-1 is dual-output synchronous step-down DC/DC controller for use in point-of-load regulators in medical, industrial, automotive, datacom, telecom and multifunction printers.
The controller, which offers 95 per cent efficiency, incorporates two-pin selectable VOUT programming, a feature that saves four precision feedback resistors.
The output voltages maintain tight +/-1 per cent accuracy, including initial set-point, a -40 to 125C operating temperature range and load/line regulation.
Nine selectable output voltages ranging from 0.6 to 5V are possible.
The 4.5 to 38V input voltage range encompasses a variety of applications, including most intermediate bus voltages and battery chemistries.
The strong on-board N-channel MOSFET driver enables the use of high-power external MOSFETs to produce output currents as high as 20A.
A constant-frequency current-mode architecture allows a selectable fixed or phase-lockable (PLL) switching frequency from 250 to 770kHz.
Power loss and supply noise are minimised by operating the stages 180deg out-of-phase.
Opti-loop compensation reduces the transient response and can be optimised over a range of output capacitance and ESR values, including all ceramic input and output capacitors.
Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for maximum efficiency or by using an optional sense resistor.
Current foldback limits MOSFET heat dissipation during short-circuit conditions.
In addition, the LTC3865/-1 has adjustable soft-start or tracking to control the output voltage start-up characteristics.
With capability up to 99 per cent duty cycle, the LTC3865/-1 has a very low drop-out voltage, which extends run times in battery-powered applications.
The LTC3865/-1 is offered in thermally enhanced 5 x 5mm QFN-32 and SSOP-38 packages.
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