Arrow Plastic Network Card manual Triple Output, Multiphase, Synchronous Step-Down Controller

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Triple Output, Multiphase, Synchronous Step-Down Controller

Highly efficient, switching step-down DC/DC controller has numerous features

The LTC3853 is a highly efficient, synchronous step-down switching regulator, DC/DC controller with three outputs and numerous features that include output voltage tracking, Burst Mode® operation and pulse skipping, which safely powers pre-biased loads.

The latest device in Linear Technology’s next generation of step- down controllers, the LTC3853, complements the LTC3850 dual output and LTC3851 single output controllers. It has a 4.5V to 24V (28Vmax) input voltage range and can be powered from most intermediate bus voltages and battery chemistries.

The illustration shows a simplified schematic and the package of the LTC3853 step-down DC/DC converter. Strong onboard gate drivers power all N-channel MOSFET stages. Each stage can produce output currents up to 20A per channel with output voltages ranging from 0.8V to 13.5V on one channel and from 0.8V to 5.5V on the other two channels, making it ideal for point of load regulator requirements in medical, datacom, telecom, industrial, automotive applications, displays and set top boxes.

Its constant frequency, current-mode architecture provides a selectable fixed or synchronisable frequency from 250kHz to 750kHz using Phase Lock Loop (PLL). Operating the three channels 120º out of phase minimises power loss and supply noise. The LTC3853 can also be configured with one output channel 180º out of phase from channels two and three. True current-mode control enables stable operation over a wide range of output capacitance and ESR values, including all ceramic capacitors for the smallest solution size. It has current foldback to limit MOSFET heat dissipation during short circuit and overload conditions.

Additionally, the LTC3853 can be configured with DCR (inductor) current sensing to maximise efficiency and has a minimum on time of only 90ns for applications requiring high step-down ratios. An onboard regulator develops its own internal IC bias voltage and an adjustable soft-start controls the turn-on time. A precision 0.8V reference has ±1% accuracy over a -40ºC to +125ºC operating temperature range.

With up to 98% duty cycle, the LTC3853 has a very low dropout voltage, a useful feature for extending run times in battery powered applications.

The LTC3853 is offered in a thermally enhanced 6mm x 6mm QFN-40 package.

Features

UOnboard 5V linear bias voltage regulator

USafely powers pre-biased loads

UOutput voltage tracking

UBurst mode operation

UPulse skipping

UInput voltage range: 4.5V to 24V, 28Vmax

UOutput current: <20A per channel

UPowerful onboard MOSFET gate drivers

UOutput voltage: 0.8V to 13.5V on one channel, 0.8V to 5.5V on two channels

U<98% duty cycle

UOperating temperature range: -40ºC to +125ºC with ±1% reference voltage accuracy

UFixed or synchronisable operating frequency from 250kHz to 750kHz using PLL

UQFN-40, 6mm x 6mm package

Applications

UPoint of load regulators

UMedical

UData and telecom

UIndustrial

UAutomotive

UDisplays

USet top boxes

Linear

Technology

LTC3853

Datasheet

available!

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Arrow in Denmark,

Norway, Sweden,

UK and Ireland

For further information, including the LTC3853 Datasheet, please complete the reply slip or visit http://www.arrowne.com/innov/in218/f_1455.shtml

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