Analog Devices LTC3895EFE | Demoboard DC2117A

Description

Demonstration circuit 2117A is a single output high voltagenonisolated synchronous step-down converter thatdrives all N-channel MOSFET power stage. It features theLTC3895EFE, a high voltage step-down DC/DC controllerhoused in a TSSOP-38 package with several pins removedfor high voltage spacing.This DC2117A operates over an input voltage range from14V to 130V, while the LTC®3895 can operate up to 150V.This demo board produces a 12V output voltage with up toa 5A output current, and is configured with a sense resistorfor over current protection and has optional DCR sensing.To prevent high on-chip power dissipation in high inputvoltage applications, the LTC3895 includes an NDRV pinwhich drives the gate of an optional external N-channelMOSFET acting as a low dropout linear regulator to supplyIC power and is an option on this board.An internal charge pump allows for 100% duty cycle operationin dropout, a useful feature when powered froma battery during discharge. The LTC3895’s powerful 1ΩL, LT, LTC, LTM, Linear Technology, Burst Mode and the Linear logo are registered trademarksof Linear Technology Corporation. All other trademarks are the property of their respectiveowners.PERFORMANCE SUMMARYN-channel MOSFET gate drivers can be adjusted from5V to 10V to enable the use of logic- or standard-levelMOSFETs to maximize efficiency. The EXTVCC pin permitsthe LTC3895 to be powered from the output of the switchingregulator or other available source, reducing powerdissipation and improving efficiency.A mode selector allows the DC2117A to operate in forcedcontinuous operation, pulse-skipping or low rippleBurst Mode® operation during light loads. Additionalfeatures include a power good output signal, a PLLIN,PHASEMD and CLKOUT for multiphase operation.The LTC3895 data sheet gives a complete description ofthe part, operation and application information and mustbe read in conjunction with this demo board manual.

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