Analog Devices LTC3875EUJ | Demoboard DC2000A

Description

Demonstration circuits 2229A-A and 2229A-B feature the LTC®3877 in two high output current, high efficiency, VID programmed step-down converters with sub-mΩ DCR sensing. For both converters, the input voltage range is6V to 14V and the switching frequency is 400kHz. The DC2229A-A provides two outputs. VOUT1 is VID programmable from 0.6V to 1.23V and VOUT2 is set for 1.5V. Both rails have a maximum load current of 30A. TheDC2229A-B assembly is a four phase converter providing a VID programmable output of 0.6V to 1.23V with a maximum load current of 120A. Phases 1 and 2 are controlled by the LTC3877 and phases 3 and 4 are controlled by the LTC3874 slave controller.The demo board uses 0.25μH inductors with a DCR value of 0.325mΩ. The LTC3877 and LTC3874 employ a proprietary sub-mΩ DCR sensing architecture which enhances the signal to provide accurate control of the inductor current. The low DCR inductors, along with the use of low Qg/lowRDS(ON) discrete FETs and strong gate drivers provides high efficiency for high output current supplies. The full load efficiency is 90.3%, as seen on the 1.5V rail of the LTC3877 dual output converter (DC2229A-A assembly)with an input voltage of 12V Additional features of this demo board include: n Remote sensing n PLLIN and CLKOUT pinsn PGOOD, RUN and TK/SS pins n Optional resistors to tie two or more phases together n Optional footprints for BSG0811 dual channel MOSFETsn Optional NTC network on the ITEMP pin of the LTC3877 for less current limit variation over temperature n Dynamic load circuit.The demo board uses a high density, two-sided drop-in layout. The core components for each dual phase section consists of MOSFETs, inductors, ceramic CIN, ceramic COUT on the top layer and the control circuit on the bottom, resides in a 1.3" x 1.3" area of the board.The LTC3877 and LTC3874 data sheets provide a complete description of the IC operation and application information. These data sheets must be read in conjunction with the quick start guide.

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