DEMO MANUAL DC2002A LTC3774EUHE High Efficiency Dual Output Step-Down Converter with Very Low DCR Inductor Description Demonstration circuit DC2002A is a dual output synchro- Additional features of this demo board include: nous buck converter featuring the LTC3774EUHE. The Remote Sensing for Each Output demo board supplies two rails of 1.5V / 30A and 1.2V / 30A. PLLIN and CLKOUT Pins The power stage for each rail consists of a 0.33H 0.32m PGOOD, RUN and TRK/SS Pins for Each Output DCR inductor with a 11mm 11mm footprint and a 6mm 6mm DrMOS driven by the PWM outputs of the Optional Resistors to Tie the Two Outputs Together LTC3774EUHE at a switching frequency of 400kHz. The Optional Footprint for Hot Swap FET on the Input of inductor, DrMOS and the local ceramic input and output Each Phase for MOSFET Failure Protection capacitors forms the core converter which occupies a 1.1 1.1 area on the top layer. The control circuit is Optional Footprint for an LTC4449 Gate Driver and directly underneath on the bottom layer and occupies an Discrete MOSFETs area of 0.9 1.1. The result is a two sided core converter Optional Footprint for a Dual Phase Delta Power Block with a current density of 50A per square inch and a full load efficiency of 91.1% for the 1.5V rail and 90.0% for Design files for this circuit board are available at the 1.2V rail. DEMO MANUAL DC2002A Quick s Dp Demonstration circuit 2002A is easy to set up to evaluate 3. Connect the output of the pulse generator to the PULSE the performance of the LTC3774EUHE. Please refer to GEN turret for the rail under test and connect the return Figure 1 for proper measurement equipment setup and to the adjacent GND turret. follow the procedure below. 4. With the converter running, slowly increase the am- 1. With power off, connect the input supply, load and plitude of the pulse generator output to provide the meters as shown in Figure 1. Preset the load to 0A desired load step pulse height. The scaling for the load and V supply to be 0V. For both assemblies, place step signal is 5mV/Amp. IN the jumpers in the following positions: Single Output/Dual Phase Operation JP1 RUN1 ON A single output/dual phase converter may be preferred for JP2 RUN2 ON higher output current applications. The optional compo- JP5 MODE CCM nents required to tie the phases together are found on the lower left of the 1st sheet. To tie the two outputs together, 2. Adjust the input voltage to be between 7V and 14V. make the following modifications: V should be 1.5V 2%. OUT1 1. Tie the two V shapes together with a piece of copper OUT V should be 1.2V 2%. OUT2 or a 0m jumper at R47 and R36. One part to consider 3. Next, apply 30A load to each output and re-measure is Tepro RN5326. V . OUT 2. Tie V to V by stuffing a 0 resistor at R53 OSNS1 OSNS2 4. Once the DC regulation is confirmed, observe the output and tie V to V by stuffing a 0 resistor at R92. OS1 OS2 voltage ripple, load step response, efficiency and other 3. Tie ITH1 to ITH2 by stuffing a 0 resistor at R68. parameters. 4. Tie RUN1 to RUN2 by stuffing a 0 resistor at R54. Note 1. Use the BNC connectors labeled V or V OUT1 OUT2 to measure the output voltage ripple. 5. Tie TK/SS1 to TK/SS2 by stuffing a 0 resistor at R48. + Note 2. Do not connect load from the V turret to the OS1 Paralleling Boards + V turret or from the V turret to the V tur- OS1 OS2 OS2 Up to 6 DC2002A demo boards can be paralleled to ret. This could damage the converter. Only apply load produce a single output, 12 phase converter. To connect across the stud connectors on the edge of the board. two or more DC2002A boards together, first tie the two Dynamic Load Circuit (Optional) phases together as described in the Single Output/Dual Phase Operation section. Next, place the boards side by Demonstration circuit 2002A provides a simple load step side such that header J8 of one board mates with socket circuit consisting of a MOSFET and sense resistor for each J9 of the other. This will connect the common control rail. To apply a load step, follow the steps below. signals together which are the V , V , ITH, RUN OSNS OS 1. Pre-set the amplitude of a pulse generator to 0.0V and and TK/SS signals. It will also tie the CLKOUT signal of the duty cycle to 5% or less. one phase to the PLLIN input of the other phase. Next, tie the V , V and GND of the boards together using OUT IN 2. Connect the scope to the V /V BNC connectors OUT1 OUT2 the exposed copper on the edges of the board. Figure 6 for the rail under test with a coax cable. To monitor the shows how to tie 2 boards together for a single output, load step current, connect the scope probe across the 4 phase converter. ISTEP turrets for that rail. dc2002af 2 ure roce tart