DEMO MANUAL DC2354A LTC7149 60V, Low IQ High Voltage, Negative Output Monolithic Synchronous Regulator DESCRIPTION Demonstration circuit 2354A is a high input voltage, The DC2354A consumes less than 15A of quiescent cur- high efficiency synchronous monolithic step-down con- rent during shutdown and it consumes less than 600A verter with negative output featuring the LTC7149. The at no-load conditions in Burst Mode of operation. The DC2354A has wide input voltage range from 3.5V up to DC2354A has a standard operating frequency of 500kHz, 55V. Theoutput voltage of the DC2354A can be set as to but can be adjusted in a range between 300kHz and as 3.3V or 5V and User Select option of DC2354A allows high as 3MHz. LTC7149, which is used in DC2354A, inte- output voltage to be in a rage from 0V to 60V. However grates top and bottom N-Channel MOSFETs, significantly voltage difference between user-selected negative output reducing overall circuit footprint. DC2354A was designed voltage(V ) and maximum input voltage (V ), should to support multiple footprints of input/output capacitors OUT IN not exceed 60V. V + V < 60V. DC2354A is capable and inductors to accommodate variety of applications. OUT IN of delivering up to 4A of output current, nevertheless at The data sheet of LTC7149 gives a complete description lower input voltage load current should be reduced in functionality of this regulator also contains operation and accordance to enclosed derating curves. DC2354A sup- application information and must be read in conjunction ports three operation modes: Fixed-frequency modulation, with this manual for Demonstration circuit 2354A. Burst Mode operation and user can synchronize it with Design files for this circuit board are available at external clock also. Fixed-frequency mode of operation DEMO MANUAL DC2354A QUICK START PROCEDURE Demonstration circuit 2354A is easy to set up to evaluate 3. Set JP2 (RUN) into OFF and then jumper JP3 (V ) OUT the performance of the LTC7149. For proper measurement into 3.3V position. equipment configuration, set up the circuit according to 4. Turn on V of the circuit by inserting the shunt in OUT2 the diagram in Figure 1. Before proceeding to test, insert header JP2 (RUN) into the ON position. The output shunt into JP2 (RUN) into OFF position, which connects voltage should be regulating. Measure V , it should OUT the RUN pin to ground (GND), and thus, shutdown the measure 3.3V 2% (do not apply more than the output. Set jumper JP1 (MODE) into FCC (Forced Coun- maximum voltage of 55V to the board or the part may ties Conduction Mode) position. Set jumper JP3 (V ) OUT be damaged). Vary the current load, which should not into 5.0V position. exceed 4A. Vary the input voltage from 3.5V to 55V, NOTE: When measuring the input or output voltage the V , it should measure 3.3V 2%. OUT ripple, care must be taken to avoid a long ground lead 5. Set output current to zero and move jumper JP1 (MODE) on the oscilloscope probe. Measure the input or output into BURST position and measure V , which should OUT voltage ripple by touching the probe tip directly across be 3.3V 2%. the V or V and GND terminals. See Figure 2 for IN OUT 6. Set output current to zero and move jumper JP1 (MODE) proper scope probe technique. into BURST position and measure V , which should OUT 1. With the DC2354A set up according to the proper be 5V 2%.. measurement and equipment in Figure 1, apply 16V DC2354A supports synchronization to external clock at V . Measure V it should read 0V. If desired, IN OUT referenced to input GND use EXT SYNC terminal for syn- one can measure the shutdown supply current at this chronization. PGOOD signal also referenced to input GND, point. The supply current will be approximately 14A, to activate PGOOD functionality connect external voltage or less, in shutdown. source to terminals VLOGIC and GND. DC2354A supports 2. Turn on V of the circuit by inserting the shunt in OUT also EXTV function, however, EXTV is referenced to CC CC header JP2 (RUN) into the ON position. The output V . Remove R5 and install optional R33 10 resistor OUT voltage should be regulating. Measure V and it OUT if external EXTV voltage source is used. CC should measure 5.0V 2%. Vary the current load, Note: Do not apply more than the maximum voltage of which should not exceed 4A. Vary the input voltage 55V to the board or the part may be damaged. from 3.5V to 55V, the V , it should measure 5.0V OUT 2%. Maximum load current is function of input voltage and should be changed accordance to derating graphs on Figure 3. dc2354af 2