DEMO MANUAL DC2389A LTM8073 60V, 3A Silent Switcher Module Regulator Dtpircse Demonstration circuit 2389A is a 60V, 3A step-down appropriate voltage divider if V is 2.9V or higher. See OUT Module regulator featuring the LTM 8073. The demo Quick Start Procedure section for more details. board is designed for 5V output from a 7V to 60V input. Figure 1 shows the efficiency of the circuit under differ- The wide input range allows a variety of input sources, ent input voltages in Burst Mode operation. The rated such as automotive batteries and industrial supplies. The maximum load current is 3A, while derating is necessary user adjustable features of the LTM8073 such as output for certain input voltage and thermal conditions. Figure 2 voltage, switching frequency, soft-start and power good shows the LTM8073 thermal performance on DC2389A can be changed on DC2389A simply by modifying the demo board. appropriate resistors and/or capacitors. Two or more The demo board has an EMI filter installed. An inductor LTM8073s can be paralleled to share load current equally. L1, which is shorted on the board by default, can be added The LTM8073 can be programmed to different operation in the EMI filter to further reduce the conducted emission. modes. The SYNC pin on the demo board is grounded The LTM8073 data sheet gives a complete description of by default for low ripple Burst Mode operation. Moving the part, operation and application information. The data JP1 to PULSE SKIPPING position can change the opera- sheet must be read in conjunction with this demo manual tion mode to pulse-skipping operation. To synchronize for demo circuit 2389A. to an external clock, move JP1 to SYNC and apply the external clock to the SYNC turret. Once JP1 is on SPREAD Design files for this circuit board are available at SPECTRUM position, an external DC bias can be applied DEMO MANUAL DC2389A p ecnrofre s yr Specifications are at T =25C A SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS V Input Voltage Range 7 60 V IN V Output Voltage 4.85 5 5.15 V OUT I Maximum Output Current 3 A OUT f Switching Frequency 1.2 MHz SW EFF Efficiency at DC V =12V, I =1A 93.9 % IN OUT 100 70 60 90 50 80 40 30 70 20 60 I = 2A OUT 10 12V INPUT I = 2.5A OUT 24V INPUT I = 3A OUT 50 0 0 0.1 1 10 0 10 20 30 40 50 60 70 LOAD CURRENT (A) V (V) IN DC2389 F01 DC2389 F02 Figure 2. LTM8073 Demo Circuit DC2389A Figure 1. LTM8073 Demo Circuit Case Temperature Rise vs Input Voltage DC2389A Efficiency vs Load Current 0 FIXED FREQUENCY SPREAD SPECTRUM MODE 20 40 V OUT 10mV/DIV 60 80 100 DC2389 F04 500ns/DIV 120 0 2 4 6 8 10 Figure 4. DC2389A Output Ripple, FREQUENCY (MHz) V =12V, V =5V, I =3A DC2389 F03 IN OUT OUT Figure 3. DC2389A Output Noise Spectrum, V =12V, V =5V, I =3A IN OUT OUT dc2389af 2 INTENSITY (dBm) EFFICIENCY (%) CASE TEMPERATURE RISE (C) umma ma