DEMO MANUAL DC2378A-B LTM4650-1 High Efficiency, Single 50A or Dual 25A Step-Down Power Module Regulator Description Demonstration circuit DC2378A-B features the how its output ramps up and down through the TRACK/ LTM 4650EY-1, the high efficiency, high density, dual SS pin. The output can be set up to either coincidentally or 25A, single 50A, switch mode step-down power module ratiometrically track with another supplys output. Remote regulator. The input voltage is from 4.5V to 15V. The output output voltage sensing is available for improved output voltage is programmable from 0.6V to 1.8V. DC2378A-B voltage regulation at the load point. These features and can deliver 25A maximum current from each channel. As the availability of the LTM4650EY-1 in a compact 15mm explained in the data sheet, output current derating is nec- 15mm 5.01mm BGA package make it ideal for use in essary for certain V , V , and thermal conditions. The many high density point-of-load regulation applications. IN OUT board operates in continuous conduction mode in heavy The LTM4650-1 data sheet must be read in conjunction load conditions. For high efficiency at low load currents, the with this demo manual for working on or modifying the MODE jumper (JP1) selects pulse-skipping mode for noise demo circuit DC2378A-B. sensitive applications or Burst Mode operation in less Design files for this circuit board are available at noise sensitive applications. Two outputs can be connected DEMO MANUAL DC2378A-B p s Specifications are at T = 25C A PARAMETER CONDITIONS MIN TYP MAX UNITS Input Voltage Range 4.5 15 V Output Voltage V V = 4.5V ~ 15V, I = 0A ~ 25A, JP1: CCM 1.5 1.5% V OUT1 IN OUT1 Output Voltage V V = 4.5V ~ 15V, I = 0A ~ 25A, JP1: CCM 1 1.5% V OUT2 IN OUT2 Per-Channel Maximum Continuous Output Derating Is Necessary for Certain V , V and 25 A IN OUT Current Thermal Conditions, See Data Sheet for Detail. (Per-Channel) Default Operating Frequency 500 kHz Resistor Programmable Frequency Range 250 780 kHz External Clock Sync. Frequency Range 400 780 kHz Efficiency of Channel 1 V = 12V, V = 1.5V, I = 25A, f = 500kHz 88.8 % IN OUT1 OUT1 SW See Figure 4 Efficiency of Channel 2 V = 12V, V = 1V, I = 25A, f = 500kHz 86.5 % IN OUT2 OUT2 SW See Figure 5 Load Transient of Channel 1 V = 12V, V = 1.5V, I = 12.5A ~ 18.75A See Figure 6 IN OUT1 STEP Load Transient of Channel 2 V = 12V, V = 1V, I = 12.5A ~ 18.75A See Figure 7 IN OUT2 STEP Quick s p D Demonstration circuit DC2378A-B is easy to set up to 5. (Optional) For optional load transient test, apply an evaluate the performance of the LTM4650EY-1. Please adjustable pulse signal between IOSTEP CLK and GND refer to Figure 2 for proper measurement setup and follow test point. Pulse amplitude (3V ~ 3.5V) sets the load the procedure below: step current amplitude. The output transient current can be monitored at the BNC connector J3 (10mV/A). 1. Place jumpers in the following positions for a typical The pulse signal should have very small duty cycle (< application: 1%) to limit the thermal stress on the transient load JP1 JP2 JP3 JP4 JP5 circuit. Switch the jumper resistors R34 or R35 (on the MODE RUN1 RUN2 TRACK1 TRACK2 backside of boards) to apply load transient on channel SEL. SEL. 1 or channel 2 correspondingly. CCM ON ON SOFT- SOFT- START START 6. (Optional) LTM4650-1 can be synchronized to an external clock signal. Place the JP1 jumper on EXT CLK 2. With power off, connect the input power supply, load and apply a clock signal (0V ~ 5V, square wave) on the and meters as shown in Figure 2. Preset the load to 0A CLKIN test point. and V supply to 12V. IN 7. (Optional) The outputs of LTM4650-1 can track another 3. Turn on the power supply at the input. The output supply. The jumpers JP4 and JP5 allow choosing soft- voltage in channel 1 should be 1.5V 1.5% (1.4775V start or output tracking. If tracking external voltage is ~ 1.5225V) and the output voltage in channel 2 should selected, the corresponding test points, TRACK1 and be 1V 1.5% (0.985V ~ 1.015V). TRACK2, need to be connected to a valid voltage signal. 4. Once the proper output voltage is established, adjust the 8. (Optional) LTM4650-1 can be configured for a 2-phase load within the operating range and observe the output single output at up to 50A on DC2378A-B. Install 0 voltage regulation, output voltage ripple, efficiency and resistors on R14, R17, R28, R39, R43, R44, R45 and other parameters. Output ripple should be measured remove R7, R19. Output voltage is set by R25 based at J1 and J2 with BNC cables. 50 termination should on equation V = 0.6V(1 + 60.4k/R25). OUT be set on the oscilloscope or BNC cables. dc2378abfa 2 ure roce tart ummary erformance