DEMO MANUAL DC1472A LTM4618EV: 6A Step-Down Power Module Regulator DESCRIPTION from pulse-skipping or Burst Mode operation for improved Demonstration circuit 1472 features the LTM 4618EV ef ciency at light load. DC1472 has a default switching Module regulator, a complete high ef ciency synchro- frequency of 500 kHz and is synchronizable to an external nous buck regulator. The DC1472 input range is from 4.5V clock from 250 kHz up to 750 kHz. These features and the to 26.5V and is capable of delivering up to 6A of output availability of the LTM4618EV in a compact 9mm 15mm current. However, current derating may be necessary under 4.32mm LGA package make the demonstration circuit certain V , V , frequency and thermal conditions. The IN OUT ideal for use in many high density point-of-load regula- output voltage for the board is jumper programmable from tion applications. The LTM4618 data sheet must be read 1.2V to 5V and can be set as low as 0.8V, the reference in conjunction with this demo manual for working on or voltage of the LTM4618EV. modifying the demo circuit 1472A. Layout is simple, requiring only a few bulk input and output Design les for this circuit board are available at capacitors externally. The TRACK/SS pin allows the user to DEMO MANUAL DC1472A PERFORMANCE SUMMARY PARAMETER CONDITIONS/NOTES VALUE Input Voltage Range 4.5V to 26.5V Jumper Selectable Output Voltage, V V = 4.5V 26.5V, I = 0A 6A 1.2V, 1.5V, 1.8V, 2.5V, 3.3V or 5V 2% OUT IN OUT Maximum Continuous Output Current Derating is Necessary for Certain Operating Conditions. 6A DC See Data Sheet for Details Default Operating Frequency R3 = 10k, R4 = 3.16k 500kHz External Clock Sync. Frequency Range 250kHz to 750kHz Ef ciency V = 12V, V = 2.5V, I = 6A 88.7% See Figure 2 IN OUT OUT QUICK START PROCEDURE Demonstration circuit 1472 is easy to set up to evaluate the 5. Measure the output voltage ripple at J5 with a BNC performance of the LTM4618EV. Please refer to Figure1 cable and oscilloscope. for proper measurement equipment setup and follow the 6. To set the output voltage to 5V, turn off the input supply procedure below. power, apply the following changes listed below and 1. With power off, connect the input power supply, load repeat steps 2 to 5: and meters as shown in Figure 1. Preset the load to 0A JP10 JP3 JP4 JP2 and V supply to be 0V. Place jumpers in the following IN V Select MODE RUN TRACK/SS OUT positions for a typical 1.5V application: OUT 5V CCM OFF SS JP6 JP3 JP4 JP2 7. Set the load current to 0A. Set the RUN pin jumper V Select MODE RUN TRACK/SS OUT (JP4) to the OFF position. Power off the input supply. 1.5V CCM OFF SS 8. For load transient tests, apply an adjustable positive pulse 2. Turn on the power at the input. Increase V to 12V IN signal between IOSTEP CLK and GND test points. The (Caution: Do not hot plug the input supply or apply pulse amplitude sets the load step current amplitude. more than the rated maximum voltage of 26.5V to the The pulse width should be short (<1ms) and pulse duty board or the part may be damaged). cycle should be low (<15%) to limit the thermal stress on the load transient circuit. The load step current can 3. Set the RUN pin jumper (JP4) to the on position. The be monitored with a BNC connected to J6 (10mV/A). output voltage should rise to 1.5V. The output voltage meter should read the selected output voltage 2%. 4. Vary the input voltage from 6V to 24V and adjust the load current from 0A to 6A. The output voltage meter should read the selected output voltage 2%. Set the input voltage to 12V and the load current to 6A. dc1472af 2