DEMO MANUAL DC2616A-B LTM4645 High Efficiency, PolyPhase 75A Step-Down Power Module Regulator DESCRIPTION Demonstration circuit 2616A-B features a polyphase the MODE PLLIN jumper selects pulse-skipping mode design using the LTM 4645EY, a 25A high efficiency, for noise sensitive applications or burst mode operation switch mode step-down power Module regulator. The in less noise sensitive applications. The MODE PLLIN input voltage range is from 6V to 15V. To use DC2616A-B pin also allows the LTM4645 to synchronize to an exter- for input voltage range from 4.7V to 6V, connect INTV nal clock signal. The phase shift between two adjacent CC to SV (change R22, R42, R55 from OPT to 0), DRV phases is 120 degrees. DC2616A-B has the option of IN CC to V (change R21, R38, R52 from 0 to OPT, R2, R39, choosing both internal and external compensation circuit IN R53 from OPT to 0). The output voltage range is 0.6V for LTM4645. The LTM4645 data sheet must be read in to 1.8V. The DC2616A-B can deliver a nominal 75A out- conjunction with this demo manual prior to working on put current with three LTM4645 modules in parallel. As or modifying demo circuit DC2616A-B. explained in the data sheet, output current derating is nec- Design files for this circuit board are available. essary for certain V , V , and thermal conditions. The IN OUT All registered trademarks and trademarks are the property of their respective owners. board operates in continuous conduction mode in heavy load conditions. For high efficiency at low load currents, BOARD PHOTO Rev. 0 1DEMO MANUAL DC2616A-B PERFORMANCE SUMMARY Specifications are at T = 25C A PARAMETER CONDITIONS VALUE Input Voltage Range 6V to 15V Output Voltages 1.0V 1.2% Maximum Continuous Output Current De-rating is Necessary for Certain Operating 75ADC Conditions. See Data Sheet for Details. Operating Frequency 600kHz Efficiency V = 12V, V = 1.0V, I = 75A 84.5% Figure 2 IN OUT OUT Load Transient V = 12V, V =1.0V, I = 0A to 18.75A 53.8mV Figure 3 IN OUT STEP QUICK START PROCEDURE Demonstration circuit DC2616A-B is an easy way to 4. Vary the input voltage from 6V to 15V and adjust the evaluate the performance of polyphase operation of the load current from 0A to 75A. Observe the output volt- LTM4645EY. Due to the high input/output current, the age regulation, ripple voltage, efficiency, and other user should select the proper input supply/load/cable parameters. which can sustain the full load operation. Please refer to 5. (Optional) For optional load transient test, apply an Figure 1 for proper measurement equipment setup and adjustable pulse signal between IOSTEP CLK and GND follow the procedure below: test points. The pulse amplitude sets the load step cur- 1. Place jumpers in the following positions for a typical rent amplitude. Keep the pulse width short (<1ms) and application: pulse duty cycle low (<5%) to limit the thermal stress on the load transient circuit. MODE RUN 6. (Optional) LTM4645 can be synchronized to an external CCM ON clock signal. Apply a clock signal (0V to 5V, square 2. With power off, connect the input power supply, load wave) on the MODE PLLIN test point. and meters as shown in Figure 1. Preset the load to 0A 7. (Optional) The outputs of LTM4645 can track another and V supply to 12V. IN supply. The output voltage tracks the voltage on TRACK 3. Turn on the power supply at the input. The output volt- when a valid signal is applied on the test point. age should be 1.0V 1.2% (0.988V to 1.012V). Rev. 0 2