DEMO MANUAL DC1780A-A LTM4620EV: High Efficiency, PolyPhase 50A Step-Down Power Module Regulator DESCRIPTION + Demonstration circuit 1780A-A features PolyPhase voltage is tightly regulated between V and V OUT OUT design using the LTM 4620EV, the high efficiency, high through remote output voltage sensing which improves density, dual 13A, switch mode step-down power module output voltage regulation at heavy loads. These features regulator. The input voltage is from 4.5V to 16V. The and the availability of the LTM4620EV in a compact 15mm output voltage is jumper selectable from 1.0V to 2.5V. 15mm 4.41mm LGA package make it ideal for use in DC1780A-A can deliver nominal 50A output current with 2 many high-density point-of-load regulation applications. LTM4620s in parallel. As explained in the data sheet, output The LTM4620 data sheet must be read in conjunction with current derating is necessary for certain V , V , and this demo manual prior to working on or modifying the IN OUT thermal conditions. The LTM4620 on DC1780A-A always demo circuit DC1780A-A. operate in continuous conduction mode. The switching Design files for this circuit board are available at frequency can be programmed through a resistor or can DEMO MANUAL DC1780A-A PERFORMANCE SUMMARY Specifications are at T = 25C A PARAMETER CONDITIONS/NOTES VALUE Input Voltage Range 4.5V to 16V Output Voltage V V = 4.5V to 16V, I = 0A to 50A, JP4: 1.0V 1.0V 1.5% (0.985V to 1.015V) OUT IN OUT Maximum Continuous Output Current Derating is necessary for certain V , V and thermal 50A IN OUT conditions, see data sheet for detail. Default Operating Frequency 500kHz Resistor Programmable Frequency Range 400kHz to 780kHz External Clock Sync. Frequency Range 400kHz to 780kHz Efficiency V = 12V, V = 1.0V, I = 50A, f = 500kHz 82.4% See Figure 4 IN OUT OUT SW Load Transient V = 12V, V = 1.0V, I = 25A to 50A <138mV, See Figure 5 IN OUT SETP Output Voltage Ripple V = 12V, V = 1.0V, I = 50A <10mV, See Figure 6 IN OUT OUT QUICK START PROCEDURE Table 1. LTM4620 Demo Cards for up to 100A Point-of-Load Regulation MAXIMUM NUMBER OF OUTPUT NUMBER OF LTM4620 MODULE OUTPUT CURRENT VOLTAGES REGULATORS ON THE BOARD DEMO CARD NUMBER 13A, 13A 2 1 DC1498A 50A 1 2 DC1780A-A 75A 1 3 DC1780A-B 100A 1 4 DC1780A-C Demonstration circuit DC1780A-A is easy to set up to 3. Turn on the power supply at the input. Place JP2 to + evaluate the performance of PolyPhase operation of the ON position. The output voltage between V and OUT LTM4620EV. Due to the high input/output current, select V should be 1.0V 1.5% (0.985V to 1.015V). OUT a proper input supply/load/cable which can sustain the 4. Once the proper output voltage is established, adjust the full load operation. Please refer to Figure 2 for proper load within the operating range and observe the output measurement setup and follow the procedure below: voltage regulation, output voltage ripple, efficiency 1. Place jumpers in the following positions for a typical and other parameters. Output voltage ripple should 1.0V application: be measured at J7 with BNC cables. 50 termination OUT should be set on the oscilloscope or BNC cables. JP1 JP2 JP4-JP8 5. (Optional) For optional load transient test, apply an CLK RUN V SELECT OUT adjustable pulse signal between IOSTEP CLK and GND INT CLK OFF ON JP4/1.0V test point. The pulse amplitude (3V to 3.5V) sets the load step current amplitude. The output transient current can 2. With power off, connect the input power supply, load be monitored at the BNC connector J8 (5mV/A). The and meters as shown in Figure 2. Preset the load to 0A pulse signal should be very small duty cycle (< 10%) and V supply to 12V. IN to limit the thermal stress on the transient load circuit. dc1780aafa 2