DEMO MANUAL DC1780A-B LTM4620EV: High Efficiency, PolyPhase 75A Step-Down Power Module Regulator DESCRIPTION + Demonstration circuit 1780A-B features PolyPhase The output voltage is tightly regulated between V OUT design using the LTM 4620EV, the high efficiency, high and V through remote output voltage sensing which OUT density, dual 13A, switch mode step-down power module improves output voltage regulation at heavy loads. These regulator. The input voltage is from 4.5V to 16V. The features and the availability of the LTM4620EV in a compact output voltage is jumper selectable from 1.0V to 2.5V. 15mm 15mm 4.41mm LGA package make it ideal for DC1780A-B can deliver nominal 75A output current with use in many high density point-of-load regulation applica- 3 LTM4620s in parallel. As explained in the data sheet, tions. The LTM4620 data sheet must be read in conjunction output current derating is necessary for certain V , V , with this demo manual prior to working on or modifying IN OUT and thermal conditions. The LTM4620 on DC1780A-B the demo circuit DC1780A-B. always operates in continuous conduction mode. The Design files for this circuit board are available at switching frequency can be programmed through a resistor DEMO MANUAL DC1780A-B 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 75A, 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 75A 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 = 75A, f = 500kHz 80.6% See Figure 4 IN OUT OUT SW Load Transient V = 12V, V = 1.0V, I = 37.5A to 75A <163mV, See Figure 5 IN OUT SETP Output Voltage Ripple V = 12V, V = 1.0V, I = 75A, f = 500kHz <10mV, See Figure 6 IN OUT OUT SW 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 QUICK START PROCEDURE Demonstration circuit DC1780A-B is easy to set up to 4. Once the proper output voltage is established, adjust the evaluate the performance of PolyPhase operation of the load within the operating range and observe the output LTM4620EV. Due to the high input/output current, select voltage regulation, output voltage ripple, efficiency a proper input supply/load/cable which can sustain the and other parameters. Output voltage ripple should full load operation. Please refer to Figure 2 for proper be measured at J7 with BNC cables. 50 termination measurement setup and follow the procedure below: should be set on the oscilloscope or BNC cables. 1. Place jumpers in the following positions for a typical 5. (Optional) For optional load transient test, apply an 1.0V application: adjustable pulse signal between IOSTEP CLK and GND OUT test point. The pulse amplitude (3V to 3.5V) sets the load JP1 JP2 JP4-JP8 step current amplitude. The output transient current can CLK RUN V SELECT OUT be monitored at the BNC connector J8 (5mV/A). The INT CLK OFF ON JP4/1.0V pulse signal should be very small duty cycle (< 10%) to limit the thermal stress on the transient load circuit. 2. With power off, connect the input power supply, load 6. (Optional) LTM4620 can be synchronized to an external and meters as shown in Figure 2. Preset the load to 0A clock signal. Place the JP1 jumper on EXT CLK and and V supply to 12V. IN apply a clock signal (0V to 5V, square wave) on the EXT CLK test point. 3. Turn on the power supply at the input. Place JP2 to + ON position. The output voltage between V and OUT V should be 1.0V 1.5% (0.985V to 1.015V). OUT dc1780abfa 2