DEMO MANUAL DC1663A LTM4628EV High Efficiency, Dual 8A Step-Down Power Module Regulator DESCRIPTION Demonstration circuit DC1663A features the LTM 4628EV, board allows the user to program how its output ramps the high efficiency, high density, dual 8A output, switch up and down through the TRACK/SS pin. The output can mode step-down power module. The input voltage is be set up to either coincidentally or ratio metrically track from 4.5V to 26.5V. The output voltage is programmable with another supplys output. Remote output voltage sens- from 0.6V to 5.5V. Output current derating is necessary ing is available for improved output voltage regulation at for certain V , V , and thermal conditions. The board the load point. These features and the availability of the IN OUT operates in continuous conduction mode in heavy load LTM4628EV in a compact 15mm 15mm 4.32mm LGA conditions. For high efficiency at low load currents, the package make it ideal for use in many high density point MODE jumper (JP1) selects pulse-skipping mode for of load regulation applications. The LTM4628 datasheet noise sensitive applications or Burst Mode operation must be read in conjunction with this demo manual for in less noise sensitive applications. The DC1663A sets working on or modifying the demo circuit DC1663A. the LTM4628EV default switching frequency to 400kHz Design files for this circuit board are available at however the frequency is resistor programmable from DEMO MANUAL DC1663A PERFORMANCE SUMMARY (T = 25C) A PARAMETER CONDITION VALUE Input Voltage Range 4.5V to 26.5V Output Voltage V V = 4.5 to 26.5V, I = 0A to 8A, JP1: CCM 1.5V 1.5% (1.4775V to 1.5225V) OUT1 IN OUT1 Output Voltage V V = 4.5 to 26.5V, I = 0A to 8A, JP1: CCM 1.2V 1.5% (1.182V to 1.218V) OUT2 IN OUT2 Per Channel Maximum Continuous Output Current Derating is Necessary for Certain V , V and 8A IN OUT Thermal Conditions, See Datasheet for Details. Default Operating Frequency 400kHz External Clock Synchronous Frequency Range 400kHz to 780kHz Efficiency of Channel 1 V = 5V, V = 1.5V, I = 8A, f = 400 kHz 87.7% See Figure 2 IN OUT1 OUT1 SW Efficiency of Channel 2 V = 5V, V = 1.2V, I = 8A, f = 400 kHz 85.5% See Figure 3 IN OUT2 OUT2 SW Load Transient of Channel 1 V = 12V, V = 1.5V, I = 0A to 4A See Figure 4 IN OUT1 SETP Load Transient of Channel 2 V = 12V, V = 1.2V, I = 0A to 4A See Figure 5 IN OUT2 SETP QUICK START PROCEDURE Demonstration circuit DC1663A is easy to set up to evalu- 5. (Optional) For optional load transient test, apply an ate the performance of the LTM4628EV. Please refer to adjustable pulse signal between IOSTEP CLK and GND Figure 1 for proper measurement equipment setup and pins. Pulse amplitude (3V to 3.5V) sets the load step the following the procedure: current amplitude. The pulse signal should have very small duty cycle (< 10%) to limit the thermal stress on 1. Place jumpers in the following positions for a typical the transient load circuit. The output transient current application: can be monitored at the SMA connector J3 (15mV/A). JP1 JP2 JP3 JP4 JP5 JP6 Apply the jumper resistors R34 or R35 (on the back- MODE RUN1 RUN2 TRACK1 TRACK2 CLKOUT side of boards) to apply load transient on channel 1 or SEL. SEL. PHASE channel 2 correspondingly. CCM ON ON SOFT- SOFT- 60 START START 6. (Optional) LTM4628 can be synchronized to an external clock signal. Remove the jumper on JP1 and apply a clock signal (0V to 5V, square wave) on the CLKIN test point. 2. With power off, connect the input power supply, load and meters as shown in Figure 1. Preset the load to 0A 7. (Optional) The outputs of LTM4628 can track another and V supply to 12V. supply. The jumpers JP4 and JP5 allow choosing soft- IN start or output tracking. If tracking external voltage 3. Turn on the power supply at the input. The output volt- is selected, the corresponding test points, TRACK1 age in channel 1 should be 1.5V 1.5% and the output and TRACK2, need to be connected to a valid voltage voltage in channel 2 should be 1.2V 1.5%. signal. 4. Once the proper output voltage is established, adjust the 8. (Optional) LTM4628 can be configured for a 2-phase load within the operating range and observe the output single output at up to 16A on DC1663A. Refer to the voltage regulation, output voltage ripple, efficiency and schematic for corresponding jumper resistor setup for other parameters. Output ripple should be measured at dual phase single output applications. J1 and J2 with SMA cables. 50 termination should be set on the oscilloscope or SMA cables. dc1663af 2