DEMO MANUAL DC1856A-B LTM4649EY 10A Step-Down Module Regulator DESCRIPTION Demonstration circuit 1856A-B features the LTM 4649EY voltage tracking is available through the TRACK/SS pin for Module regulator, a high performance, high efficiency supply rail sequencing. External clock synchronization is step-down regulator. The LTM4649EY has an operating also available through the CLKIN pin. The LTM4649 data input voltage range of 4.5V to 16V and is able to provide sheet must be read in conjunction with this demo manual an output current of up to 10A. The output voltage is pro- prior to working on or modifying demo circuit 1856A-B. grammable from 0.6V to 5V and can be remotely sensed Design files for this circuit board are available at with the internal differential remote sensing amplifier. The DEMO MANUAL DC1856A-B QUICK START PROCEDURE the load regulation, efficiency, and other parameters. Demonstration circuit 1856A-B is an easy way to evaluate Output voltage ripple should be measured at J6 with a the performance of the LTM4649EY. Please refer to Figure 1 BNC cable and oscilloscope. for test setup connections and follow the procedure below. 6. To observe increased light load efficiency place the 1. With power off, place the jumpers in the following Mode pin jumper (JP9) in the Burst Mode position. To positions for a typical 1.8V application: OUT observe increased light load efficiency with a reduced JP8 JP7 JP9 JP2 output ripple as compared to Burst Mode operation place TRACK/SS RUN MODE V Select OUT the Mode pin jumper in the pulse-skipping position. SS ON CCM 1.8V 7. For optional load transient testing apply an adjustable 2. Before connecting input supply, load and meters, preset positive pulse signal between IOSTEP CLK and GND the input voltage supply to be between 4.5V to 16V. pins. The pulse amplitude sets the load step current Preset the load current to 0A. amplitude. The pulse width should be short (<1ms) and pulse duty cycle should be low (<15%) to limit the 3. With power off, connect the load, input voltage supply thermal stress on the load transient circuit. The load and meters as shown in Figure 1. step current can be monitored with a BNC connected 4. Turn on input power supply. The output voltage meter to J5 (10mV/A). should display the selected output voltage 2%. Note: To evaluate PGOOD pin operation for the LTM4649, 5. Once the proper output voltage is established, adjust insert a 100k resistor between PGOOD and INTVCC. Do the load current within the 0A to 10A range and observe not stuff R15. + LOAD 0A TO 10A V IN Figure 1. Test Setup of DC1856A-B dc1856a-bf 2 + A + + V + A V +