DC2005A Analog Devices

DEMO MANUAL DC2005A LTC3624EDD High Efficiency Synchronous Step-Down Regulator with Ultralow Quiescent Current DESCRIPTION Demonstration circuit DC2005A is a synchronous step- The DC2005A uses very low profile surface mount com- down regulator using an LTC 3624 monolithic buck ponents and all ceramic output capacitors. The compact regulator. The DC2005A operates from an input voltage 8-lead DFN (3mm 3mm) package makes the LTC3624 an range of 2.7V to 17V and provides an adjustable output excellent choice for battery-powered equipment, general voltage range from 1.2V to 5V (V < V ) at 2A of output purpose step-down power supply, and emergency radio OUT IN current. A user-selectable mode input is provided to allow applications. the user to trade off ripple noise for light load efficiency. It is recommended to read the data sheet and demo manual Burst Mode operation provides the highest efficiency at of the LTC3624 prior using or making any changes to light load, while pulse-skipping mode provides the lowest DC2005A. voltage ripple. The MODE pin can also be used to sync the Design files for this circuit board are available at switching frequency to an external clock. DEMO MANUAL DC2005A QUICK START PROCEDURE Demonstration circuit DC2005A is easy to set up to evaluate 7. To select other output voltages, use the on board user the performance of the LTC3624. Please refer to Figure1 selectable output voltage jumpers. Shutting down for proper measurement equipment setup and follow the LTC3624 by placing RUN pin jumper (JP1) to the OFF procedure below: position or turn off the input power supply. Refer to the following table (Table 2) for the output voltage selection 1. Place jumpers in the following positions for a typical and repeat steps 2 to 6: 5V output application: Table 2. Output Voltage Jumper Selection Table 1. Typical 5V Output Voltage Jumper Selection JP3 JP4 JP5 JP6 JP7 JP8 JP1 JP2 JP7 1.2V 1.8V 2.5V 3.3V 5V *User Select RUN MODE/SYNC VOUT * Note: If JP8 is selected, R6 needs to be calculated and inserted to ON BM 5.0V obtain the desired output voltage. 2. With power off, connect the input power supply at VIN Note 1: To measure the input/output voltage ripple prop- (E1) and GND (E2). erly, do not use the long ground lead on the oscilloscope probe. See Figure 2 for the proper scope probe technique. 3. Connect the load between VOUT (E8) and GND (E9). Short, stiff leads need to be soldered to the (+) and () Preset the load to 0A. terminals of an output capacitor. The probes ground ring 4. Connect the DMMs to the input and output to monitor needs to touch the () lead and the probe tip needs to the input voltage and output voltage. touch the (+) lead. 5. Turn on the power supply at the input. The RUN pin Note 2: The DC2005A can also be used to evalu- jumper should be at ON position. Measure and make ate LTC3624-2 (2.25MHz) by simply changing U1 to sure the input supply voltage is 12V. The output voltage LTC3624-2 and L1 to 1.5H (Coilcraft XAL4020-152ME). should be 5V 2%. 6. Once the input and output voltages are properly es- tablished adjust the loads within the operating range (0A to 2A max) and observe the output voltage regula- tion, output ripple voltage, switch node waveform and other parameters. Refer to Figure 2 for proper input/ output voltage ripple measurement. dc2005af 2