ADP2381-EVALZ

Evaluation Board User Guide UG-504 One Technology Way • P.O. Box 9106 • Norwood, MA 02062-9106, U.S.A. • Tel: 781.329.4700 • Fax: 781.461.3113 • www.analog.com Evaluation Board for the ADP2380 and ADP2381, 20 V, 4 A/6 A Synchronous Step-Down Regulators with Low-Side Driver FEATURES GENERAL DESCRIPTION Input voltage: 4.5 V to 20 V ±1% output voltage accuracy Integrated 44 mΩ high-side MOSFET Continuous output current 4 A for the ADP2380 6 A for the ADP2381 Programmable switching frequency: 250 kHz to 1.4 MHz Synchronizes to external clock: 250 kHz to 1.4 MHz 180° out-of-phase synchronization Programmable UVLO Power-good output External compensation Internal soft start with external adjustable option Startup into a precharged output The ADP2380/ADP2381 evaluation board is a complete, 4 A/6 A, 20 V, step-down regulator solution that allows users to evaluate the performance of the ADP2380 and the ADP2381 with a nearly ideal printed circuit board (PCB) layout. The switching frequency can be programmed between 250 kHz and 1.4 MHz, or it can be synchronized to an external clock with a 180° phase shift, which provides the possibility for a stackable, multiphase power solution. The output of the ADP2380/ADP2381 evaluation board is preset to 3.3 V, and the switching frequency is set to 500 kHz. Different output voltage settings can be achieved by changing the appropriate passive components. The ambient temperature operating range is −40°C to +85°C. Full details about the ADP2380 and ADP2381 regulators are provided in the ADP2380 and ADP2381 data sheets, which are available from Analog Devices, Inc. The data sheets should be consulted in conjunction with this user guide. 11203-001 DEMO BOARD Figure 1. PLEASE SEE THE LAST PAGE FOR AN IMPORTANT WARNING AND LEGAL TERMS AND CONDITIONS. Rev. 0 | Page 1 of 12 UG-504 Evaluation Board User Guide TABLE OF CONTENTS Features .............................................................................................. 1  Evaluation Board Schematics and Artwork ...................................5  General Description ......................................................................... 1  ADP2380 Schematic ......................................................................5  Demo Board ...................................................................................... 1  ADP2381 Schematic ......................................................................6  Revision History ............................................................................... 2  PCB Layout ....................................................................................7  Using the Evaluation Board............................................................. 3  Ordering Information .......................................................................8  Powering Up .................................................................................. 3  Bill of Materials ..............................................................................8  Measuring Evaluation Board Performance .................................. 3  Modifying the Board .................................................................... 4  REVISION HISTORY 12/12—Revision 0: Initial Version Rev. 0 | Page 2 of 12 Evaluation Board User Guide UG-504 USING THE EVALUATION BOARD POWERING UP MEASURING EVALUATION BOARD PERFORMANCE The ADP2380/ADP2381 evaluation board is supplied fully assembled and tested. Before applying power to the evaluation board, follow the procedures in this section. Measuring the Switching Waveform To observe the switching waveform with an oscilloscope, place the oscilloscope probe tip at Test Point J4 (SW) with the probe ground at J16 (GND). Set the scope to dc with the appropriate voltage and time divisions. The switching waveform limits should alternate approximately between 0 V and the input voltage. Jumper J12 (EN/SS) Use one of the following methods to enable or disable the regulator: • • Measuring Load Regulation To enable the regulator, leave Jumper J12 open. To disable the regulator, short Jumper J12. Load regulation can be tested by observing the change in the output voltage with increasing output load current. To minimize the voltage drop, use short, low resistance wires. Input Power Source If the input power source includes a current meter, use that meter to monitor the input current. Connect the positive terminal of the power source to J5 (VIN) of the evaluation board, and the negative terminal of the power source to J14 (GND) of the evaluation board. Measuring Line Regulation If the power source does not include a current meter, connect a current meter in series with the input source voltage. Connect the positive lead (+) of the power source to the positive (+) ammeter terminal, the negative lead (−) of the power source to J14 (GND), and the negative lead (−) of the ammeter to J5 (VIN). Generate a step input voltage change and observe the behavior of the output voltage using an oscilloscope. Output Load Before connecting the load, ensure that the board is turned off. Connect an electronic load or resistor to set the load current. Connect the positive terminal of the load to J6 (VOUT) of the evaluation board and connect the negative terminal of the load to J13 (GND). Vary the input voltage and examine the change in the output voltage with a fixed output current. Line Transient Response Load Transient Response Generate a load current transient at the output and observe the output voltage response using an oscilloscope. Attach the current probe to the wire between the output and the load to capture the current transient waveform. Measuring Efficiency The efficiency, η, is measured by comparing the input power with the output power. η= Input and Output Voltmeter Measure the input and output voltages using voltmeters. Ensure that the voltmeters are connected to the appropriate terminals of the evaluation board and not to the load or power source. If the voltmeters are not connected directly to the evaluation board, the measured voltages are incorrect, due to the voltage drop across the leads and/or connections between the evaluation board, the power source, and/or the load. To measure the input voltage, connect the positive terminal of the voltmeter to J7 (VIN_SENSE) and the negative terminal to J11 (GND_SENSE). Likewise, to measure the output voltage, connect the positive terminal of the voltmeter to J8 (VOUT_SENSE) and the negative terminal to J10 (GND_SENSE). Turning On the Evaluation Board Measure the input and output voltages as close as possible to the input and output capacitors to reduce the effect of voltage drop. Measuring Inductor Current The inductor current can be measured by removing one end of the inductor from its pad and connecting a current loop in series. A current probe can be connected onto this wire. Measuring Output Voltage Ripple To observe the output voltage ripple, place the oscilloscope probe across the output capacitor with the probe ground lead connected to the negative (−) capacitor terminal and the probe tip placed at the positive (+) capacitor terminal. Set the oscilloscope to ac, 10 mV/division, 2 µs/division time base, and 20 MHz bandwidth. When the power source and load are connected to the evaluation board, it can be powered for operation. Perform the following steps to turn on the board: 1. 2. 3. VOUT × I OUT V IN × I IN Ensure that the power source voltage is >4.5 V and